EP2304325B1 - Method for hydraulic equalisation and regulation of a heating or cooling unit and equalisation and regulation valve for same - Google Patents

Description

Technical area

The present invention relates to a balancing and control valve for a heating or cooling system and a method for the hydraulic balancing of such a balancing and control valve in a strand of a heating or cooling system.

State of the art

The hydraulic adjustment of a heating or cooling system is made before the system is handed over to the customer. The system must be fully installed and in operation. The aim is to distribute the medium supplied by the central pump as needed to the various zones of the system. The adjustment is usually made only at one operating point, namely at full load. This means for such a system, that all control valves are open to the maximum. In this state, the speed of the pump and the position of balancing throttles or balancing valves, which are upstream or downstream of the actual control valves, are adjusted so that the flow values set by the designer are reached in each line. The speed of the pump should be set as low as possible, but high enough to reach all the required flow rates.

So you go physically from valve to valve, where it measures the flow, rotates at the balancing choke until the flow takes the desired value. For flow measurement, a differential pressure gauge is often used. The pressure loss is measured over a known resistance, eg an orifice plate or a heat exchanger. Alternative to Differential pressure measurement can also use a mobile ultrasonic flowmeter, which can be mounted outside the piping.

From the US 2004/182443 It is known that this approach is improved in that no longer two valves, a balancing valve and a control valve are provided, which are provided in series to a load in a train, but a combined balancing and control valve can be used. However, the valve described in this step is complicated and requires those skilled in the art to use various inserts to achieve the goal of hydraulic balancing. Also, the control of this combined balancing and control valve is not easy.

DE 40 19 503 A1 discloses a control valve for a heating system, in which by using a valve lift / flow correction curve, the flow in a string can be adapted to the hydraulic and thermodynamic conditions of the heating system.

Out EP 0 301 568 An autocalibration method for a control valve is known in which the effective travel of the valve is detected and the control range is limited to this effective travel. The effective travel is defined as the range of the total travel between 5% and 95% of the maximum flow. This document is not concerned with the task of hydraulic balancing.

Presentation of the invention

The invention is now based on the insight that said prior art hydraulic balance adjustment is made only with open control valves to determine the minimum necessary pump delivery required at full load to achieve all required flows in the individual strands , The disadvantage then arises that in strands with already throttled balancing valve (balancing valve), a larger part of the control range of the control valve is lost. If the balancing valve is partially closed, namely the overall characteristic (k _V - flow characteristic) of the strand at a larger opening of the control valve, ie in its upper control range, flattened. In contrast, the overall characteristic is steeper with smaller opening of the control valve, ie in its lower region. This deformation of the characteristic deteriorates the control behavior for this line, because on the one hand in the lower control range, the resolution is worse, and on the other hand, the total circle gain over the control range is not constant. The variable loop gain actually requires variable control parameters. This makes the tuning of the controller difficult, especially since variable parameters are usually not provided in the controllers used.

It is therefore an object of the present invention to overcome this disadvantage of the prior art and to connect hydraulic balancing and control in a simple manner adjustable control technology. In particular, it is an object of the present invention to design the overall characteristic curve, that is to say the characteristic curve of the control valve with a folded characteristic of the connected load, for example a heat exchanger, for a simpler and better control.

According to the present invention, these objects are achieved in particular by the elements of the independent claims. Further advantageous embodiments are also evident from the dependent claims and the description.

Instead of throttling at a balancing valve (balancing valve), the setting range of the actual regulating valve is restricted. In addition to this restriction, the valve control is also notified, so that the signal range can be automatically mapped to the new setting range. This leaves a 100% dynamic range for the controller.

A method for hydraulic balancing a balancing and control valve in a train of a heating or cooling system can be used if such a balancing and control valve and a load is provided. A strand of the heating or cooling system is flowed through by a medium. In this case, a control value for the balancing and control valve is determined, in which a predetermined flow value of the medium, which is less than the maximum flow value, is achieved in the strand. This control value is defined and set as "maximum control value". The adjustment range of the balancing and control valve is then defined as the range between the set "maximum control value" and the position with the balancing and control valve closed. The original signal control range of the balancing and control valve is then mapped to the newly defined setting range. This results in full dynamics with reduced maximum control value.

