PLANT WITH AT LEAST ONE HYDRAULIC PUMP

The invention concerns plants with at least one hydraulic pump, in particular water pump, preferably centrifugal pump, which is propelled by an electrical engine, and with an electrical printing limit value switch connected with the consumer net, that opens with exceeding of an upper limit value of the consumer printing and when falling below a lower limit value of the consumer printing schließ t.

With such plants the controllability of the Pumpenleistung is used by variation of the pump drive number of revolutions usually to cover varying values consumed with constant pressure or according to given criteria sliding pressures. In addition, likewise the pumping plant delivery can be kept constant with supply pressures at will varying or be led, e.g. with filtering units with variable filter resistance, according to certain criteria.

The necessary number of revolutions of the pumps becomes usually by means of p (proportional), PI (proportional integral) or PID (proportional integral differential) automatic controllers by comparison of a measured actual value of the consumer printing with a given desired value of the consumer printing determines and an appropriate signal (similar output signal) of the automatic controller the food equipment of the pump engine, e.g. a frequency changer with Drehstromkurzschluß anchor engines or a Thyristerstromrichter with direct current motors or a tension controller supplied.

A well-known plant of the before-described kind becomes on the basis the Fig. 1 and 2 for example described. Fig shows. 1 schematically two variants of such a plant, Fig. 2 a printing time diagram for this. Gemäß Fig. 1 becomes the pump 1, in this case a centrifugal pump, by the electric motor 2, here a Drehstromkurzschluß anchor engine or a direct current motor, propelled. The engine 2 the automatic controller 3, a number of revolutions controller or other food equipment, e.g. a frequency changer affects with Drehstromkurzschluß anchor engines or a Thyristerstromrichter with direct current motors or a tension controller. This automatic controller 3 receives the above-mentioned signal of a proportional plus reset controller 4, which determines this signal due to the comparison of the values of the printing actual value giver 5 and the printing desired value giver 6. With V the consumers are attached. As broken suggested, still another memory boiler can be attached 8 to the consumer net N. The diagram gemäß Fig. the function of this well-known regulation and/or plant in the enterprise illustrates 2, whereby along the abscissa the time Z and along the ordinate the pressure D are laid on. St is lä&szlig the point of starting time, H; t the run-up period recognize and railways refer to continuous operation. The line DS indicates the printing desired value. The broken line FD indicates the supply pressure of the pump and/or its process or development in the enterprise of this plant, whereby this supply pressure resembles the pressure in the supply network N and represents a function of the number of revolutions of the engine.

This regulation causes continuous continuous operation of the pump with values consumed from 0 to 100%. At very small values consumed and with a quantity consumed 0 the pump of this well-known plant particularly works then uneconomically. It runs e.g. with consumption 0 only, in order to hold the pressure, without promoting however. That leads to an unwanted heating up of the pump and to an unnecessary energy consumption.

Beyond that the employment one is necessary the aforementioned p, PI or PID automatic controller with establishment of such a plant, which particularly represents a substantial share of the cost with small Anlaqen.

In the DE-A-37 20,360 a procedure for the controlling of the operating point of pump engines is descriptive, with which cyclically aprupt between the rated speed and a number of revolutions scarcely over zero and one shifts. The Druckstö&szlig developing thereby; e are absorbed by a pressure balance container.

In WORLD PUMP (No. 315, December 1992, pages 32-35, “The Answer tons pump surge control”, P. Costello) is likewise a procedure for the controlling of the operating point of pump engines under employment of a characteristic diagram automatic controller descriptive.

The FR-A-2 608,332 shows an engine with put on frequency converter. The invention is the basis the task to thus save the use of this P to avoid PI or PID automatic controllers the costs of these devices and to prevent further the uneconomic enterprise of the pumps with against 0 going deliveries.

