EP2357363A1 - Operational management device for a positive displacement pump, pump system and method of operating such - Google Patents

Abstract

The operation controlling device comprises a pump motor with an actuation unit (12), particularly for setting the rotational speed for the pump motor, and a state sensor unit (20) for detecting an actual operating parameter, particularly operating pressure of the positive-displacement pump (14). An operating mode unit (18) is provided, which is configured, such that an actuating mode for the pump motor is set by the actuating unit below an operating-parameter threshold value. The operating-parameter threshold value is fixed or is calculated as a value or a pump parameter which is correlated.

Description

The present invention relates to an operation control apparatus according to the preamble of the main claim, further to a pump system and a method for operating a pump system.

Against the technical background of applying machine tools with coolants and / or lubricants at operating pressures which can reach 25 bar and more, the pumps used are of particular importance. In particular, in connection with industrial drilling, milling or tapping processes and a fluid loading in the order of magnitude mentioned so high cooling capacity and correspondingly high process speed can be realized.

For the high-pressure coolant supply displacement pumps have prevailed as in machine tool construction, since they can realize a possible fluid pressure, which can reach 80bar, with a single, compact unit and thus have advantages in the high-pressure sector compared to otherwise conventional centrifugal pumps.

In particular, a (three-spindle) screw pump has proven and enforced as a positive displacement pump, due to its low-pulsation and uniform conveying characteristics, combined with high wear resistance.

However, by design, screw pumps (as well as other positive displacement pumps) in a system with associated equipment (eg, the machine tool) require a pressure control valve to maintain a (predetermined) pump pressure constant. The pumps are operated at a constant speed and provide an approximately constant flow rate due to their displacement characteristics. One each in a machine tool used tool requires at the predetermined pressure a fluid flow rate, which is usually below the amount provided by the pump; Accordingly, the excess flow rate (differential flow rate) is derived via the pressure control valve, whereby the efficiency of the system compared to the (in principle possible) high efficiency of the positive displacement pump is reduced, since the necessary for the pressure build-up in the differential flow pump capacity is not used.

During work breaks (eg for tool change or the like), no cooling lubricant may be pumped to the machine tool. For this purpose, either a shut-off valve is installed in the supply line to the machine tool, or the pump is switched off; However, due to the high mechanical load switching off is usually only in systems in question, which operate at relatively low pressure. In systems with a shut-off valve, the pump will continue to operate (with the shut-off valve closed) at full power via the pressure regulator, with consequent detrimental effects on efficiency. In order to reduce the power requirement in breaks during this procedure, a controllable pressure control valve is often used, which can be depressurized in the working cycles.

Also known is the use of pressure control valves with variable pressure. These have the advantage that the fluid supply can be suitably adapted to the requirements of the process, whereby, for tools with low pressure requirements, the power consumption of the positive displacement pump then decreases with the pressure. However, even with this controlled-valve approach, the power consumption of the pump is usually higher than the actual power requirement for the fluid supply to the tool, since a higher flow rate is provided than required. Since coolant supply and cooling typically take up to 35% of the energy consumption of a machine tool, the potential for improvement or optimization is considerable.

Another disadvantage of valves used for pressure control is that, for example, in systems for coolant supply of machine tools, the switching of the valves leads to pressure pulsations, which load the system heavily, possibly even causing mechanical damage.

As a further approach to be proposed as known, the variation of the rotational speed of the pump motor by means of a frequency converter is known. It is intended to return the pressure in the system after the pump via a pressure sensor as a control variable to the frequency converter and impart the pump motor speed as a control variable by means of a PI control (via the inverter) on the pump motor.

However, such a control using a classical control method has the disadvantage of insufficient dynamic behavior; In particular, it is not possible to realize a rapid startup of the pump motor to its desired speed or the target pressure without adverse overshoot. In contrast, a more damped increase leads to comparatively long start-up and thus dead times, which in turn od disadvantageous in unproductive operating side lives of a particular machine tool. Like. Reflected. In particular, it has proven to be desirable to achieve a setpoint value, starting from a switch-on, in no more than 500 ms, which is unachievable in practice, for example, with known control algorithms in the present context of the operational control of a spindle pump.

Finally, it is to be assumed as from the prior art that combinations of the above-described approaches are carried out, ie a regulation of the pump motor with pump pressure takes place as a control variable and additionally the pump cooperates with a downstream valve of the type described above. Accordingly, such a technology also has the identified disadvantages of high equipment complexity and poor dynamics.