Advantageously, the valve characteristic is an equal percentage characteristic in order to produce a linear dependence in interaction with a connected heat exchanger. Due to the restriction of the setting range, an equal percentage valve characteristic at 100% setting range is also in the balanced state, ie with a smaller setting range, for example 60%, equal to the percentage. This applies over the largest area of the restricted setting range.

Furthermore, a predetermined lower control range can be designed linear in order to ensure better control of the small valve openings. This division of the control range over a continuously differentiable transition allows the combination of the advantageous equal percentage valve characteristic in the large opening area to avoid a flattening of the slope at high control deflections, with the linear flat characteristic in a predetermined lower control range.

Setting the "maximum control value", e.g. can be set in the form of a limiting angle, can be done manually directly on the actuator, or electrically via the control signal, which is also used in control mode.

Storing the "maximum control value", i. the determined and set position of the valve as a new maximum value can be made by pressing a button directly on the drive, or electronically by sending a bus command. This command can be sent either from a service tool or from the building management system.

Brief description of the drawings

• Figur 1 zeigt ein Diagramm, welches schematisch eine Kennlinie eines herkömmlichen Regelventils, das mit einem Abgleichventil in Serie geschaltet ist, und eine Kennlinie eines erfindungsgemässen Abgleich- und Regelventils zeigt.
• Figur 2 zeigt ein Diagramm, das schematisch eine Kennlinie eines Wärmetauschers als Last, eine Kennlinie eines erfindungsgemässen Abgleich- und Regelventils und die Gesamtkennlinie eines Strangs zeigt.

Hereinafter, an embodiment of the present invention will be described by way of example. The example of the embodiment is illustrated by the following attached figures:

• FIG. 1 shows a diagram which schematically shows a characteristic of a conventional control valve, which is connected in series with a balancing valve, and a characteristic of a balancing and control valve according to the invention.
• FIG. 2 shows a diagram showing schematically a characteristic of a heat exchanger as a load, a characteristic of a balancing and control valve according to the invention and the overall characteristic of a strand.

Ways to carry out the invention

The FIG. 1 shows a schematic of a characteristic curve 10 of a conventional control valve, which is connected in series with a balancing valve, and a characteristic curve 20 of an inventive balancing and control valve.

It can be seen that the pitch 11 of the characteristic curve 10 of the conventional control valve is much steeper in the lower control range, ie at values of, for example, 10 to 20%, than the pitch 21 of the characteristic curve 20 of a balancing and control valve according to the invention in the range between 0% and 30%. This allows a more accurate control in the lower control range and thus prevents greater control oscillations. In most cases, in the valves according to the prior art and in the balancing and regulating valve described here, the slope 11 or 21 is still connected to a region 13 without incline, also called dead angle or dead zone, here at 0% to 10%.

Further, it can be seen that the slope 12 of the curve 10 of the conventional control valve in the upper control range, here 80% of the adjustment range very flattens out and comes in, by way of example here, against a percentage k _V value of 25% obtained by the pre- or downstream balancing valve is specified as the maximum value. On the other hand, there is still an increasing and therefore sufficient slope 22 of the characteristic curve 20 of the balancing and regulating valve according to the invention, so that the k _V value of the strand is only reached with full utilization of the control range of 100%.

Advantageously, the characteristic curve 20 of a balancing and regulating valve for this method and apparatus is equal to percentage. With an equal-percentage characteristic, the same input variable changes cause the same percentage output variable changes over the entire cycle Control range. Particularly advantageous is an equal percentage characteristic with an equal percentage factor of over 4, for example 4.5.

The resulting benefit can be derived from the FIG. 2 which shows a diagram which schematically shows a characteristic curve of a heat exchanger 30 as a load, a characteristic curve 20 of a balancing and regulating valve according to the invention and the overall characteristic curve 40 of a strand. With the equal percentage characteristic of the balancing and control valve, the exactly opposite designed characteristic curve 30 of a heat exchanger connected as a load can be compensated, so that then an overall characteristic curve 40 results, which is substantially linear.

