DE102009020414A1 - Homogenization of the flow rate in oscillating positive displacement pumps - Google Patents

Abstract

In a method for equalizing the flow rate in oscillating displacement pumps whose drive is effected by means of a drive motor via a rotating shaft, the procedure is such that the generation of the fluid flow in a conveying line (5) by means of at least two oscillating displacement pumps (1, 2) takes place Drive motors (6, 7) are controlled such that the total flow rate generated in the delivery line (5) is substantially uniform or constant. The device provided for carrying out this method according to the invention is characterized by at least two oscillating positive displacement pumps (1, 2) whose pressure line (3, 4) for superimposing the individual flow rates on a common feed line (5) is connected and each having a drive motor (6, 7), which are operable without mechanical coupling in electronic synchronization to achieve a substantially uniform or constant sum flow.

Description

The The invention relates to a method for equalization the flow rate at oscillating displacement pumps according to the preamble of claim 1.

The The invention also relates to a device for implementation this method according to the preamble of the claim 6th

At the Operation of oscillating positive displacement pumps is fundamental Considerations desired, a largely to achieve constant flow rate. This is already true because otherwise in the pressure or delivery line disadvantageous Appearances occur. These consist z. B. in that at each Pressure stroke creates a pressure pulsation in the delivery line, which adversely affect the lines of the entire system can and therefore by means of separate pulsation damper and the like. Must be suppressed or prevented.

Around therefore a largely constant flow at oscillating For example, it is already possible to reach positive displacement pumps known not to build pumps as a single pump, but at least as a triple pump with gleichmäßgiem eccentric offset provided. Due to the superimposition of the flow rates decreases with increasing cylinder number, the pulsation of the flow from. However, this is not enough for many cases so additional measures for pulsation damping become necessary. However, this requires a considerable constructive Effort.

It is also known ( DE 198 49 785 C1 ), to the desired flow adjustment of the oscillating positive displacement pump to use their drive shaft itself, in such a way that a transition from the rotational movement of the drive shaft in a pivoting movement or vice versa, to provide various desired flow settings. Such a method has been well proven in practice. However, this does not yet make it possible to achieve a continuous or even flow of the total fluid to be delivered, since there is still no pumping during the suction stroke of the pump, which interrupts the otherwise achieved constancy of the flow.

Of the The invention is therefore based on the object, the method of the generic To design the way of eliminating the described disadvantages in such a way that it can be achieved by means of simple constructive means economic effort to achieve a largely uniform or constant flow rate allows.

Furthermore is intended a device for carrying out this method be created, which is easy to operate.

These Task is with the method according to the invention solved by the features of claim 1. advantageous Embodiments thereof are in the further claims described.

The Features of the inventively created device emerge from claim 6. Advantageous embodiments thereof are listed in the further claims.

the Inventive method for equalization the flow rate at oscillating displacement pumps The essential idea underlying the generation of the fluid flow in a conveying line by means of at least two oscillating Positive displacement takes place, the drive motors so be controlled, that the total generated flow in the delivery line largely evenly or constant.

According to the invention furthermore provided that the positive displacement pumps in the composite be operated together without mechanical coupling.

It is within the scope of the invention, that the positive displacement pumps be operated electronically synchronized so that a nearly pulsation-free, uniform flow rate (volume flow) is generated in the common delivery line.

Conveniently, the process according to the invention can be operated in this way be that the drive motor of each positive displacement pump in its speed is changed so that the superimposed Flow rates of positive displacement pumps a largely constant sum flow yield.

Special Benefits arise when the shaft of the drive motor of each positive displacement pump for Achieving the constant characteristic of the total flow rate performs an adapted rotational movement.

The inventive device for implementation the aforesaid method is provided with at least two oscillating positive displacement pumps, their pressure line for superimposing the individual flow rates is connected to a common conveyor line and each having a drive motor without mechanical coupling in electronic synchronization to achieve a largely uniform or constant total flow are operable.