The object of the present invention is therefore to provide an operating control device for a positive displacement pump having a pump motor, which after activating the target variables, such as a target pressure and / or a target speed in the shortest possible time and without over or undershoot effects in Control process achieved. In this case, high equipment costs, in particular additional effort through shut-off and / or pressure control valves to avoid. Thus, it is also an object of the invention to provide an operation control device which can be used flexibly, in particular for different operating parameter target values is suitable (ie about different target pressures for suitably used tools), the power consumption in the interest of optimizing the energetic Efficiency is to be reduced and adverse pressure pulsations in the system are to be avoided.

The object is achieved by the operation control device having the features of the main claim, furthermore the pump system according to independent claim 12 and the operating method according to claim 18; advantageous developments of the invention are described in the subclaims.

In an advantageous manner according to the invention, the drive means according to the invention (ie the otherwise known frequency converter for the pump motor) are assigned operating mode means so that they can specify a plurality of operating modes (outside a switch-off state).

In departure from a traditional control operation, such as with the dilemma to be solved between overshoot at high power-up and adverse slow-down time delay, the inventive approach allows in the first drive mode and in response to the detected operating parameter change in the predetermined time interval, adaptive and dependent on the with minimal rise time to increase the pump pressure (operating pressure, as a typical implementation of the operating parameter) and then according to the invention upon reaching or exceeding the first operating parameter threshold (ie, about a pressure or Drehzahlschwellwerts) switch to the second control mode, which, to approximate the operating parameter target value (ie, about the desired pressure or a target speed) a less steep and thus overshooting allows avoidance of operation; Subsequently, the setpoint value would then also be adjusted in otherwise known manner in stationary operation in this second operating mode.

According to the invention, the first operating parameter threshold value is defined as a predetermined fraction of the operating parameter target value or is calculated according to the invention, whereby this fraction according to preferred embodiments of the invention in the range between 90% and 98% of the desired value, in particular in the range between 94% and 96% of the target value, moves. Alternatively, it is also possible to calculate a threshold value of a pump parameter derived from the operating parameter setpoint.

In this way, a very dynamic, i. E. allow a short start-up or startup, pump operation, which is the conditions of use in about the fluid supply of machine tools in a fair manner (without necessarily being limited to machine tool technology within the scope of the invention).

In a preferred embodiment of the invention, it is provided that the operating mode means additionally use a second operating parameter threshold value (that is to say pressure threshold value) which lies below the first operating parameter threshold value and triggers the detection of the parameter change (relative to the time unit) according to the invention; This inventive aspect is based on the inventive finding that favorable detection conditions do not already exist immediately after activating or switching on, but rather only after reaching a threshold (determined by the second operating parameter threshold), for example a pressure threshold, which according to preferred developments the invention in the range between about 15% and 25%, preferably 20%, for example, based on the operating parameter target value.

In this case, it is on the one hand encompassed by the invention to derive suitable parameters for the rise behavior of the pump pressure during the first activation mode in response to a detection of the operating parameter only once (in practical implementation, for example, from the operating parameter change a gain factor for a PI control behavior However, during the first activation mode, it is alternatively and preferably possible to record the operating parameter change per time interval (ie its slope in the time diagram) repeatedly and / or continuously during the first activation mode and then the (control) behavior during the first activation mode To adapt to control mode.

In addition, it is advantageous within the scope of a further development of the invention to carry out a full-load starting operation until the second operating parameter threshold value is reached, ie. to provide a start of the pump motor with maximum drive power. On the one hand, this results in the advantage of minimized time expenditure in this early activation phase without the risk of disadvantageous overshooting; on the other hand, defined conditions are present at the end of this early start-up phase for determining the parameter change according to the invention, in order to influence the further control curve during the first activation mode.

In the context of the invention, it has proved to be favorable and pragmatic, the control behavior in the first and in the second operating mode by a control behavior, such as a PI control behavior to map, while providing a demarcation between the Ansteuermodi, such as by changing the control gain factor.

In the context of a preferred realization of the invention, it is to regard the operating pressure (pump pressure) as the operating parameter and then the operation control in the direction of a desired pressure of the pump (for a respective Use case, so about depending on a specific tool used) perform. Both the first threshold value and the second threshold value are then present with this setpoint pressure as the pressure threshold value. Accordingly, the state sensor means are realized by means of a pressure sensor which detects and provides this operating pressure (preferably continuously).

