NO853360L - DEVICE FOR A DETERMINED VOLUME SPEED OF A LIQUID MEDIUM USING A SERVICE LEAD, AND ITS APPLICATION FOR REGULATION FORM OR MEASUREMENT OF HEAT QUANTITY - Google Patents

Abstract

1. A device for detecting the volumetric flow of a liquid medium through an adjusting element (1), which is designed as a straight-way valve (4) and comprises an inlet nozzle (2) and an outlet nozzle (3), of a control section with an elastically deformable sealing element (7, 12) such as a diaphragm which initiates an opening movement of a valve member (6) of the straight-way valve (4) against a spring force FF , and with a stroke sensor (10) for detecting the position of the valve member (6), from which the volumetric flow V can be derived by taking into consideration the pressure difference DELTA pv existing over the straight-way valve (4), in which a controlled control valve (19, 34) is connected via connecting conduits (16, 17, 18) to various chambers of the straight-way valve (4), characterised in that the control valve (19; 34) can be controlled by at least one controller (22; 35, 45) and connects a first chamber (13) of the straight-way valve (4) limited by the sealing element (7, 12) via the connecting conduits (16, 17, 18) in a first stable control state to a second chamber (14) and in a second stable control state to the third chamber (15), in that the second chamber (14) comprises the outlet nozzle (3) and the third chamber (15) the inlet nozzle (2), in that the effective surfaces of the sealing element (7, 12) and of the valve member (6) designed as a valve disc as well as the spring force FF are selected such that, in the control state, the pressure difference DELTA pv arising over the straight-way valve (4) opens this straight-way valve (4) by means of the valve disc and, in the first control state, the spring force FF closes this straight-way valve (4) by means of the valve disc, and in that the stroke sensor (10) is connected to a computer (21) for determining the pressure difference DELTA pv and/or the volumetric flow V on the basis of the starting signals of the controller (22, 35, 45) and of the stroke sensor (10).

Description

The invention relates to a device as stated in the introduction to patent claim 1 as well as its use in connection with a regulation of volume velocity and/or for measuring amounts of heat.

From DE-OS 32 44 668, it is known with a thermostatically operated passage valve to determine the volume velocity of the flow through it by determining the momentary degree of opening of the valve's valve disc and at the same time measuring the pressure drop across the passage valve. In this connection, it is unfortunate that, in addition to the passage valve, a measuring device is needed to determine the pressure drop.

The invention is based on the task to be done

it is possible to manage without any device for measuring the pressure drop and to determine the volume velocity in the through-valve solely from the stroke of the valve plates/ and furthermore to use the same through-valve as a servo element in a regulation section also for extended regulation tasks that require knowledge of the pressure drop across the servo element and /or the volume velocity of the flow through the servo element, as well as for measuring heat quantities.

The invention is characterized in patent claim 1.

In the following, examples of embodiments of the invention will be provided

be elucidated in more detail with reference to the drawing.

Fig. 1 schematically shows a device that has been made

in accordance with the invention and comprises a regulation section which has a two-point regulator and regulates a stroke length of the servo member in question.

Fig. 2 shows a group of diagrams.

Fig. 3 schematically shows another example of a device which is made in accordance with the invention, and which exhibits a three-point regulator. Fig. 4 shows a further group of diagrams and fig. 5 and 6 each show a functional diagram.

Before the device is described with reference to the figures, an explanation will be given below

all the sizes used in the description and formulas,

and that in the order in which they appear for the first time in the subsequent text.

