DE3211814C1 - Circulation pump for heating systems - Google Patents

Description

30th

The invention relates to a circulation pump for heating systems, the motor of which can be set to at least two predetermined speeds / Ji, / J ₂ ... n-, by winding switching, of which the lowest speed m is designed to operate the system in an economy level and each higher speed nz ... m is assigned to another operating level of the system.

In most cases, circulators are running at a constant speed regardless of the speed required output of the heating system. However, this mode of operation is wasteful electrical energy, since the flow rate can easily be reduced at part load of the heating system could, which is possible simply by lowering the pump speed. That this is considerably more electrical Energy can be saved, becomes particularly clear when you consider that the Drive power is proportional to the third power of the speed. So that means, for example like this by reducing the pump speed by 20% to 80%, the electrical drive power to around 50% can be lowered.

However, this option of saving energy, which is offered by a turbomachine, can only then be achieved Use it sensibly if you choose an electric drive whose speed changes with as little loss as possible can be. One such drive is the electric motor, whose speed is increased by switching the windings different fixed values can be set, the disadvantage of which, however, is that the Speed only switched in steps and not arbitrarily to a certain, determined as optimal and Working speed lying between the fixed predetermined speed values can be regulated.

There are infinitely variable electric motors such. B. those with frequency converters. But these drives are in the case of circulating pump units with the relatively low engine power for economic reasons Cannot be used for reasons, especially since their price is a multiple of the pump price.

Furthermore, phase control systems for stepless regulation of the engine speed are known, which are in the Compared to speed controls with frequency converters are much cheaper, but have the disadvantage have that the efficiency of the drive is worse according to the lowering of the speed, so that such controls are not readily used to control a pump motor can, if one is particularly striving to save electrical energy.

The object of the invention is to provide a circulation pump for heating systems, whose Working speed in the entire specified speed range continuously and with good efficiency to the the optimal value can be set according to the system conditions.

This object is achieved according to the invention in that in the above-mentioned circulation pump the engine speed, starting from one of the higher specified speeds, continuously in the direction of next lower speed can be adjusted to a working speed adapted to the respective system conditions is.

So if you specify the speed range from / 20 with the speed zero to m as the highest possible speed when designing a circulation pump, this range is divided into certain switching or speed levels, i.e. into the ranges / 20 to n \, n \ to / 22 ... J2 / -1 to n " where the upper speeds m, n ₂ ... m belonging to these stages can be set in the usual way with good efficiency by switching the windings. On the basis of such a predetermined speed, according to the invention, it should be possible to regulate continuously in the direction of the next lower speed until one comes to the working speed n _{x lying in the relevant speed step range.}

In this case, the stepless control is only used to bypass a single switching or switching point. Speed stage and thus a relatively small speed range needed. This has the advantage that on the one hand, cheap electric motors with winding switching can be used with good efficiency and that on the other hand, the inevitable drop in efficiency in the stepless control in the one or the other switching stage is kept within limits, since not over the entire possible speed range from / 2 / to / 21 or / 20 must be regulated.

In this case, you can easily rely on the relatively cheap phase control for use the stepless speed control, since the loss of efficiency of the drive increases with decreasing Keep the speed within limits, provided that the speed ranges to be regulated are designed accordingly, d. This means that these speed ranges should not be chosen to be excessively large.

The working speed n _x can, if you z. B. is based on a fixed predetermined speed 222, can be adjusted manually and / or automatically by reducing the speed in the direction of 221 until you come to the working speed. The speed that is selected from the fixed preset speeds as the starting value for the stepless control, and the amount of speed reduction in the direction of the next lower fixed preset speed until it is reached

of n _x , are determined by the respective system conditions, operating parameters, external influences from weather and the like.

For example, the stepless speed control in a heating system can be determined by the outside air temperature, the flow temperature or the flow rate of the water in the heating circuit, the pressure conditions at the circulating pump and the like. If, for example, the outside air temperature falls or the flow rate is to increase, the control will regulate to a higher value for the working speed n _x and, if necessary, also switch to a higher of the fixed speeds, in order to then switch from this speed with the stepless setting of the working speed n _x to go out. Conversely, one could also assume a lower one of the fixed predetermined speeds, provided this z. B. appears appropriate due to an increase in the flow temperature or the pressure difference at the pump.

Finally, the control according to the invention can also be used to reduce flow noises in the heating system largely exclude. Such noises often arise when certain pressure differences prevail at certain speeds, for example on radiator valves or other control fittings and there the heating water will flow correspondingly quickly with the result that flow noises arise. It is understandable that with circulating pumps, the speed of which can only be changed in steps, accordingly has little leeway to find and set the speed, on the one hand none Flow noises occur and, on the other hand, the pump can still deliver the desired performance. Such an optimal speed can, however, easily be found with a stepless control and adjust.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing described. It shows

F i g. 1 shows a longitudinal section through a circulation pump, FIG. 2 a diagram with pump characteristics for two fixed speed levels and a continuously adjustable working speed,

F i g. 3 is a block diagram for the stepless control of a circulation pump in a range between two fixed speeds,

F i g. 4 shows a diagram with pump characteristics for three specified speeds and

F i g. 5 a block diagram for the stepless control a circulation pump in several ranges between fixed predetermined speeds.

The in F i g. 1 is shown in terms of its basic structure and function well known. Such pumps are for example in the German Offenlegungsschrift 2516 575, 25 29 399 and 26 39 541 shown and described. Therefore, only some of the components of this pump are presented here are described, which are important in connection with the invention.