Since both the characteristic curve 20 of the valve and the characteristic of the load 30 are substantially scaled at a lower presetting, the resulting control characteristic 40 of a strand remains essentially linear, or can be viewed as such by a control unit.

$${\mathrm{k}}_{\mathrm{V}}{|}_{\frac{\mathrm{\alpha }}{{\alpha }_{\mathrm{100}}}\ge \frac{\mathrm{1}}{{\mathrm{n}}_{\mathrm{gl}}}}={\mathrm{k}}_{\mathrm{V}\mathrm{100}}\cdot {\mathrm{e}}^{{\mathrm{n}}_{\mathrm{gl}}\cdot \left(\frac{\alpha }{{\alpha }_{\mathrm{100}}}-\mathrm{1}\right)}$$

In a further advantageous embodiment, the equal-percentage characteristic 20 addressed here is modified. $${\mathrm{k}}_{\mathrm{V}}{|}_{\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{\mathrm{100}}}\le \frac{\mathrm{1}}{{\mathrm{n}}_{\mathrm{gl}}}}={\mathrm{<figure-callout\; id="100"\; label="k\; V"\; filenames="imgf0001.png"\; state="\{\{state\}\}">k\; </figure-callout>}}_{\mathrm{V}}\cdot \frac{\alpha }{{\alpha }_{\mathrm{100}}}\cdot {\mathrm{n}}_{\mathrm{gl}}\cdot {\mathrm{e}}^{\mathrm{1}-{\mathrm{n}}_{\mathrm{gl}}}$$

$${\mathrm{k}}_{\mathrm{V}}{|}_{\frac{\mathrm{\alpha }}{{\alpha }_{\mathrm{100}}}\ge \frac{\mathrm{1}}{{\mathrm{n}}_{\mathrm{gl}}}}={\mathrm{<figure-callout\; id="100"\; label="k\; V"\; filenames="imgf0001.png"\; state="\{\{state\}\}">k\; </figure-callout>}}_{\mathrm{V}}\cdot {\mathrm{e}}^{{\mathrm{n}}_{\mathrm{gl}}\cdot \left(\frac{\alpha }{{\alpha }_{\mathrm{100}}}-\mathrm{1}\right)}$$

der Quotient aus Öffnungswinkel α zum eingestellten maximalen Öffnungswinkel α_100, also der Wert, der in Figur 1 als Position Signal auf der Abszisse aufgetragen wird; und k_V100 der Durchflusswert bei vollkommen offenem maximalen Öffnungswinkel. Dann wird die angestrebte Kennlinie in einem oberen Öffnungsbereich 22 durch eine Exponentialfunktion beschrieben. Der Parameter n_gl (engl. n_ep) ist ein Mass dafür, wie stark die Kennlinie gekrümmt ist. Da Exponentialfunktionen nie durch den Nullpunkt gehen, wird diese Definition der Kennlinie im unteren Bereich 21 linear ersetzt. Der Übergang vom linearen zum exponentiellen Teil ist stetig differenzierbar und er wird durch den Reziprokwert von n_gl vorgegeben. Die gesamte Kennlinie wird "gleichprozentig" genannt (engl. "equal percentage", manchmal "modified equal percentage"). Bei einem hier beschriebenen Ausführungsbeispiel ist n_gl = 4.5. Vorteilhaft für die Funktion der Abgleichs mit einem gleichprozentigen Ventil ist die gegenüber dem Stand der Technik von n_gl = 2 bis 4 die stärkere Krümmung. Vorteilhaft sind gleichprozentige Ventile mit einem Wert von n_gl von 4.5 bis 6 oder 7. Damit verschiebt sich gleichfalls der Bereich des Übergangs der Kurve in den linearen Teil zu kleineren $\left(\frac{\alpha }{{\alpha }_{100}}\right)$