Ap^ = pressure difference across valve 4

T ,T ,Tm = time during which the valve 4 closes

T,T^,T2= time during which the valve 4 opens

F-.,(s) = spring force (at stroke s)

?1= pressure in room 15

?2= pressure in room 14

s = stroke of the valve plate 6

s = average stroke of the valve disc 6

s = average opening speed of the valve plate 6

s^= mean closing speed of the valve plate 6

t = time

V = volume velocity of current through the servo element 1

f^, f 2 = functions

s max=stroke ^ at the end of the time period T

s^ = stroke at the end of the time interval T

my

F.. = force on the membrane 7, 12 according to AP

M ^ ^ m

Apm= pressure difference across the membrane 7, 12

Fy = valve force generated according to Ap^

AM., = effective membrane area

Off = effective valve area

Ap^= pressure difference across throttle 20

VR= volume velocity in throttling 20

I = length of choke 20

p = density of the flow medium v = kinematic viscosity of the flow medium d = diameter of choke 20

As = stroke change

v = flow rate

f^(s) = valve characteristic for servo link 1

d = diameter of the valve seat 5

v

Pp = pressure rise across the pump

= measured value of volume velocity

$y = flow temperature

= return temperature

A-& = temperature difference

Pj= released amount of heat

$j = measured value of room temperature

In fig. 1 and 3, 1 designates a servo element which is designed as a passage valve and has an inlet and an outlet connection 2 and 3, respectively, connected in the circuit for a hot water heating system not shown. The water, which is transported by a pump not shown, develops a pressure difference when it flows through the servo joint 1 over its valve 4. The valve 4 consists of

of a stationary valve seat 5 and a longitudinally movable valve disc 6. The valve disc 6 is connected via a rod mechanism 8 to a stretchable joint, in the design example a membrane 7 (fig. 1). Furthermore, on the rod mechanism 8 sits a sensor part 9 of a shock sensor 10 which works without contact. The rod mechanism 8 has, by means of spring elements not shown, radially fixed but longitudinally movable storage. In the absence of external forces, the valve plate 6 rests on the valve seat 5 due to the spring force, i.e. the valve

4 then is closed. In the example of fig. 1 becomes the closing force

produced by a coil spring 11 which is supported between the diaphragm 7 and the wall of the servo member 1 which shows the valve seat 6, and thus pulls the valve plate 6 towards the valve seat 5.

In the example of fig. 3 serves two steel membranes 12 and

12a at once to produce the closing force and to form radial bearing for the rod mechanism 8.

In the housing of the servo member 1, the membrane 7 delimits resp.

12 a first room 13 against another room 14 which has the outlet connection 3. Furthermore, the inlet connection 2 opens into a third room 15 which is separated from the second room 14 by means of the valve 4.

From each of the three rooms 13, 14, 15, a connection channel 16, 17, 18 leads to a control valve 19. In the design example in fig. 1, the control valve 2 can assume two stable control states a and b. In the first control state a, the control valve connects the first room 13 via the connection channels 16 and 17 with the second room 14 for a period of time T, while the connection channel 18 is closed in this state.

The connection channel 16 is designed with a bottleneck

20 whose cross-section is reduced in relation to the cross-section of the connection channels 16, 17, 18.

In its second control state b, the control valve connects

19 during a period of time T via the same connection channel 16 including the bottleneck 20 first room 13 with third room 15 via the connection channel 18, while the connection channel 17 is closed.

The effective areas of the diaphragm 7 and the valve plate

6 is together with the spring force F„ r - in fig. 1 the force of the screw spring 11, in fig. 3 the force of the steel membranes 12 and 12a

- chosen so that the valve 4 in the second control condition b of the control valve 19 opens due to the formed pressure difference Ap^ across the valve 4 and in the first control condition a closes. IN

in this connection, the closing function is ensured even if the pump is stationary, e.g. in the event of a power failure, there is absolutely no pressure difference across valve 4.

In another control condition b, pressure P^ prevails

in room 157 via the connection channels 18 and 16 with the choke 20 also up into room 13. Then pressure P1 in room 15

is higher than the pressure P2 that exists in the space 14, the membrane 7 moves resp. 12 the valve disc 6 opposite the spring force FF in fig. 1 and 3 to the left. The strangulation 20 with its

reduced cross-sections co-determine the chronological course of the pressure change in the chamber 13 and thus also for the average opening and closing speed respectively s and s^ of the valve plate 6. Opening and closing of the valve follows an exponential function. With s and s^ it is possible to derive their average course.