Alternatively, it is nevertheless possible within the scope of the invention to measure the operating pressure as an operating parameter not directly by means of a sensor, but to determine it from other system and pump parameters (in otherwise known manner) which are present within the pump system, in particular using the (Pump) motor voltage, the motor current, the motor speed, a motor rotational acceleration or other (about constant) pump parameters of a respective positive displacement pump used which are suitable for operating pressure determination and charged in an otherwise known manner for pressure determination.

Within the scope of preferred developments of the invention, it is also appropriate to use other variables as operating parameters as an alternative to the operating pressure, for example a (current) delivery rate of the positive-displacement pump or an engine speed of the pump motor. Also, the operating parameter setpoint and the at least one threshold need not necessarily be the same size (e.g., pressure).

Particularly suitable and within the scope of the invention, the operation control device is used in a pump system, which assigns the operation control device, a positive displacement pump and an impinged by the positive displacement pump with fluid unit; preferred and advantageous in the context of the invention is the positive displacement pump (more preferably dreispindelige) screw pump, the aggregate a machine tool, which further preferably with an operating pressure above 20bar, even more preferably above 40bar, and still more preferably above 60bar with cooling lubricant is acted upon by the positive displacement pump. It is particularly favorable and advantageous to operate the screw pump in the manner of a universal pump at high speeds, since in this way comparatively small and inexpensive pumps can be used. Accordingly, it is provided within the scope of preferred developments of the invention to provide positive displacement pumps, in particular screw pumps, which are operated at operating speeds above 3000 / min., More preferably above 4000 / min., Within the pump system.

According to the invention advantageously allows a system so constructed, the operating parameter target value, such as the target pressure to reach in less than 500ms and thus represents a significant advance over procedures according to the prior art. As moreover, according to favorable implementation forms The present invention can be dispensed with valves for pressure control of the pump, the present invention not only advantageous to avoid additional mechanical and aggregate effort, also exists about the above-described, adverse pulsation by the valve switching operations not even.

As a result, therefore, the present invention makes it possible to solve, in a surprisingly simple and elegant manner, the problem of dynamic performance arising from the prior art, ie, quickly achieving an operating parameter setpoint without overshoot, without requiring additional mechanical effort by valves or the like . becomes necessary. Thus, by the present invention, the prerequisite for a high degree of flexibility and adaptability to different operating conditions, such as different tools to be operated in a machine tool, each with different pressure conditions, created without complex adjustment, (pre-) Configuring or the like. Measures necessary In addition to the described optimization in operation, significant increases in efficiency can also be achieved in furnishing and retrofitting processes. The present invention is particularly suitable in the described manner for the application of high-pressure pumps for fluid supply for machine tools in industrial environments, but is not limited to this application. Rather, the present invention provides the advantages described in all technical applications, which need adaptive, flexible control behavior of pumps, especially in the high pressure area.

Fig. 1

ein schematisches Schaubild eines Pumpensystems mit Betriebssteuerungsvorrichtung zur Realisierung eines bevorzugten Ausführungsbeispiels der vorliegenden Erfindung;

Fig. 2

ein Druck-/Zeitdiagramm zum Verdeutlichen des Betriebsverhaltens der Vorrichtung gemäß Fig. 1;

Fig. 3

ein Betriebsablaufdiagramm als Flussdiagramm zum Verdeutlichen eines erfindungsgemäßen Betriebsablaufs;

Fig. 4

ein Druck-/Zeitdiagramm analog Fig. 2 zum Verdeutlichen des Betriebsverhaltens konventioneller Vorrichtungen bei variierten Betriebserfordernissen (z.B. unterschiedlicher Förderstrombedarf bei jeweils unterschiedlichen Werkzeugen im nachgeschalteten Aggregat).

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in:

Fig. 1

a schematic diagram of a pump system with operation control device for implementing a preferred embodiment of the present invention;

Fig. 2

a pressure / time diagram to illustrate the performance of the device according to Fig. 1 ;

Fig. 3

an operational flowchart as a flow chart to illustrate an operation of the invention;

Fig. 4

a pressure / time diagram analog Fig. 2 to illustrate the performance of conventional devices with varying operating requirements (eg different flow requirements for each different tools in the downstream unit).

The Fig. 1 illustrates in the form of a schematic block diagram the operation control device according to a preferred embodiment of the invention in the context of a pump system. More specifically, the block diagram illustrates the Fig. 1 characterized by the dashed border line 10, an operation control device with drive means 12, typically realized as otherwise known frequency converter, for speed adjustment and control of a downstream screw pump 14, which in the context of in the Fig. 1 shown system for conveying cooling fluid with a schematically shown machine tool 16 (typical example drilling or milling machine with exchangeable tool inserts and correspondingly variable flow rate requirement for a respective tool) cooperates.