This task becomes erfindungsgemäß thus solved, daß between the exit of the printing limit value switch and the driving motor (2) a number of revolutions controller, in particular frequency changer with build-up and low run ramp, it is inserted with which with closed limit value switch by the number of revolutions controller the engine speed and thus the delivery up to reaching the upper printing limit value (A) is gradually riserable and with open limit value switch by the number of revolutions controller the engine speed and thus the delivery up to reaching the lower printing limit value is gradually up to the engine stop reducable. One does thus without the use of p, Pl or PID automatic controllers. Thus the number of revolutions controller not by, in particular similar, od.dgl. a such well-known automatic controller, is headed for output signal but by the tax contact of a nomalen pressure control valve of point of two and/or printing limit value switch switched on and/or off.

With the engine food equipment connected the number of revolutions controller, e.g. a frequency changer, is started by this tax contact when falling below the lower printing limit value in the supply network and increases the number of revolutions of the pump continuously gemäß its build-up ramp to by which rising mechanical handling capacity of the pump the upper printing limit value (point of switching off) in the supply network is reached. Now the tax contact of the automatic controller and the engine food equipment open receive the switching off instruction and decrease the number of revolutions of the pump again continuously according to its gravity incline. This happens until thereby the pressure in the plant and/or in the supply network drops again up to the lower adjusted limit value and again starts the engine food equipment. This descriptive procedure repeats itself continuously.

The use of printing limit value switches in connection with the electric drive of hydraulic pumps is actually well-known. Hiebei is switched off directly however contrary to the invention not the number of revolutions controller, but the pump drive engine.

Such a before-well-known plant becomes on the basis the Fig. describes 3 and 4, whereby the Fig. 3 schematically the plant, the Fig. 4 an associated time quantity diagram illustrates.

The mechanical handling capacity of the pumping plant becomes here angepa&szlig thereby varying values consumed; t, daß the pump 1 in the intermittent enterprise works. In addition is necessarily, daß at the consumer net N a memory boiler 8, i.e. a printing air chamber with sufficient volume attached is. This boiler is to the Groß part with air or gas filled and can during the run of the pump 1 that part of the pump delivery take up, which momentarily one does not use. Thus air in the boiler 8 is compressed and the pressure rises. As soon as in the boiler the given maximum pressure, i.e. the switch-off pressure are reached, the driving motor becomes 2 and thus the pump by at the boiler or at the Verbraucherleitung and/or to the consumer net N, on which the consumers V hang, attached pressure control valve of point of two and/or push button switch 7 switched off.

Since therefore the promotion of the pump 1 stops immediately, the water is pressed by compressed air the boiler 8 into the Verbraucherleitung and/or into the net N, in order to cover continuing consumption. Thus the pressure in the boiler 8. sinks with reaching the preselected minimum pressure, i.e. the starting pressure, the pump is restarted. It supplies immediately again its full delivery, those again partially to the Verbraucherleitung and partially to the boiler fließ t. The before-descriptive procedure repeats itself continuously. This illustrates in particular the diagram in Fig. to 4, into along the abscissa the time t, along the ordinate the delivery of the pump Q one laid on. The upper horizontal line I shows the pump delivery at full number of revolutions (100%), those far line down present II a momentary quantity consumed. The upper hatched fields A illustrate in each case the quantity taken up by the boiler 8 with pump run, in other direction the hatched fields B the quantity delivered by the boiler 8 with the pump stop. With “” and “out” still the times of switching on and off are suggested the pump.

This before-well-known control type has the following disadvantages:

1. 1. The volume of the pressure vessel 8 muß relatively groß its, in order to limit the switching frequency of the pump 1 and/or their driving motor 2.
2. 2. A strong mechanical load of the pump 1 and the driving motor 2 arises as a result of continuous and/or repetitive starting on full number of revolutions and again stopping of the machine.
3. 3. Auß continuing varying of the pressure in the Verbraucherleitung between out and starting pressure, whereby the difference between these two pressures amounts to approx. 20 to 25% of the switch-off pressure, results to erdem there otherwise the switching frequency of the pump 1 groß would be mü&szlig and/or; Te.
4. 4. In the case of use out of the inlet-lateral pipeline R briefly and suddenly with the approach of the pump 1 the full pump delivery is always taken from the pump 1 as pressure increasing system, although the quantity consumed is in the Verbraucherleitung N perhaps substantially smaller and more continuous. That means unwanted Druckstöß e in the inlet-lateral pipeline R, out of which the pump takes the water and/or the other liquid from 1.