In the first control condition a of the control valve 19 builds

the pressure that exists in the space 13, via the connection channels 16 and 17 again down to the pressure and the spring force FF closes the valve 4, as the membrane 7 resp. 12 displaces liquid from the first compartment 13 to the second compartment 14. The chronological course of this process also depends on the throttling 20, which will be explained in more detail later.

The impact sensor 10 is connected to a calculator 21. Furthermore, the device in fig. 1 a regulator 22 which controls the control joint 19, and whose output signal determines the control The state of the control valve 19. An output 23 from the regulator 22 is connected both to an input 24 to the calculator 21 and to the control valve 1.9. The connection from the stroke follower 10 to the calculator 21 goes to its input.

The regulator 22 in the embodiment of fig. 1 is designed as a two-point regulator with hysteresis. The signal that occurs at its_output 23 therefore has two defined states which determine the control state respectively a and b of the control valve 19 and whose duration T, T the calculator 21 determines as a ratio

based on this to calculate further physical data which will be explained later.

The desired value for the regulator 22 is derived from a differential link 26 whose first input 27 is connected to the stroke sensor 10, and whose second input 28 delivers a desired value for the average stroke s of the valve plate 6. This desired value is to be considered as the output signal from a superior regulator, which will be explained later.

From what has been said, it appears that the regulator 22 controls the control valve 19, which by utilizing the pressure difference Ap^over the servo member 1 affects the pressure in the room 13

and thus on the stroke s of the valve disc 6 in such a way that there is a regulation of the opening width of the valve 4 by means of the regulator 22.

The control valve 19 is suitably maneuvered by means of an electromagnet which is not shown in fig. 1, and which is affected by an output signal from the regulator 22. This electromagnet is dimensioned so that the control valve 19 in the de-energized state of the electromagnet short-circuits the diaphragm 7, i.e. connects the first and second chambers, respectively 13 and 14 with each other, whereby the valve 4 closes independently of the pressure difference Ap^..

From what has been said, it appears that the valve outside

its closed position never comes to rest, because in order to be able to comply with a certain average stroke s, the valve plate 6 must constantly oscillate back and forth about this value, as is shown for the stroke s in the diagram in fig. 2. During the time period T, the valve 4 opens, and during the time period T it closes. The length of the time periods T and Tv is based on the switching difference (hysteresis) for the two-point regulator 22, from the pressure difference Apvog from the cross-section of the throttle 20. The resistance of the throttle 20 has no influence on the measurement accuracy as long as the volume velocity in the throttle 20 is proportional to the pressure drop across the throttle. Appropriately, a capillary tube that fulfills this requirement within a wide flow range (Hagen-Poiseuil) serves as throttle 20. Inner cross-measurement and length of the capillary tube are co-determining for average opening and closing speed respectively s and s^ of the valve disc 6.

In the embodiment in fig. 1, an additional stopping device can also be used, which is shown dashed in the figure. In the connection channel 16 there is an additional valve 29 which can shut off the flow through the connection channel 16, and which is maneuvered from a control block 30, more specifically advantageously likewise by an electromagnet, however, so that the valve 29 releases the flow when the electromagnet is de-energized. The steering block

30 is connected to an output 33 via two inputs 31 and 32

from differential link 26, resp. with the calculator 21 and causes the valve 29 to close for flow at least part of the time, namely when the measured value agrees with the desired value for the regulator 22. The control block 30 receives the necessary commands for this via its inputs 31 and 32. Since then when the valve is closed 29 no longer can any exchange of liquid take place to or from the chamber 13, the valve plate 6 remains in the position it had when the valve 29 was closed, and that regardless of the position of the control valve

19. In the diagram on fig. 2 is the position of the additional valve

29 indicated by the bottom line, the "run" position means that the flow through the valve 29 is released and the regulation operation proceeds as described, while the "stop" position means that the flow through the valve 29 is closed and the valve disk 6 then remains in its momentary position. The flow restriction is triggered when the stroke s of the valve plate 6 has its mean value s (fig. 2).