- Werten. Mit anderen Worten bei einer Beschränkung des maximalen Stellbereichs bei einem vorgegebenen Ventil ergibt sich eine flachere Steigung im linearen Bereich als beim Stand der Technik, womit eine genauere Regelbarkeit möglich wird.Here is the expression $\left(\frac{\alpha }{{\alpha }_{100}}\right)$

the quotient of opening angle α to set maximum opening angle α _100, ie the value in FIG. 1 when Position signal is plotted on the abscissa; and k _{V100 is} the flow rate at fully open maximum opening angle. Then, the aimed characteristic in an upper opening portion 22 is described by an exponential function. The parameter n _gl (English n _ep ) is a measure of how strongly the curve is curved. Since exponential functions never pass through the zero point, this definition of the characteristic in the lower region 21 is replaced linearly. The transition from the linear to the exponential part is continuously differentiable and it is given by the reciprocal of n _gl . The entire characteristic curve is called "equal percentage" (sometimes "modified equal percentage"). In an exemplary embodiment described here _ngl = 4.5. Advantageous for the function of the adjustment with an equal percentage valve is compared to the prior art of n _gl = 2 to 4, the stronger curvature. Advantageously, equi-percent valves with a value of n _gl of 4.5 to 6 or 7. This also shifts the range of the transition of the curve in the linear part to smaller $\left(\frac{\alpha }{{\alpha }_{100}}\right)$

- values. In other words, a limitation of the maximum control range for a given valve results in a flatter slope in the linear range than in the prior art, which allows a more precise controllability.

The function of a hydraulic balancing a heating or cooling system is then constructed as follows on the components of the system. Such a heating or cooling system comprises at least one pump and a plurality of strands, each having a balancing and control valve and a load, wherein the valve and load are connected in series one behind the other. The load is usually a heat exchanger.

A maximum control value is then set for each of the trim and control valves so that predetermined flow values in each leg be achieved. After this setting step, the adjustment range of each balancing and control valve is defined as the range between the set maximum control value and the position with the balancing and control valve closed. Then in the control circuit of the heating or cooling system of the signal control range of each balancing and control valve is mapped to the newly defined setting range, so that again the full signal control width of 100% is available, which is applied to a reduced control range. In other words; by the advantageously linear initial range and the subsequent exponential characteristic can be ensured by mapping the signal control range of each balancing and control valve to the newly defined setting range, that there is a reasonably controllable range for small Stellgrösseren because the slope of the linear region remains flat and through the then exponentially rising curve for large control ranges up to the maximum out no saturation of the control occurs.

Advantageously, in the said electronic control unit, the maximum control values of the individual balancing and control valves can be stored, which can then be transmitted as setting signals to the balancing and control valves after this storage in order to determine the maximum value of the valve opening.

In the design of the heating or cooling system balancing and control valves and elements acting as a load are advantageously used, each having its own characteristic, so that the resulting from load and balancing and control valve overall characteristic of a strand is substantially linear. Since the load characteristic usually has a shape like the characteristic curve 30 in FIG FIG. 2 has, it is advantageous that each balancing and control valves are used, which have an equal percent valve characteristic and there again preferably a characteristic with a n _gl of 4.5.

In addition to the adjustment of a heating or cooling system with multiple strands, the balancing and control valve according to an embodiment of the invention can also be useful on its own. It is then still set a maximum control value for this balancing and control valve; this adjustment being made by an adjustment knob, for example potentiometrically. It is advantageous that the maximum control value is not just a stop, but a maximum adjustable angle or other manipulated variable of the valve, so that a predetermined maximum flow value is achieved in the strand of this valve. This maximum value can also be stored in a, for example non-volatile, memory of a control and regulating circuit of the valve. After this setting step, the setting range in this control and regulating circuit is defined as the range between the set maximum setting value and the position when the balancing and regulating valve is closed. Then, in the control circuit of the heating or cooling system, the signal control range of this balancing and control valve can continue to be addressed over the full signal control width of 100%, which is then actually applied to a reduced in the valve control range. The mapping to the newly defined control range can thus take place exclusively in the balancing and control valve, which makes it possible to replace individual valve combinations of string valve and control valve in an older heating or cooling system by a balancing and control valve according to the invention, if the response is compatible by the control circuit. Signal control range is understood to mean the range of input signals (digital or analog) for the balancing and control valve with which a control unit can respond to this valve to a maximum, which usually corresponds to values between 0% and maximum 100% opening of the valve. In the invention, this maximum signal control range just scaled to the full reduced adjustment range of the balancing and control valve responsive and there is no interval of the signal control range, which is lost.