With that erfindungsgemäß EN control is switched off and on in contrast to this - as mentioned - by the pressure control valve of point of two not the pump drive engine, but a number of revolutions controller, which increases the number of revolutions of the engine when switching on on slowly and when switching this number of revolutions off again slowly reduced. With the number of revolutions of the pump also the delivery of the pump is varied. By the relatively slow change of the pumping deer number and thus the pump delivery when switching on and off the delivery of the pump varies not suddenly between 0 and 100% as with the well-known control type, but only in substantially smaller Ausmaß. Thereby the storage volume of the pressure vessel can be substantially reduced or with sufficiently groß em completely escape supply network. The difference between in and switch-off pressure can auß erdem to be kept very small, e.g. with approx. 3 5% of the pressure in the Verbraucherleitung, particularly since on use of an electronic pressure control valve of point of two the switching frequency can be very high, without daß the pump, the engine, the controller or the pressure control valve of point of two to be inadmissibly stressed.

An arrangement of the invention is characterized, da&szlig by it; on use of electronic pressure control valves of point of two and/or electronic threshold value - switches between the consumer net N and the electronic pressure control valve of point of two and/or the electronic threshold switch 7 a Meß transformer 9 for transforming the pressure into an electrical Größ e, for example electric current or tension are inserted. Such Meß transformers are low-priced and from many offerers in the trade available, whereby different standardized electrical output signals are available, e.g. the so-called 20 machine-CCIT-place with a current range from 4 to 20 mA or tension exits with 0-10 V and/or -10 to +10 V. are alternatively available also, e.g. over opto coupler, electrically isolated exits. The Meß transformer is arranged directly in the consumer net and galvanically, e.g. by means of two-wire line, or galvanically separately, e.g. by means of opto couplers, with the electronic pressure control valve of point of two and/or the electronic threshold switch connected. By inserting the Meß transformer can be arranged the electronic threshold switch and/or pressure control valve of point of two spatially separately from the consumer net. Like that it is for example possible to accommodate the threshold switch together with the number of revolutions controller in a housing which also squirting or radiationwater resistantly can be implemented.

Gemäß the further arrangement of the invention a separate number of revolutions controller is intended with presence of two or more pumps for each individual pump, which stands with the consumer net over a separate pressure control valve of point of two and/or printing limit value switch in connection.

For the spatial accommodation of the plant and for an economic enterprise it can be favorable, if gemäß the invention the number of revolutions controller directly to, in particular on that, driving motor of the pump is installed, whereby preferably the cooling air flow of the engine serves also the cooling of the number of revolutions controller.

It is zweckmäß industrial union, daß the number of revolutions controller and in particular the pressure control valve of point of two and/or the threshold switch are built into a housing and/or are da&szlig, which preferably consists of a radiator box and a housing cap, and; this housing, preferably this radiator box, in the cooling air flow of the engine is arranged. Since in the case of rising engine speed on the one hand the power demand of the pump, which power input of the engine rises and thus the waste heat production of the controller result and on the other hand itself also the intensity of the cooling air flow of the engine exhaust increased, a cooling meeting demand of the controller.

It, if the radiator box of the housing for the number of revolutions controller exhibits cooling fins, is particularly favourable by which with the enterprise of the plant the cooling air flow of the engine is through-steered. Thus the cooling efficiency of the radiator box multiplies and au&szlig opposite a cooling plate; the cooling fins form channels for the air flow for erdem, whereby the air flow can be steered purposefully by the cooling fins through on the engine exhaust. But it is zweckmäß industrial union, daß the radiator box of the housing for the number of revolutions controller is directly over an exhaust wheel connected with the pump motor drive wave arranged. Apart from the compact building method and the descriptive flowtechnical characteristics thereby also the electrical behavior of the controller is effectively improved. Modern controllers (frequency changers) work at the production of the three-phase alternating current for the engine supply with relatively high switching frequencies (to approx. 14 kHz). In the case of separate arrangement of frequency changer and pump long cable connections between these devices result, whereby it often comes to unwanted interferences by the antenna effect of these cables. This negative effect is avoided to a large extent by the direct structure of the frequency changer on the engine, since the cable connection length is reduced thereby by some meters to few centimeters. The supply of the pump including driving motor and controller as a compact, in itself verkabelte ready for use unit decreases auß erdem substantially the installation costs, among other things through escape a scolding and a rule cabinet with cooling blower for the controller.