With the help of the described stop device, it is possible to temporarily interrupt the regulation process and thus advance

and the feedback of the control valve 19 to reduce wear and save energy. The latter is of particular importance when there is a battery-powered device. In the same connection, it should be mentioned that, for energy-economic reasons, a bistable maneuvering of the control valves 19 and/or 29 is also conceivable, where each change of position is triggered by a short impulse.

In the design example in fig. 3 and 4 there is a control valve 34 which, in addition to the first and second control condition a resp.

b as mentioned for the control valve 19, also has a third control state c. In this third control state, the supply lines to all three rooms 13, 14, 15 are closed. In this application, a three-point regulator 35 serves as a regulator whose open command at the control valve 34 causes another control condition b during the time period T, and whose close command causes the first control condition a during the time period Tv, and whose neutral position when the control distance is equalized causes a third control condition c.

The control valve 34 with its three positions can be made up of different magnetically operated single valves. Among them, 7 also covers the use of the control valve 19

fig. 1 together with the additional control valve (stop valve) 29.

In the latter case, the flow in the control valve 29 in the neutral position of the three-point regulator 35 must be closed, and it is always closed at the location of the control block 30 (Fig. 1) by the output 36 from the three-point regulator 35 when the measured value at a differential link 37 of the three-point regulator 35 is equal to the desired value .

An advantageous device also appears if the control valve 19, 34 is designed as a rotary valve which is maneuvered by a motor driven by the regulator 22, 35. A reset device causes the control valve 19,

34 returns to the first position a automatically, that is

even if the power fails. A reset with a spring is suitable for this purpose, but purely electrical reset forms can also be considered, such as energy storage in a capacitor for reversing the operation in the event of a power failure.

In the design example in fig. 3 and 4, there is also arranged a noise magnitude transmitter 38 which influences the differential link 37. This transmitter is connected to the calculator 21 by a connection 39 and receives from it periodically recurring noise signals 41 which act in a changing direction and cause a pulse-like pre-tuning of the regulation circuit in open - and closing direction and a forced release of a measurement cycle with the time periods T and T for so, as described for fig. 1, to form the ratio e^, which will be described in the following.

The noise signals 41 emitted by the noise magnitude transmitter

38, and as in fig. 4 is shown as curve 40 as a function of time t, acts via the differential link 37 on the regulator 35

as time-limited desired value deviations. They trigger at the output 36 servo commands, and the resulting position of the control valve 34 during the time periods T and T is shown by another curve 42. Outside the time periods T and T^, the regulator 35 is balanced, and the control valve 34 is then in its middle position, i.e. in its third control state c. The positions of the control valve during the time periods T and T cause changes in the stroke s,

as shown by a third curve 43 for the stroke s, where the time periods T and T are also divided into T,, T which proceed after a noise signal 41 in the direction "open", and the time periods T„ , T« as K2 2

proceeds after a noise signal 41 in the direction "close". The calculator 21 receives via its input 24 the control commands that appear at the output 36, and forms the relationship eT on the basis of at least two successive noise signals 41, i.e. an open and a close command.

In a similar way as was described above with regard to the two-point regulator 22, it is also appropriate in the case of the three-point regulator 35 to save energy at least temporarily to suppress the commands from the noise magnitude transmitter 38, which the calculator, however, only performs when at least two successively calculated ratios e are mutual like. This condition is then appropriately maintained until the regulator 35, conditioned by the behavior of the regulation section, issues a control command again.

In both of the described embodiments it is possible

for the calculator 21 by interpreting the ratio eT and average stroke s of the valve plate 6 at least periodically on the basis of the chronological sequence of the signals that appear at the output 23 resp. 36 from the regulator 22 or 35 as well as at the impact sensor 10 to determine the pressure difference occurring at any time Apvover the servo link 1 and the volume velocity V in the servo link 1. The following relations serve this purpose:

where f.j and f2 denote functions given by constants, and s in the example with the two-point regulator 22 (fig. 1 and 2) denotes the mean value between the types s max resp. s K that is achieved

my

at the end of the time periods T and T , while the calculator 21

in the case of the three-point regulator 35 (fig. 3 and 4) calculates the ratio em from the values T-, T„ and T and T and s denotes 1 ii. \ 2

the type s that exists with balanced three-point regulator 35.