In this case, such a balancing and control valve can work autonomously in a train when it is acted upon by a conventional control unit of a heating or cooling system with a drive signal between 0 and 100%. But it can also work with a control unit of a heating or cooling system according to another embodiment of the invention, in which the balancing and control valve itself does not know or store a maximum threshold value, but in this control unit these maximum control values are stored and then the drive signal for a balancing and control valve just does not have a signal value between 0 and 100% but covers only a predetermined by the maximum control value range of, but then with a signal value resolution of 100%.

In the FIG. 1 an example is drawn. In the case of a valve characteristic 20, the maximum control value is set to 75% in one line, for which the reference symbol S ₇₅ has been used. A control signal generated by a control unit of 60% then does not result in an opening of the valve corresponding to the characteristic at the position A _60/100 , but the k _V value results just at the position A _60/75 , which is 60% of a resulting from the maximum control value of 75% given control range, that is at the position signal of 45 percent (= 60% * 75%)

LIST OF REFERENCE NUMBERS

10

Characteristic of a known control valve

11

Slope in the lower control range in the known control valve

12

Slope in the upper control range in the known control valve

13

Slope in a lowermost control range in the known control valve

20

Characteristic of a balancing and regulating valve for a system according to the invention

21

Slope in the lower control range in the embodiment

22

Slope in the upper control range in the embodiment

30

Characteristic of a heat exchanger for a system according to the invention

40

Overall characteristic of a system according to the invention

Claims (13)

1. A method for the hydraulic balancing of a branch of a heating or cooling system, wherein the branch comprises a balancing and regulating valve and a load, comprising the following method steps:

   causing a medium to flow through the branch;

   determining a setpoint value for the balancing and regulating valve, at which setpoint value a predetermined throughflow value is reached in the branch, wherein the predetermined throughflow value is lower than a maximum possible throughflow value through the branch;

   restricting the operating range of the balancing and regulating valve to the range between the determined setpoint value and a position in which the balancing and regulating valve is closed; and

   mapping the signal regulating range of the balancing and regulating valve onto the newly defined operating range.
2. The method as claimed in claim 1, characterized in that the balancing and regulating valve has an equal-percentage valve characteristic curve.
3. The method as claimed in claim 1, characterized in that the balancing and regulating valve has a valve characteristic curve which has an at least approximately linear profile in a first, lower operating range and which has an equal-percentage profile in a second, upper range.
4. The method as claimed in claim 3, characterized in
   that, if the expression $\left(\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{100}}\right)$

   

   indicates the quotient of the setpoint value α and the set maximum setpoint value α₁₀₀ and n_gl indicates the characteristic equal-percentage number, the valve characteristic curve, in a first range of $\left(\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{100}}\right)$

   

   
   lower than the reciprocal value of n_gl is a linear characteristic curve and, in the remaining second range of $\left(\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{100}}\right)$

   

   higher than the reciprocal value of n_gl, is an exponential characteristic curve: $$k_V{|}_{\frac{\alpha }{{\alpha }_{100}}\le \frac{1}{{\mathit{n}}_{\mathit{gl}}}}=k_{V100}\cdot \frac{\alpha }{{\alpha }_{100}}\cdot {\mathit{n}}_{\mathit{gl}}\cdot e^{1-{\mathit{n}}_{\mathit{gl}}}$$

   

   $$k_V{|}_{\frac{\alpha }{{\alpha }_{100}}\ge \frac{1}{{\mathit{n}}_{\mathit{gl}}}}=k_{V100}\cdot e^{{\mathit{n}}_{\mathit{gl}}\cdot \left(\frac{\alpha }{{\alpha }_{100}}-1\right)}$$