Zweckmäß igerweise is at least sprayingwater resistant the housing for the number of revolutions controller in the assembled condition. This makes the employment of the unit pump - for controller possible in humid rooms.

Further it is, if the service section with high dissipated heat of the number of revolutions controller is located on the radiator box directly and beabstandeten those, only small dissipated heat delivering, control electronics on at least one, of the radiator box, plate in the housing is favorably arranged. By the mounting of the service section directly at the radiator box thermally at most stressed components are cooled such as power transistors the etc. optimally by the radiator box the flowing against cool air. The heat sensitive construction units of control electronics, which exhibit even only small energy dissipation, can be accommodated thereby the service section beabstandet. By laminating several plates one keeps one gro&szlig one above the other; e plate total area, on which complex circuits, input/expenditure circuits e.g. microprocessor-supported can be planned.

The invention becomes in the following on the basis the Fig. 5-13 for example describes. Fig. 5 and 5 ' shows two variants of one erfindungsgemäß EN plant, the Fig. 6 an associated printing time diagram and the Fig. 7 a quantity time diagram in addition. In Fig. 5 and 5 ' is designated above appropriate parts with the same reference symbols as. The memory boiler 8 planned only as required after above remarks is demgemäß broken suggested and is in the given case smaller in the volume held than the memory boiler gemäß the well-known training after Fig. 3. The Fig. 8 and 9 shows further arrangements of the invention in side view, the Fig. 10 and 11 around 90° against each other rotated profiles by one erfindungsgemäß e plant and the Fig. 12 and 13 perspective opinions of pump plants, with which the regulation housing is put on on the pump engine directly.

As already mentions above, becomes erfindungsgemä&szlig with that; EN plant by the pressure control valve of point of two and/or push button switch of point of two 7 the number of revolutions controller 3 switched on and off. The automatic controller and/or switch 7 verläß t in well-known kind its switching contact respective with delay and/or its respective switching final position, in order to take however after such opening abruptly its other switching final position. The number of revolutions controller 3 increases the number of revolutions of the electric motor 2 when switching on on, here a Drehstromkurzschluß anchor engine or a direct current motor, slowly and reduces those when switching the number of revolutions controller 3 off again slowly. With the number of revolutions of the engine 2 and thus with the number of revolutions of that propelled pump 1 also the delivery Q (Fig becomes. 7) varied. In the diagram after Fig. again the time Z and/or t is, made for 7 along the Y-axis the delivery Q of the pump evidently along the x-axis. With 100% the pump delivery is suggested at full number of revolutions, with the line mV the momentary quantity consumed, with the line the mVe delivery of the pump and/or the quantity consumed when switching on on (“” - positions), with the line mVa when switching off (“out” - positions). The associated printing time diagram läß t Fig. 6 recognize, whereby along the abscissa again the time Z and/or t is laid on u.zw the starting time St and the stop time FR of the pump is evidently made and along the ordinate the pressure D, i.e. the supply pressure of the pump and/or the pressure in the consumer net. The line e (lower limit value) makes points of switch-on time, the line A (upper limit value) evident points of fall time. The consumption end is suggested with E. The broken line GL makes the respective supply pressure of the pump 1 visible as function of the number of revolutions, the dotted line PL the pressure in the supply network N.