Advantageously, the drive of each displacement pump is a highly dynamic drive. This may be a servomotor, preferably a permanent magnet three-phase synchronous servo motor.

It is within the scope of the invention, that the positive displacement pumps Diaphragm pumps are.

With The invention thus makes it possible, due to the targeted performed superimposition of the flow rates two single pumps, the pressure pulsation in the common delivery line Even without pulsation damper to prevent and at the same time to achieve a largely constant flow rate. This done by exact electronic synchronization of the mechanical uncoupled positive displacement pumps.

Finally, in order to check whether the desired constant characteristic of the delivery flow is achieved, various methods are already known (US Pat. DE 35 46 189 C2 ), which consist, for example, in that the pressure curve in the pump cylinder is measured by means of pressure sensors, whereupon the actually conveyed volume flow of the pump is then calculated from the detected measured values via the kinematic law of motion of the pump piston.

The Invention will be hereinafter in the form of an embodiment explained in more detail with reference to the drawing. This shows in:

1 schematically the arrangement of two mechanically uncoupled oscillating displacement to equalize the total flow rate;

2a -D different diagrams of pump readings, plotted against time t, to illustrate the achievement of a constant fluid velocity and thus a uniform flow rate, with a pump delivery of 100%, as well as

3a -C are various graphs of corresponding pump readings plotted against time t, with a reduced pump delivery rate of approximately 90%.

How out 1 The drawing shows, for carrying out the method according to the invention in the illustrated embodiment, two oscillating positive displacement pumps in the form of diaphragm pumps 1 . 2 provided, the pressure lines 3 . 4 to a joint support line 5 are connected.

The mechanically uncoupled diaphragm pumps 1 . 2 each have a drive motor 6 respectively. 7 on, which is designed as a highly dynamic drive. This is preferably a servo motor, in particular a permanent-magnet three-phase synchronous servo motor.

The drive motors 6 . 7 the two diaphragm pumps 1 . 2 are operated by exact electronic synchronization such that a substantially uniform or constant sum flow in the common delivery line 5 is reachable.

This procedure, which is operated by the method according to the invention, is illustrated by the individual diagrams in FIG 2a -D, where the pump delivery rate is 100%. Here, for the sake of simplicity, only the pressure stroke of each diaphragm pump 1 . 2 represented, wherein the respective left half of the diagrams the respective measured value course during the pressure stroke of the diaphragm pump 1 represents, while the corresponding right half of the diagram the measured value course in dashed form during the pressure stroke of the diaphragm pump 2 shows.

diagram 2a shows the course of the piston travel over time t for both diaphragm pumps 1 . 2 , Because this - unlike the prior art - due to the special operation of the drive motors 6 . 7 the two diaphragm pumps 1 . 2 is a constant course, also shows how out 2 B can be seen, a constant piston speed.

This is not least caused by the fact that the angular velocity of the eccentric shafts of the respective diaphragm pumps 1 . 2 plotted against time t, the course according to 2c , ie - also in contrast to the prior art - each have a high initial and final speed at a constant course between these two basic values.

Finally the diagram shows according to 2d clear that due to the operation of the invention, a constant fluid velocity, plotted over the time t results. This directly has a constant flow in the delivery line 5 result.

The diagrams according to 3a -C show different measured values of the diaphragm pump 1 (solid line) and the diaphragm pump 2 (dashed line), respectively, apply over time t, with the diaphragm pumps 1 . 2 each have only a reduced flow rate of about 90 ° C. Here the diagram shows according to 3a the fluid velocity applied over time t without compensation of the loss due to the "dead compression path hK" occurring at the beginning of the pressure stroke. However, this loss of fluid velocity is extremely low compared to the prior art, so it is negligible.

If this loss of value is nevertheless to be compensated, then a representation of the fluid velocity over time t is obtained 3b , in which the degree of promotion is compensated. For this purpose, the "dead compression path hK" occurring at the beginning of the compression stroke must be known or automatically determined. A corresponding method for this purpose is for example from the DE 35 46 189 C2 known.