In what follows, a more detailed account will be given of the operation of the devices in fig. 1-4 and for the calculation bases for the pressure difference Ap^ and the volume velocity V.

Via the regulator 22 or 35, a specific valve opening position is regulated there, i.e. a specific average stroke s. This opening position represents, in the case of a heating control, the output signal from a supply temperature regulator. The desired value for average stroke s is entered at the input 28 of the differential link 26 or 37, and with both regulator forms, the regulator seeks 22 resp. 35 to adapt the measured value of medium type s to the desired value by forming a corresponding relationship for the positions of the control valve 19 resp. 34.

For the derivation of the functions f^s, e^) and ^ 2^ s'£t^

for determining the pressure drop Ap^ and the volume velocity V, the following considerations serve:

For valve 4, the force equation applies

It follows from this: For the valve 4, during the time period T, i.e. when the chamber 15 is connected to the chamber 13 via the throat 20, the pressure equation applies

Substitution of II in III follows:

According to Hagen-Poiseuil, in a pipe with laminar flow: where for the fraction you can insert the size R and for

From formulas IV and VI follows:

During the time period T., i.e. when room 13 is connected to room 14, applies: and according to formula II is

Resolved with respect to R this gives: Furthermore, it follows from formulas VII and VIII that

Reshaped provides this based on

The side where the expression in parentheses in formula IX applies is obtained from equation IX and thus and finally

The calculator 21 can thus continuously or only periodically according to equation X determine the pressure difference Ap^ across the valve 4 by determining the average stroke s and forming the ratio without the need to use pressure sensors for this, because the other quantities in equation X are determined by the dimensions of the servo link 1. With knowledge of the pressure difference Apvover the servo link, it is also possible to determine the volume velocity V, which will be explained in more detail in the following:

For the speed v of the flow through a valve generally applies:

The volume velocity V in the servo joint 1 thus becomes:

and one thus obtains: From the equations X and XI it follows from which the calculator can also determine the instantaneous volume velocity V in the servo link 1. In the devices described, the calculator 21 determines the stroke s and the setting commands for the regulator 22, 35, and the ratio is formed from the latter. However, the invention also includes any application of another ratio. Thus, it is e.g. possible to loop the input 24 at the calculator 21 and only influence this with the signals from the impactor 10. The calculator 21 then determines from the rates of change s and s^ of the valve disc 6 during an opening or during the subsequent closing impulse a ratio

From this expression, it is possible in the same way as described for, taking into account the average stroke s, to calculate the differential pressure Apvog and the volume velocity v".

The two design examples described earlier with reference to fig. 1 and 3, does not allow the calculator 21 to be included in the regulation circuit. In both examples, the regulator 22 or 35 regulated a specific middle stroke. This means that a change in the pressure rise Pp above the pump as marked in the top curve in fig. 2, leads to a change in the time ratio e and thus to a stroke change which the regulator again corrects. This means that a change in the pressure rise Pp across the pump, e.g. in case of load changes, manifests itself as a change in the volume velocity V.

When using the described device in accordance with fig. 5 is also obtained with pressure changes originating from the pump, as the device is designed for regulating the volume rate V and has at least one regulator 22, 35 which compares its desired value with the measured value of the volume rate V determined by the calculator 21. In this embodiment, the calculator 21 is also drawn into the control circuit and simultaneously delivers values for the pressure difference Apvog the volume flow Vy which can also be interpreted (e.g. for measuring heat quantities). Fig. 5 illustrates such an application with a two-point regulator 22 in accordance with fig. 1, but a three-point regulator can also be used there. The output 23 from the regulator 22 acts as described for fig. 1 on the servo member 1 and via the input 24 the calculator 23. The control valve is not shown in fig. 5. The stroke s of the valve disc 6 is determined by the calculator 21 at the input 25. An output 44 from the calculator 21 acts on the differential link 26. The differential link 26 compares the measured value of the volume velocity V supplied by the calculator 21 with the desired value at the input 28. Thereby the influence of any change in the pressure rise Pp over the pump compensated.

