DE2825128A1 - Pressure and delivery control for piston pump - has pressure sensitive adjuster to position movable brushes of pump driving motor - Google Patents

Abstract

The arrangement is for varying the pressure and delivery of a piston pump, particularly when handling solids-carrying or other high-viscosity liqs. so that delivery is reduced as pressure increases, e.g. when delivering to a filter press. The pump is driven by a commutator motor (3) with adjustable brushes (3a). The pressure downstream of the pump can be used as the input quantity to actuate a positioning element (7, 7') which is connected (8) to the cylinder (1) or the outlet manifold (1d) or the air vessel (6). The piston of the element acts as a cable (14) to adjust the angle (phi) at which the brushes are set.

Description

Process and device for regulating pressure and conveying

amount of a piston pump The invention relates to a method and Devices for carrying out the process for regulating pressure and delivery rate a piston pump, especially for pumping solids-laden or non-Newtonian High consistency liquids. Such fluids are, for example, often against Filter presses promoted, in this case with increasing filter load the delivery rate steadily decreases, whereas the pressure reaches a predetermined maximum value strives towards. For energetic reasons it is necessary to measure the power consumption of the Pump and thus the drive power of the motor with as little loss as possible Application from the pressure and flow rate resulting in the necessary hydraulic power requirement adapt. This is done by regulating the pressure and flow rate, whereby from energetic Reasons the means of throttling on the side of the fluid to be conveyed is eliminated.

It is known, in particular for solving those described at the outset Conveying task Use piston-diaphragm pumps that are trained in accordance with DT-OS 21 02 762 Pressure and flow rate of the fluid to be pumped practical lossless rules. The disadvantage of this known, energetically satisfactory solution is to see that 1. a relatively high constructive effort is to be driven, which is naturally reflected in a high price of the system and that 2. in the area of the Tipping point - this is the point of the maximum resulting from pressure and flow rate hydraulic power - a noise level is reached that is at the limit of the reasonable and permissible moves.

In view of the constantly tightening work and environmental protection regulations the second disadvantage has particular weight.

It is also known for the conveying task mentioned at the outset Use piston pumps equipped with wear-resistant piston or plunger design. Since the piston stroke is usually unchangeable, the delivery rate can be dependent on from the pressure only via the speed of the pump and therefore inevitably via the one driving it Change engine.

It has been suggested in this connection, one in his Speed very sensitively controllable thyristor controlled three-phase asynchronous motor to use. This technically most elegant solution can be for the following reasons unsatisfactory: 1. it is the most expensive of the known solutions; 2. It delivers a speed control whose quality makes more sense - and necessarily for the input the mentioned funding task does not need to be requested; 3. the s for such pump systems Maintenance staff usually available is generally not in the Lagel to maintain the control device and, if necessary, to repair it.

The registration is based on the task, one for the named funding task suitable piston pump known per se with a rotor-fed pump also known per se Three-phase shunt commutator Motor in such procedural terms to combine that 1. a sensitive and almost raffled control of pressure and delivery rate of the piston pump becomes possible; 2. the disadvantages mentioned in the introduction known solutions are avoided; 3. from the peculiarities of the runner-fed Three-phase shunt commutator motor with regard to its operating behavior and its mode of operation in cooperation with the piston pump additional, in the following Advantages described in more detail in the operation of the overall system result.

The registration is still based on the task within the framework of the proposed method advantageous embodiments of the devices for To present the implementation of the method according to structure and mode of operation as an example and describe.

The procedural task is achieved according to the invention by that a known rotor-fed three-phase current shunt commutator motor is used to drive the piston pump is used, which is characterized in that 1. in the large adjustment range provided a stepless speed change is possible without additional losses in external Resistances occur, 2. starting at the lowest speed without any special The starting elements are switched on directly, 3. the set speed is itself changes only slightly with load fluctuations in the upper range and 4. over the entire range Adjustment range a constant torque and thus a linear proportional to the Variable speed power is available, and that continues An adjustment path via an actuator directly acted upon by the conveying medium pressure is generated, which the brushes of the commutator motor directly or indirectly in such a way adjusts that a steady speed decrease takes place with increasing delivery pressure and which is further characterized in that it 1. by manual or auxiliary motor Presetting the brushes of the commutator motor for starting directly or indirectly rotated to the lowest speed position, 2. the start-up of the piston pump in the highest possible speed at the start of delivery by turning the Carries out brushing automatically and can be preset in time and 3. in the event of operational disruptions for example in the event of a sudden drop in back pressure in the pump coupled to the piston pump Consumer and subsequent shutdown of the piston pump its current control position maintains and thus fixed the brush position of the commutator motor immovable.