The windings 1 of the pump motor are connected with their ends to contacts that are fixed in a installed half or socket 2 of an electrical connector are next to other contacts, with which the ends of the conductors of the power cord 3 are connected.

The other half or the plug 4 of this plug connection is part of a control module 5 and has plug contacts which are arranged in a specific configuration to the contacts of the socket 2 and are connected to a bridge combination 6 belonging to the module 4 so that, depending on the in which position the plug 4 is plugged into the socket 2, the motor windings are switched and connected in different ways, for example in a star or delta connection. In this way, the speed is set in stages to the fixed speed values n \, Π2 ... n, - . The module 5 is therefore permanently pre-programmed to certain speed values through the arrangement of the contacts in the plug 4 in relation to the contacts of the socket 2 and through the wiring of the bridge combination 6, whereby the finally set speed then depends on the position in which the module 5 or whose plug 4 is pushed onto socket 2. A similar solution is known from German laid-open specification 27 00 116, to which reference is made here in order to avoid repetitions.

The control module 5 also includes the electronic control 7 for the stepless speed setting. As has already been mentioned, a phase control should expediently be used as control 7, which is matched to the characteristics of the pump motor. This control can be activated with a conventional setpoint generator or speed controller 8 for the manual or automatic setting of the working speed n _x . As an alternative to this, an external setpoint generator 9 can also be connected to the module 5 or the control 7 via a separate input.

The F i g. 2 shows two pump characteristics, namely the mutual dependence of the delivery head H and the delivery rate Q at the two speeds n \ and n% , the lower speed n \ ζ. B. for night or summer operation of the heating system comes into consideration. The associated circuit of the motor windings 1 via the plug connection 2, 4 and the bridge combination 6 is indicated in the upper part of FIG. The three winding pairs are in this case, for. B. executed as a Dahlander circuit.

The step-by-step changeover to the higher speed / 22 can be carried out as described by changing the position of the Module 5 done in such a way that the wiring of the bridge combination 6 and the controller 7 with the Speed controller 8 as shown below in FIG. 3 shown.

In this case, the pump runs at the higher speed / 22 and, as already mentioned, can proceed from this speed in the direction of the lower speed n \ and also in the opposite direction with the speed controller 8 to the working speed which is favorable for the particular case n _x can be adjusted. The possible way of stepless speed change is shown in FIG. 2 indicated with an arrow.

The control and circuit example shown in FIGS. 4 and 5 relates to a three-stage circulating pump with the three fixed speeds n 1, n ₂ and n ₃ . The diagram in FIG. 4 shows the associated characteristic curves and indicates the possible infinitely variable control ranges with the arrows drawn.

The fixed predetermined speeds n \, m and 723 can also be set in this case by appropriately plugging the module 5 onto the lower connector half 2 in order to drive the motor windings 1 as a function of the appropriately prepared

To be able to switch the wiring of the bridge combination 6 as shown for two speeds in FIG. At the lowest speed n \ is that in FIG. 5 delta connection of the motor windings 1 shown above is effective.

To set the next higher speed nt , module 5 must be repositioned accordingly. For the speed n ^ then the bridge combination 6 switches the supply lines to the motor windings 1 as shown in Fig. 5 below, where the dashed box 6 (n ₃ ) surrounds the relevant connections for this case. The motor windings are then connected in star. The switching examples for other fixed speeds tu ... n, - are not shown in Fig. 5. Such circuits are also generally known and therefore do not need to be explained in more detail. Regarding the relevant state of the art, reference is made to German Offenlegungsschrift No. 25 13 164.

If one assumes in the embodiment shown in FIGS. 4 and 5 that the speed n _{2 is set} by Dahlander connection of the motor windings 1, the speed in the direction of the speed n \ and can via the phase control 7 and the speed setpoint generator 9 vice versa, in order to arrive at the working speed n _x , the given control range being able to include all values between m and iti. In a corresponding manner, the speed can also be controlled in the range between the speeds / 73 and / 72 after the fixed speed / I3 has been set in advance. Finally, a stepless regulation from the speed n \ in the direction of the speed zero is also possible in a corresponding manner.

Even if one has to accept that with this type of regulation certain losses in connection with the Efficiency occur and such losses are greater, the further you are from one of the the given speed approaches the next lower speed, is the main advantage in spite of everything predominate that on the one hand you can regulate the entire speed range steplessly and on the other hand, you do not have to accept the high losses in efficiency, as you would if you did this entire speed range steplessly in one pass, for example with a phase control should regulate.

In addition, the solution according to the invention also provides the possibility of using other known Controls for speed controls to work that would otherwise not necessarily be suitable without essentials Control losses in efficiency of the circulation pump for the entire intended speed range.

For this purpose 2 sheets of drawings

Claims (3)

Patent claims: 1. Circulation pump for heating systems whose motor can be set to at least two specified speeds (n \, 222 ... 72 /) by changing the winding, of which the lowest speed (n \) is designed to operate the system in an economy level and each higher rotational speed (n ₂ ... / J) of another stage of operation of the system is associated, characterized in that the engine rotation speed, starting from one of the higher predetermined speeds (πι ... πί), continuously in the direction of the next lower speed (m · ■■ n, -1) can be adjusted to a working speed (n _x ) adapted to the respective system conditions. 2. Circulation pump according to claim 1, characterized in that the respective working speed (n _x ) can be adjusted either by hand and / or automatically depending on variable system conditions or control parameters, such as outside temperature, flow temperature, pressure conditions and flow rate. 3. Circulation pump according to claim 2, characterized in that the working speed (n _x ) is adjustable with a phase control (7,8) known per se.