In the design example in fig. 6, the device is used for cascade regulation of a space heating. It comprises several regulators, each with an associated pre-connected differential link. A first regulator 45 which acts on the control valve 19 or 34 (fig. 1 resp. 3) regulates the stroke s,

as was described for the design examples in fig. 1-

4. A connection 53 reports back the stroke measurement value s to the regulator 45, and at the inputs 24 and 25 the signals from the regulator 45 for forming the ratio e T resp. the signal which corresponds to mean strokes s. Another regulator 47 compares the volume velocity V^ determined by the calculator 21 with the desired value. The calculator is also located here in the control circuit. Its signal at the output 44 forms the measured value for the regulator 47. Hydraulically connected to the servo link 1 is one heating series of several radiators 48 with a flow and a return which are not shown in fig. 6, and from their temperatures ■&„ and $n the temperature difference A-9- is formed.

Together with the volume velocity determined by the calculator 21

Vjdetermines a calculation term 49 which likewise belongs to the calculator 21, the momentarily released amount of heat P which a third regulator 50 takes as a measured value. A temperature sensor 51 reports the measured value of the room temperature to a fourth regulator 52/whose output acts on the regulator 50.

The regulators 47, 50 and 52 are all superior to the first regulator 45 which acts on the control valve 1. In this way, respective disturbing quantities that may occur are deregulated before they can express themselves via the room temperature.

Each of the devices described can be designed for

to determine the heating costs for hot water heating. For this purpose, the respective amount of heat is determined taking into account the temperature difference A& between flow temperature ■& and return temperature as well as the volume velocity

V.

In this connection, the main advantage of the object of the invention is that it becomes possible via the servo link 1, which is still needed for the regulation process, to determine the volume velocity V without needing any additional measuring device for the differential pressure Apvs as in the older technique.

The low-cost determination of the pressure difference Apvover the servo link of a control section and of the volume velocity V in the servo link, as well as the possibility of simultaneous heat quantity measurement using a calculator, opens up many further areas of application. Among these can be mentioned: Determination of the heat output of individual consumers using the centrally arranged calculator in connection with individually regulated groups of heaters that are fed from a common supply. It is appropriate here to lay their servo link to the return and arrange the measuring point for the return temperature in the servo link. The connection between the calculator and the servo links takes place via a data bus or by means of a wireless transmission device for battery-operated control valves. In such a system, a pump regulation can also be considered, because thanks to the fact that the pressure difference Ap^ over each servo link is also determined, the calculator will be able to adapt the pump's effect according to the occurring pressure differences Apv, whereby energy is saved and any noise in case of large pressure differences is prevented.

Furthermore, the device can be used for regulation and heat quantity measurement for a heating customer connected to a district heating system. This offers the advantage that, at the same time, it is possible to comply with additional limit values prescribed by the heating plant and for measuring technical reasons. Such limit values are: minimum return temperature maximum flow temperature minimum temperature difference A& as well as maximum and minimum volume velocity V and maximum and minimum heat output P .

Claims (1)