   
5. The method as claimed in claim 4, characterized in that n_gl is higher than 4.5, in particular higher than 5.
6. A method for hydraulic balancing of a heating or cooling system comprising at least one pump and a plurality of branches, comprising the steps:

   causing a medium to flow through the heating or cooling system at a predetermined pump capacity; and

   carrying out of the method as claimed in one of claims 1 to 5 for each of the branches.
7. The method as claimed in claim 6, characterized in that the maximum setpoint values of the individual balancing and regulating valves are stored in an electronic control unit, and that, after the storing operation, setting signals are transmitted from the control unit to the balancing and regulating valves in order to transmit the maximum value of the valve opening.
8. A balancing and regulating valve for a heating or cooling system, adapted to be mounted as a balancing and regulating valve in a branch in series with a load, the balancing and regulating valve being configured such that a maximum setpoint value can be set so that a predetermined throughflow value in the branch is achieved,
   characterized
   in that the balancing and regulating valve is configured such that the maximum setpoint value of the valve can be set as a part value with respect to a complete opening of the valve,
   in that the operating range of the balancing and regulating valve can be set as the range between the set maximum setpoint value and the position when the valve is closed,
   in that the signal regulating range of the balancing and regulating valve can be mapped onto the newly defined operating range, and
   in that the balancing and regulating valve comprises a control unit in which the maximum setpoint value can be input manually or electrically/electronically for defining the operating range of the balancing and regulating valve as arranged between the set maximum setpoint value and the position when the balancing and regulating valve is closed, and wherein, further, the control unit is designed for mapping the signal regulating range of the balancing and regulating valve onto the newly defined operating range.
9. A device for the hydraulic balancing of a heating or cooling system, wherein the heating or cooling system comprises at least one pump and a multiplicity of branches, each with a load, wherein the device comprises a plurality of balancing and regulating valves, each of said balancing and regulating valves being adapted to be mounted in a branch in series with the corresponding load and being configured such that a maximum setpoint value can be set so that a predetermined throughflow value in the branch is achieved,
   characterized
   in that each of the balancing and regulating valves is configured such that the maximum setpoint value of the valve can be set as a part value with respect to a complete opening of the valve,
   in that the operating range of each balancing and regulating valve can be set as the range between the set maximum setpoint value and the position when the valve is closed,
   in that the signal regulating range of each balancing and regulating valve can be mapped onto the newly defined operating range, and
   in that the device comprises a control unit in which the maximum setpoint values, delivered manually or electrically/electronically by said balancing and regulating valves, can be input for defining the operating range of each of these balancing and regulating valves as the range between the set maximum setpoint value and the position when the balancing and regulating valve is closed, wherein the control unit is designed, further, for mapping the signal regulating range of each balancing and regulating valve onto the newly defined operating range.
10. The device as claimed in claim 9, characterized in that at least one such balancing and regulating valve has an equal-percentage valve characteristic curve.
11. The device as claimed in claim 9, characterized in that at least one such balancing and regulating valve has a valve characteristic curve which has an at least approximately linear profile in a first, lower operating range and which has an equal-percentage profile in a second, upper range.
12. The device as claimed in claim 11, characterized in that, if the expression $\left(\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{100}}\right)$

    

    indicates the quotient of the setpoint value α and the set maximum setpoint value α₁₀₀ and n_gl indicates the characteristic equal-percentage number, the valve characteristic curve of said balancing and regulating valve, in a first range of $\left(\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{100}}\right)$

    

    lower than the reciprocal value of n_gl, is a linear characteristic curve and, in the remaining second range of $\left(\frac{\mathrm{\alpha }}{{\mathrm{\alpha }}_{100}}\right)$

    

    higher than the reciprocal value of n_gl, is an exponential characteristic curve: $$k_V{|}_{\frac{\alpha }{{\alpha }_{100}}\le \frac{1}{{\mathit{n}}_{\mathit{gl}}}}=k_{V100}\cdot \frac{\alpha }{{\alpha }_{100}}\cdot {\mathit{n}}_{\mathit{gl}}\cdot e^{1-{\mathit{n}}_{\mathit{gl}}}$$

    

    $$k_V{|}_{\frac{\alpha }{{\alpha }_{100}}\ge \frac{1}{{\mathit{n}}_{\mathit{gl}}}}=k_{V100}\cdot e^{{\mathit{n}}_{\mathit{gl}}\cdot \left(\frac{\alpha }{{\alpha }_{100}}-1\right)}$$

    
13. The device as claimed in claim 12, characterized in that the value n_gl of the balancing and regulating valve is higher than 4.5, in particular higher than 5.

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