In the context of the preferred embodiment shown, the drive means 12 are preceded by operating mode means 18 in the form of a control unit (typically realized from hardware or software components) which in the context of the invention in its control behavior with respect to the drive means 12 both calculated or predetermined threshold values 24 of an operating parameter (in the present Fall the pump pressure P) flow, as well as a respective aggregate-specific setpoint 22 of the operating parameter (here: set pressure P soll) into account. In the in Fig. 1 shown schematically, these influencing factors, namely at least one threshold value and the desired value P set, by means of functional units 22, 24 suitably provided (or as explained below, calculated).

It is also shown how a state sensor unit 20, in the exemplary embodiment shown a pressure sensor, on the output side of the spindle pump 14 detects an actual pressure "P ist" and sends it to the operating mode means 18 for consideration in the context of the further control.

With reference to the pressure / time diagram of Fig. 2 and the flowchart of the Fig. 3 to continue in the operation of the device according to Fig. 1 be clarified.

It is assumed by way of example that a screw spindle pump of the type EMTEC 20 R38 of the Applicant Allweiler AG, Radolfzell, a power of 7.5 kW with a single-spindle machine tool 16 cooperates, which is designed as a drill and a total of three different drilling tools is operated. Each of these three drilling tools requires a different flow rate of a coolant / lubricant fluid to be delivered by the pump 14, it being assumed that this flow rate is between 5 l / min. and 35l / min. lies. An assumed operating pressure on the pump output or aggregate input side is assumed to be 80 bar.

The Fig. 2 schematically shows an idle state in step S10 before activating the arrangement. By manual or automated control then follows in step S12, the commissioning Go.

Like the juxtaposition of Fig. 2 and 3 clarifies, the present invention allows by suitable control or setting by the operating mode means 18 operating the pump motor in several clearly separated or distinct operating phases. Thus, first according to the described embodiment of the Fig. 1 to 3 provided that starting from the step of commissioning at a time t _{o is} a driving of the spindle pump by means of the frequency converter 12 with maximum electrical drive power. This follows directly from the in Fig. 3 shown decision step E1, because the tested here differential pressure P diff (as the difference between the form "P soll" and the detected actual pressure "P is", based on the target pressure, here 80bar) is more than 80% below the Betriebsparameter- Set point (P set). Quantitatively, this means realizing a lower threshold, in the exemplary embodiment at the 80% threshold (based on 80 bar P soll, ie P2 = 16 bar). Accordingly, the branching leads into Fig. 3 to the operating state of step S14 "Start", corresponding to an initial start-up mode, here at full electric power.

As the Fig. 2 can be seen reached at time t _1, the pump actual pressure "P is" the lower threshold P2 at 16 bar; in the illustrated embodiment, this is the case after about 80msec. This completes the first phase, and the mode-of-operation means applies a different drive mode to the pump motor and the upstream inverter, respectively. Specifically, this results the flow chart of the Fig. 3 : If the lower threshold P2 of 16bar is exceeded (corresponding to a pressure difference of less than 80% with respect to the pressure set point), a branch to the right takes place in decision step E2. According to the preferred embodiment, a parameterization of a control operation in the second operating phase between times t ₁ and t ₂ in is thus carried out in step S16 Fig. 2 (corresponding to a pressure range of 16 bar as the lower threshold and 76bar as the upper threshold, corresponding to 95% of P soll). Specifically, a PI control operation is carried out here, wherein, after the time t ₁ , by the operating mode means 18 first a pressure difference per time interval as a slope of the pressure curve ( Fig. 2 ) is determined and dependent on this slope then the system determines and specifies a gain value and an integration time for the PI control behavior in the time period t ₁ and t ₂ , which then in step S18, the system continues to operate with this parameterization and described by a PI control function becomes. As well as by the feedback of the Fig. 3 In the time range between t ₁ and t _2, a continuous parameterization (S16) takes place, ie repeated measurement of a current slope of the pressure curve and then adjustment of P and I values of the control. In the concrete embodiment of the Fig. 2 For example, the curve shown there with a parameterization (S16) immediately after time t _{1 would} lead to a typical gain of 8 at integration time 5 msec (for example, compared to the maximum drive in phase t _o to t ₁ , where a drive with gain V = 1 and integration time I = 2msec).