As for this 3c can be seen, the pump piston is brought after completion of the suction stroke in the position hK before the actual delivery stroke begins. The piston travel then starts at hK, ie the fluid is displaced immediately in the pressure stroke.

• – aus einer Ansaugphase, in der das Fluid in eine Pumpenkammer angesaugt wird,
• – einer Kompressionsphase, in der das angesaugte Fluid auf Förderdruck gebracht wird,
• – einer Förderphase, in der ein Teil des komprimierten Fluids aus der Pumpenkammer ausgestoßen wird, und
• – schließlich einer Dekompressions- bzw. Expansionsphase, in der das in der Pumpenkammer verbliebene Fluid wieder auf Ansaugdruck gebracht wird. Hierbei benötigt jede oszillierende Verdrängerpumpe für die Kompression des Fluids vom Saugdruck auf den Förderdruck einen bestimmten geringen Kolbenweg, den sog. toten Kompressionsweg hK, der in der Kompressionszeit zurückgelegt wird.

To understand the concept of "dead compression path hK" is based on the known fact that each oscillating positive displacement pump has a delivery cycle. This one exists

• From a suction phase, in which the fluid is sucked into a pump chamber,
• A compression phase in which the sucked fluid is brought to delivery pressure,
• A delivery phase in which a part of the compressed fluid is expelled from the pump chamber, and
• - Finally, a decompression or expansion phase in which the remaining fluid in the pump chamber is brought back to suction pressure. In this case, each oscillating positive displacement pump for the compression of the fluid from the suction pressure to the delivery pressure requires a certain small piston travel, the so-called dead compression travel hK, which is covered in the compression time.

Regarding not explained in detail above finally, expressly to the claims as well as the drawing referenced.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19849785 C1 [0005]
• - DE 3546189 C2 [0019, 0032]

Claims (8)

Method for equalizing the delivery flow in oscillating displacement pumps, the drive of which is effected by means of a drive motor via a rotating shaft, characterized in that the generation of the fluid delivery flow in a delivery line ( 5 ) by means of at least two oscillating positive displacement pumps ( 1 . 2 ) whose drive motors ( 6 . 7 ) are controlled such that the total generated flow in the delivery line ( 5 ) is largely uniform or constant. Method according to claim 1, characterized in that the positive displacement pumps ( 1 . 2 ) are operated in combination with each other without mechanical coupling. Method according to claim 1 or 2, characterized in that the positive displacement pumps ( 1 . 2 ) are operated synchronized electronically such that a virtually pulsation-free uniform flow rate (volume flow) in the common delivery line ( 5 ) is produced. Method according to one of the preceding claims, characterized in that the drive motor ( 6 . 7 ) of each positive displacement pump ( 1 . 2 ) is changed in its speed such that the superimposed flow rates of the positive displacement pump ( 1 . 2 ) give a largely constant total flow. Method according to one of the preceding claims, characterized in that the shaft of the drive motor ( 6 . 7 ) of each positive displacement pump ( 1 . 2 ) performs an adapted rotational movement to achieve the constant characteristic of the sum flow. Device for carrying out the method according to one of the preceding claims, characterized by at least two oscillating positive displacement pumps ( 1 . 2 ), whose pressure line ( 3 . 4 ) for superimposing the individual delivery flows on a common delivery line ( 5 ) and each having a drive motor ( 6 . 7 ), which are operable without mechanical coupling in electronic synchronization to achieve a substantially uniform or constant cumulative flow. Device according to claim 6, characterized in that the drive ( 6 . 7 ) of each oscillating positive displacement pump ( 1 . 2 ) is a highly dynamic drive, in particular a servo motor, preferably a permanent-magnet three-phase synchronous servo motor is. Device according to claim 6 or 7, characterized in that the oscillating displacement pumps ( 1 . 2 ) Diaphragm pumps are.