All things considered, the proposed solution is cheaper as the control device for the thyristor-controlled three-phase asynchronous motor. Furthermore, the other disadvantages mentioned above are avoided.

Compared to the solution with a piston-diaphragm pump, the one proposed is also cheaper when you consider the prime cost of the pump that is used for a piston-diaphragm pump is always higher than for a piston pump of the same power, included in the calculation.

Another advantage results from that compared to the known solution significantly lower noise levels over the entire operating range the proposed Has solution.

Further advantages result from the peculiarities of operational behavior and in the mode of operation of the rotor-fed three-phase shunt commutator motor. The speed control works extremely stable, because with such Motors changes the speed only slightly with load fluctuations in the upper range and the motor in the entire adjustment range with a constant, corresponding to the nominal torque Torque can be loaded. The peculiarity that the engine is always only in its the lowest speed setting can be approached by direct switching on, the filter press operation, however, a start of delivery with maximum delivery rate, i.e. Requires maximum speed, gives the possibility of the proposed according to the invention Actuator the adjustment duration of the advantageously damped adjustment movement of the brushes for a controlled start-up and run-up of the pump unit.

To carry out the method for regulating pressure and delivery rate a piston pump are two basic solutions and one the advantages of the same proposed a unifying combination of these basic solutions. With regard to to the maintenance and repair problems of control devices mentioned in the introduction under extremely rough operating conditions, purely mechanical or

mechanical-hydraulic systems favored. In principle all are Suitable actuators that are able to accept pressure changes as an input variable in To implement path changes as an output variable.

All according to the invention below for carrying out the process proposed devices for regulating the pressure and delivery rate of a piston pump are characterized in that a pressure changes known in terms of structure and mode of operation of the conveying means as input variable Xe converting path changes as output variable Xa Actuator on the pressure side of the piston pump via a connecting elbow on the Cylinder or on the manifold or on the air chamber is arranged in such a way that the conveying means applied directly to the plunger (its translational path change Xá via the with it is firmly connected rod, the threaded pin, the adjusting nut with the bracket by means of a flexible cable that transmits tensile and compressive forces to the rotary movement The brush adjustment device generating the rotation angle transfers. The immediate Acting on the plunger by the conveyor simplifies construction and handling the facility. Of course, solutions are also possible in which there is between Plunger and conveyor a buffer liquid is located.

In order to achieve a dampened change in path, the is located on both sides of the piston from the cylinder jacket, the cover and the rod or the base and the Plunger formed annulus a damping fluid, which as a result of the displacement of the Piston via a pipeline connected to openings in the cover or base between the annulus is replaced. This training leads to one's needs the brush adjustment corresponding Ubergangsverhal th of the control device.

So that the transition behavior of the control device meets the requirements can be adapted to the individual case, there is an adjustable one in the pipeline Throttle arranged.

In a further advantageous embodiment of the device is provided that when the commutator motor is disconnected from the power supply, a solenoid valve the pipeline closes. This ensures, among other things, that in the event of malfunctions, such as a sudden drop in back pressure in the pump coupled to the piston pump Consumer and subsequent shutdown of the piston pump the current control position the device and thus the brush position of the commutator motor can be fixed. Otherwise, a drop in pressure would set the control device to one of the maximum Adjust the speed in the adjustment range corresponding to the position from which a start-up not possible.

For the operating case that is usually present that the system without Counterpressure is approached, and the control device is accordingly in the position corresponding to the maximum speed is via a on the stop bracket engaging clamping lever of the piston by hand against the in the device acting restoring and frictional forces in the approach position of the brush adjustment device corresponding piston end position can be moved.

With another advantageous embodiment of the device achieves that a holding magnet when the commutator motor is disconnected from the power supply with the brake disc the drive disc of the brush adjustment device force or form-fitting in the last effective control position against that generated by the spring and the restoring force transmitted by the spring plate and the relevant components is fixed. These Solution has the particular advantage that the number of seals can be drastically reduced in the actuator because the damping fluid within the Actuator is superfluous and an extremely secure fixation of the achieved Control position by force or form fit is possible.

Another advantage of both of the basic solutions described so far containing embodiment results from the fact that in both sides of the Pistons from the cylinder jacket, the cover and the rod or the base and the plunger formed annulus is a damping fluid, which as a result of the displacement of Piston is exchanged between the annular spaces via a fixed throttle in the piston and that when the commutator motor is disconnected from the power supply, a holding magnet with the brake disc the drive disc of the brush adjustment device force or form-fitting in the last effective control position against that generated by the spring and the restoring force transmitted by the piston and the relevant components is fixed.

The start-up of the pump system is advantageously achieved in that via a return lever acting on the drive pulley, the plunger by means of Hand force against the restoring and frictional forces acting in the device in the plunger end position corresponding to the approach position of the brush adjustment device is insane.