In the in Fig. 2 As shown, then the pressure rise over time until reaching an upper threshold P1 at 76bar, this threshold is set to 95% of P soll. This threshold is reached at time t ₂ , in the illustrated embodiment at about 300msec with respect to t ₀ . At this time, in turn, the operational control behavior of the mode-of-operation means changes, wherein, according to a decided decision-making step E3 (FIG. Fig. 3 ), the system performs the so-called end control operation in step S20, namely a control operation, which typically compared to a control operation in the upstream operating phase has a reduced gain and / or extended integration time for the PI parameterization, in other words, from the upper threshold, a significantly flatter rise behavior towards the target value P soll shows. This then leads, according to the invention and advantageous, to a slower approach to the desired value P soll (80 bar) in the time interval between t ₂ and t ₃ , without an adverse overshoot occurring, for example. Rather, this executed in S20 Endregelbtrieb represents an operating condition with which the setpoint can be approached from below in optimized time from t ₂ , then in steady state operation with these control parameters (typically gain = 3, integration time 10msec) of the stationary pump operation is carried out.

In the event that - for example, by an unexpected load on the system, as it represents, for example, the shutdown or failure of a downstream machine tool - there may be operating conditions in which a current pump pressure exceeds the setpoint. In principle, it would be possible by the Endregelbetrieb (step S20) and this deviation (upward) to correct, but may require undesirably long time. Accordingly, as in Fig. 3 in this case, a typical example exceeding the desired pressure value by more than 5% (ie actual pressure> 105% of P), again in this case, is provided in the decision step E3 (option "no") steep parameterization of the operation of step S16 or S18, so according to the steep behavior between the periods t ₁ and t ₂ , to switch. As soon as the tolerance threshold (here: 5%) for the end control mode is reached, the operation continues accordingly.

In addition, the flowchart shows the Fig. 3 initiating an alarm routine (steps S22 and S24, respectively) if a predetermined alarm condition is detected in step E3; this can be a predetermined pressure behavior, but also switch off on other input variables (eg exceeding a critical temperature).

Especially in the comparison with the curves of the Fig. 4 thus illustrates the advantageous effect of the present invention with different Ansteuermodi and thus generated operating phases of the pump motor in startup and run-up state: Thus, the shows Fig. 4 the performance of a presumed as known operation control device with the same pump configuration, which is realized for example in the form of a PI controller, for the various tools and the associated different system loads. While, for example, for the first boring tool according to curve 40, a small required flow rate (5 l / min) leads to a significant overshooting of the system, a high flow rate requirement of a large tool according to curve 42 (flow rate 35 l / min) causes a very long entry time and exceeds that needed 500msec limit significantly. Only the middle tool according to curve 44 (flow rate 15l / min) reaches approximately the curve of the Fig. 2 with only a slight overshoot when reaching P soll, wherein advantageously and within the scope of the invention, the short curve of the Fig. 2 is achieved for all required tools, regardless of the respective funding needs, and is suitably adjusted adaptively, namely by each suitable, adaptive parameterization in the range of operating phases below the upper threshold, in particular in the medium rise range of the process step S18 between t ₁ and t ₂ (with a current operating situation adapted parameterization).

Thus, the present invention is not limited to the provision of two threshold values P2, P1 (namely, as shown in the embodiment, at 20% and 95% of the desired value), but it is within the scope of the invention possible to deviate one or both of these thresholds The invention also includes placing or selecting only one threshold value (preferably the upper threshold value P1) or any desired number of threshold values (possibly described by a continuous functional relationship) and the adaptively parameterized operation as described above up to this upper limit Threshold value according to a single or repeated slope measurement on the pressure curve suitable to adjust or adjust.

It is also within the scope of the present invention to provide other operating parameters, such as a rotational speed of the pump motor, differing from the pressure as an operating parameter selected here by way of example. Here, an upper and possibly lower threshold value may also be suitably preset, determined or set up as respective fractions other ways can be determined).

As a result, the present invention makes it possible to realize, in a surprisingly effective manner, a very fast and dynamic start-up behavior of a spindle pump, while at the same time minimizing the required apparatus and hardware expenditure; Namely works in accordance with preferred realization, approximately in Fig. 1 schematically shown system without a pressure control valve, which is connected downstream of the prior art devices of the spindle pump, so that the operation also takes place in an energy-efficient manner.