A further characteristic of the invention consists of it, daß , as above did not describe, intend for the regulation of the pump 1 fixed or sliding desired value of the supply pressure of the pump (DS in Fig. 2) one gives, but an upper limit value A and a lower limit value b. leads to it, daß the pump 1, as soon as consumption goes against 0 remains to hold being located and does not keep running in the uneconomic enterprise, only in order the pressure. Stopping the pump takes place erfindungsgemäß , because after opening the automatic controller contact with the higher limit value, as soon as no consumption is present, this higher pressure remains existing in the net N and the pump drive engine 2 due to the opened automatic controller contact gemäß the gravity incline A (Fig. 6!) the number of revolutions controller 3 in his number of revolutions up to the stop one reduces. This concerns an essentially closed reticulated system; it can be regarded with losses from 1 to 2% still as closed. Only with using a recent consumption the system pressure (pressure in the net N) sinks again off and the pump 1 is recently started with reaching the lower printing limit value A.

Further training of the invention consists of it, daß the instruction for start and stop (high rules and Abregeln) of the number of revolutions controller 3 not by means of a mechanical pressure control valve, but by one or more electronic threshold switches is given. These electronic switches do not have mechanically moved parts and to be subject thus no Verschleiß. They make effected via it a high switching frequency, there also the subsequent treatment of the control instructions in the controller 3 purely electronically and thus likewise for no Verschlei&szlig possible; is subject. By relatively short times for the high and Abregelvorgang of the number of revolutions controller 3 the high switching frequency mentioned will become reached and thus again inadmissible printing break-downs when restarting the once stopped pump 1 by an using consumption avoided. Fig. ' such an arrangement of the plant with electronic threshold switch shows 5. Is between the consumer net N and the electronic threshold switch 7 a Meß transformer 9 for transforming the pressure into an electrical Größ e inserted. Can each commercial pressure/current or pressure/tension Meß transformer to be used. In industrial plants Me&szlig are particularly favourably applicable; transformer with electrically isolated exits. By an electrically isolated connection, over opto coupler or the like, the Meß transformer with the threshold switch caused mass stream, which can lead to the falsification of the regulation, can be avoided by potential shifts.

With application that erfindungsgemäß EN control becomes zweckmäß igerweise with plants with several pumps each machine a controller (frequency changer) assigned. Gemäß the Fig. 8 and 9 this controller can be installed directly at and/or on the pump drive engine in a further arrangement of the invention. An obligatory cooling air guidance in the controller can be obtained by this building method by the engine exhaust wheel. In the following now Ausführunqen of the invention are described, with which the number of revolutions controller is put on on the pump engine built into a housing provided with radiator box and this housing directly.

Into the Fig. 10 and 11 is to be seen right-angled to each other led cuts by the housing of the number of revolutions controller. This housing consists of a radiator box 13, on which directly the service section 3 is appropriate ''' the controller. For the better thermal conduction between service section and radiator box a thermal compound laid on between them serves. This side of the radiator box is locked by a cap 14, whereby the connection between radiator boxes and cap is implemented generally. The housing cap 14 takes up further plates 3 ', 3 '' with control electronics of the number of revolutions controller (frequency changer). On that the engine exhaust 12 turned side of the radiator box cooling fins are intended, anschlie&szlig to the one further part of 15 of the automatic controller housing; t, which is intended for positive connection, for example by plug-on, with the engine 2. In the enterprise the exhaust wheel 12 sucks in by the flow channels fresh air formed by the cooling fins and blows it over and by the engine, whereby also the radiator box is cooled at the same time. The steering of the air flow takes place gemäß the arrows 10.

The figures 12 and 13 show in the perspective units, consisting of a single-step (Fig. 13) and/or multi-level (Fig. 12) Pump 1.1 ', which is propelled by an engine 2, on into a housing, consisting of a cap 14, a radiator box 13 and one attach-hurry 15, inserted number of revolutions controller 3 (frequency changer) is directly put on. The output cables 16 of the frequency changer are direct to the Anschluß box 17 of the engine led, so daß one with a cable length of few centimeters the sufficiency finds. In Fig. 13 is further a Meß to see transformer 9, which forms the pressure control valve of point of two together with an electronic threshold switch.