1. Device for determining the volume rate of a liquid medium's flow through a servo link which is designed as a through valve and has an inlet and an outlet and is part of a regulation section, comprising a stretchable link that affects the opening movement of a valve plate of the through-valve against a spring force and an impact sensor to determine the position of the valve plate, from which it is possible to derive the volume velocity via the pressure difference occurring across the passage valve, characterized by that there is a control valve (19, 34) which is controlled by means of at least one regulator (22, 35, 45) and connects a of the stretchable link (7, 12) limited first space (13) of the passage valve (4) via connection channels (16, 17, 18) in a first stable control condition with another chamber (14) and in another stable control condition with a third chamber (15), of which the second chamber (14) has the outlet connection (3) and the third chamber (15) the inlet connection (2), that the effective areas of the stretchable joint (7, 12) and the valve disc (6) as well as the spring force .F are chosen so that the pressure difference Apv arising across the passage valve (4) in another control condition opens the valve disc (6) and the spring force Fp closes the valve disc (6 ) in the first control state, and that the stroke sensor (10) is connected to a calculator (21) to determine the pressure difference Ap^ and/or the volume velocity V on the basis of the output signals of the regulator (22, 35, 45) and the stroke sensor (10). 2. Device as stated in claim 1, characterized in that the connection channels (16, 17, 18) have at least one bottleneck (20). 3. Device as stated in claim 2, characterized by that the only bottleneck (20) is. arranged in the connecting channel (16) which goes out from the first room (13), and consists of a capillary tube whose free width and whose length co-determines an average opening and closing speed s resp. s^ of the valve disc (6) . 4. Device as stated in claim 1, characterized by that the calculator (21) is arranged for based on the time period T and during which the valve disc (6) opens or closes, to form a relationship and from this, taking into account an average stroke s of the valve disc (6) to determine the pressure drop Ap^ and the volume velocity V as functions f^ resp. of s and e^ , as applicable where s denotes the mean value between two types s ms x and s,ic min which occurs at the end of the periods T or T K<*> 5. Device as specified in claim 4, characterized in that pressure drop and volume flow V are determined according to the formulas where F„r(s) denotes the spring force at the instantaneous value of stroke s of the valve plate (6), Arø the effective area of the diaphragm (7, 12), Ay the effective area of the valve plates (6), p the density of the flow medium and fv (s) the valve characteristic of the servo member (1). 6. Device as stated in claim 5, characterized by that the regulator (22) is designed as a two-point regulator with hysteresis and the control valve (19) has two stable states. 7. Device as stated in claim 5, characterized by that the control valve (34) also exhibits a third stable control state where all connection channels (16, 17, 18) to the three chambers (13, 14, 15) of the servo member (1) are closed, that there serves as regulator (35) a three-point regulator whose open commands at the control valve (34) cause a different control state, and whose close commands cause a first control state, and whose neutral position in case of equalized regulation firing causes a third control state, that there is a transmitter (38) for disturbing quantities (noise quantity transmitter) to emit periodically recurring disturbing signals (41) which act in a changing direction to impulsively bias the control circuit in the opening and closing direction, at the same time that the calculator (21) determines the ratio e in the smallest on the basis of two successive disturbing signals (41) (open and close), and that the calculator (21) by successive equal conditions at least temporarily suppresses the commands of the noise magnitude generator (38). 8. Device as specified in claim 6, characterized by that an electromagnet is used to operate the control valve (19) which is affected by the signal at the output of the regulator (22), and that the control valve (19) connects the first room (13) with the second room (14) in a de-energized state. 9. Device as stated in claim 8, characterized by that in the connection channel (16, 17) which exits from the first room (13), there is a further valve (29) to close the connection channel (16) during at least part of the time periods when the regulator's (22) measurement value is equal to the desired value. 10. Device as specified in claim 9, characterized by that the further valve (29) is also maneuvered by means of an electromagnet and in a de-energized state releases the through-flow. 11. Device as stated in claim 6 or 7, characterized by that the control valve (19, 34) is designed as a slide valve which is maneuvered by a motor drive controlled by the regulator (22, 35), and that there is a reset device to forcibly reset the control valve (19, 34) to the position that connects the first and second rooms (13 or 14). 12. Application of a device as specified in one of claims 1-11, for regulation of the volume velocity V, in that there is at least one regulator (22) which compares its desired value with the measured value of the volume velocity V determined by the calculator (21). 13. Use of a device as specified in one of claims 1-11, as cascade regulation, comprising several regulators (47, 50, 52) which are all superior to the regulator (45) which acts on the control valve (19, 34). 14. Application of a device as stated in one of the claims 1-11, for heat quantity measurement in a hot water heating, where the calculator (21) taking into account the temperature difference A$ between a flow temperature $ and a return temperature as well as the volume velocity V additionally determines extracted amount of heat.