The adjustment and setting of the pressure setpoint at which the flow rate reduction should take place by speed decrease, takes place in an advantageous embodiment the device in that over the bracket and the threaded pin for the presetting the response pressure of the actuator, the necessary preload of the spring can be adjusted is.

Examples of the device for regulating pressure and flow rate a piston pump are shown in the drawings and are explained in more detail below described. 1 shows the view of the pump assembly with its most important ones Construction groups; 1a shows the symbolic representation of the angle of rotation y of the brush adjustment Fig. 2 a diagram with the characteristic curves of pump pressure (p), pump and motor power (Ppump, PMotor) and the torque of the motor (MMotor) as a function on the delivery rate of the pump (Q) or. the pump speed (n); 3 shows a central section by an advantageous embodiment of the actuator of the device; Fig. 4 the view of another advantageous embodiment of the device with a Partial section through the holding magnet and FIG. 5 shows a central section through another advantageous embodiment of the actuator as part of the device according to Fig. 4.

The pump unit (Fig. 1) is composed of the cylinder I, the Gearbox 2, the three-phase bypass commutator motor 3 with the brush adjustment device 3a on the motor base plate 4a, the frame plate 4, the belt drive 5 and the air chamber 6. The connecting lines 1b, lc connect the distributor la and the collector 1d with the cylinder 1. The distributor la has the suction-side connection opening S, the collector 1d is the connection opening D. on the pressure side via the connection elbow 8 the actuator 7, 7 'is connected to the collector 1d. A cable 14 transmits path changes xa from the actuator 7, 7 'to the brush adjustment device 3a (Fig. La).

The pump unit of FIG. 1 has, for example, against during operation Filter press the pump characteristic p (Q or n) shown in the diagram (Fig. 2), i.e. to have pressure depending on the delivery rate or speed. In the lowest Speed setting I in the adjustment range I - II, the piston pump runs at the lowest Speed nmin and conveys the smallest flow rate Qmin against the greatest pressure Pmax <operating point A). This results in that taken up by the piston pump Power Ppump and the drive power made available by the commutator motor Motor at operating point A '. The piston pump runs in the highest speed position II with the highest speed nmax and conveys the greatest flow rate Qmax almost without Back pressure (operating point B, Pmin = O). This results in the Power Ppump absorbed by the piston pump at operating point B ', while the Motor power PMotor is present at operating point B ''. The available power surplus dP has to be accepted. The motor power PMotor increases linearly with the delivery rate Q or the speed n, since the available engine torque is in the adjustment range I - II M is constant. The required pump output pump has a maximum at tipping point K. The pump curve runs steadily from operating point A to operating point B, where point C represents a point on the characteristic curve and the pressure setpoint p5 marked, in which the delivery rate reduction due to the decrease in speed as a result of the Engagement of the actuator begins.

The actuator 7 in the embodiment of FIG. 3 consists of a Cylinder jacket 7a, which is inextricably linked to a base 7c and connected to a cover 7b is detachably connected to a split clamping ring 12, a lantern 7d and a Connection piece 7e. The connection of the actuator 7 to the connecting elbow 8 takes place via a split clamping ring 12a. Inside the actuator 7 is a plunger 9 arranged, the right into the connecting elbow 8. The rod 9a penetrates the lid 7b. The rod seal 19, 19a, the plunger seals are used for sealing 19b, 19c and 19e and the sealing rings 20, 20a are provided. Between plunger 9 and rod 9a is the piston 10 with its piston seal 19d. The spring 11 within of the cylinder jacket 7a is supported on the one hand against the bottom 7b and on the other hand against the piston 10. The piston 10 divides the space within the cylinder jacket 7a into the spaces 21 and 22, which are connected to one another via bores 16a, 16b and a pipe 16 are connected and filled with a liquid of its damping fluid. One under construction and mode of operation known solenoid valve 17, 17a, 17b, 17c closes in the currentless State the pipeline 16> in which also an adjustable throttle / is arranged is.

The rod 9a extends into a threaded pin 9b on which the Stop bracket 13b and the nut 13 with its bracket 13a countered against each other are arranged. The cable 14, which transmits tensile and compressive forces, is on the bracket 13a attached. Is on an arm 15a rigidly connected to the cylinder jacket 7a a fork-shaped in the area of the slotted stop bracket 13b the pivot point 15c pivotable clamping lever 15 attached.