Claims (19)

Operation control device for a pump motor having a positive displacement pump (14), with
Means for controlling (12), in particular speed setting, for the pump motor,
Condition sensor means (20) for detecting a current operating parameter, in particular operating pressure, the positive displacement pump,
operating mode means (18) upstream of the drive means for specifying a mode of operation of the positive displacement pump,
characterized in that
the operating mode means are arranged such that, below a first operating parameter threshold value (P1), a first drive mode for the pump motor is set by the drive means, which causes a steadily increasing pump pressure in the direction of an operating parameter setpoint (P soll), variable, and in particular is in its slope behavior of the pump pressure dependent on a detected operating parameter change in a predetermined time interval,
and above the first operating parameter threshold by the driving means, setting a second driving mode different from the first driving mode to the operating parameter command value as a control operation,
wherein the first operating parameter threshold value (P1) is fixed or calculated as a fraction of the operating parameter setpoint value and / or a pump parameter correlated therewith. Apparatus according to claim 1, characterized in that the operating mode means are adapted to detect and determine the operating parameter change after reaching a second operating parameter threshold (P2),
wherein the second operating parameter threshold (P2) as a fraction of the operating parameter setpoint is lower than the first operating parameter threshold (P1). Apparatus according to claim 1 or 2, characterized in that the operating parameter change is detected and determined multiple times and each affects the first drive mode. Apparatus according to claim 2 or 3, characterized in that the operating mode means are formed so that below the second operating parameter threshold (P2), a drive of the pump motor by the drive means with maximum drive power and / or to achieve the fastest possible rise behavior. Device according to one of claims 1 to 4, characterized in that the operating mode means are formed so that the first drive mode has a control behavior, in particular PI control behavior, whose control gain greater than a control gain of particular a PI control behavior having control mode in the second control mode is. Device according to one of claims 1 to 5, characterized in that the condition sensor means comprise a pressure sensor (20) for preferably continuously detecting the operating pressure as an operating parameter. Device according to one of claims 1 to 5, characterized in that the condition sensor means for determining the operating pressure as operating parameters of pump and / or pump motor parameters are formed, consisting of a motor voltage, a motor current, an engine speed, a rotational acceleration and / or pump constants of the positive displacement pump are selected. Device according to one of claims 1 to 7, characterized in that the state sensor means for detecting a current flow rate of the positive displacement pump are designed as operating parameters. Device according to one of claims 1 to 8, characterized in that the fraction for the first operating parameter threshold (P1) in the range between 90% and 98%, in particular between 94% and 96% of the operating parameter setpoint (P setpoint). Device according to one of claims 2 to 9, characterized in that the preferably predetermined fraction for the second operating parameter threshold (P2) is in the range between 15% and 25%, in particular between 18% and 22%, of the operating parameter setpoint. Device according to one of claims 1 to 10, characterized by means for detecting a predetermined setpoint exceeding, which are arranged such that in response to exceeding the operating parameter setpoint by a predetermined tolerance value, the operating mode means set a different from the second operating mode drive mode for the pump motor, in particular activation mode with parameters, more preferably control parameters, of the first activation mode. Pump system with
a positive displacement pump, an output side of the positive displacement pump provided unit (16) and the operation control device (10) according to one of claims 1 to 10. Pump system according to claim 12, characterized in that the pump system has no pressure control valve for the positive displacement pump. Pump system according to claim 12 or 13, characterized in that the unit is a machine tool (16) which is acted upon by means of the positive displacement pump with coolant and / or lubricant fluid. Pump system according to one of claims 12 to 14, characterized in that the positive displacement pump is designed as a screw pump. Pump system according to one of claims 12 to 15, characterized in that the positive displacement pump for an operating speed above 3000 / min., Preferably above 4000 / min., Is set up and operated. A pump system according to any one of claims 12 to 16, characterized in that the operation mode means of the operation control device sets the first drive mode so that the operating parameter set value is reached in 500ms or less after the pump motor is turned on. Method for operating the pump system according to one of claims 12 to 17 by activating the positive displacement pump by means of the operation control device, characterized by the steps: Activating the pump motor, Detecting an operating parameter change of the pump per predetermined time interval, Operating the pump motor in the first activation mode, wherein the first activation mode is dependent on and / or influenced by the detected operating parameter change, Operating the pump motor in the second drive mode in response to reaching or exceeding the first operating parameter threshold. A method according to claim 18, characterized in that the detection of the operating parameter change takes place in the predetermined time interval after reaching or exceeding a second operating parameter threshold, which is lower than the first operating parameter threshold value.

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