The task of the actuator 7 is to act on the plunger 9 pressure changes, which represent the input variable Xe, in translational path changes, also as Output variable Za denotes to reshape. The device works as follows: pressure changes, as they are based on the characteristic curve described in FIG. 2, for example during operation the piston pump against filter presses occur, steer above point C, if they are positive, the plunger 9 in conjunction with its piston 10 against the biasing force the spring 11 in the direction of the cover 7b. The change in path xa is made via the threaded pin 9b, the nut 13 and the bracket 13a on the cable transmitting tensile and compressive forces 14 transferred. This adjusts the brush adjustment device at its other end 3a in such a way that the Coumutator motor 3 runs a little slower. Since the position of the Plunger 9 clearly depends on the level of the pressure change Ze, it results first in any case a brush and thus speed adjustment, which is a reduction the flow rate depending on the pressure according to the characteristic curve. Further positive pressure changes cause a further steady reduction in the delivery rate in the order described. Negative changes in pressure call for analogous changes of the individual parameters in reverse order. At the end of the funding cycle (Operating point A), which begins in operating point B, the plunger 9 has its on Fig. 3 related extreme left position reached and the commutator motor 3 to its Lower speed nmin in adjustment range I - II.

When the commutator motor 3 is disconnected from the mains, the solenoid valve 17, 17a, 17b, 17c also de-energized and closes the pipeline 16. One movement of the piston, which during the control process flows through the flow in the throttle 18 liquid damping fluid was damped, from this situation is no longer possible. The lowest speed setting, which is also the starting position for the following The conveying cycle remains fixed, so that the Rammutator motor 3 is then switched on directly can be. Since the new conveying cycle begins with zero back pressure, the moves Plunger 9 due to the damping by means of the adjustable throttle 18 of the Pipeline 16 exchanged between the spaces 21 and 22 liquid damping fluids slowly into its possible opposite position and thus causes over the one connected with it Adjustment mechanism a steady, slow increase in speed up to the maximum Speed n. The time for ramping up the speed is via the adjustable throttle 18th adjustable. According to the characteristic p (Q), the is already running The delivery cycle described from the plunger 9 is at the beginning of the delivery cycle at zero back pressure in its extreme right-hand position in relation to FIG. 3, the the maximum speed of the commutator motor 3 defines, it is a start-up only possible if the plunger 9 via the clamping lever 15 by adjusting the edge in the extreme counter position is shifted. It is electrically ensured that the Solenoid valve 17, 17a, 17b, 17c, the pipeline 16 opens. The same manual intervention is also necessary for every start-up process in which the plunger 9 is not in its extreme left position, since the commutator motor 3 is always only with the lowest speed nmin in the adjustment range I - II can be switched on and its line contactor is locked against being switched on in any other position.

In another advantageous embodiment of the device (Fig. 4) is within the actuator 7 'on the filling of the spaces 21 and 22 with a Damping fluid dispensed with. The piston 10 becomes the actuator through the annular gap 19f 7 <Fig. 3) a spring plate 10 'against which the spring 11 is supported. On holes in the cover 7b 'and base 7c', as well as on all of the seals shown in FIG. 3 be waived. Only the plunger seal 19e, which allows the conveying means to pass through from the connecting elbow 8 into the lantern 7d is necessary. The rest The structure of the actuator is the same as that described in FIG.

The change in path, referred to as the output variable xa, is measured by means of a Tensile and compressive forces transmitting cable 14 on the brush adjustment device 3a transferred to which a drive pulley 23 is attached, which is by a reset lever 25 can be adjusted manually.

silver of the brush adjustment device 3a, fixed to the commutator notor 3 of its connected is a holding magnet known per se in structure and operation 24a, 24b, 24c arranged, which with its on the axially displaceable holding magnet valve 24a attached brake disk 24 forcefully or foreschldssig on the underlying Drive pulley 23 acts.

The actuator 7 'works in its entirety like the actuator 7 of FIG. 3 when the influences of the damping fluid are eliminated. Fixing the In contrast to the actuator 7, the plunger 9 in any position takes place through the holding magnet 24a, 24b, 24c, which is in the de-energized state over its brake disc 24 the drive disc 23 of the brush adjustment device 3a form- or holds firmly in place.

The reset lever 25 is dimensioned so that the plunger 9 by means of hand force against the restoring and frictional forces acting in the device Approach position of the brush adjustment device 3a corresponding plunger end position can be moved is.

Another advantageous embodiment of the device is characterized is characterized in that the plunger movement by means of a in rooms 21 and 22 located via a throttle 16c in the piston 10 between the spaces 21 and 22 interchangeable The damping fluid is damped. Fig. 3), but the fixation of the plunger 9 in any position via a holding magnet 24a, 24b, 24c in connection is carried out with a brake and drive disk 24 and 23 (according to FIG. 4).

Claims (10)

P A 17 h 'N 27 A N S F R U C H 1. Method for regulating pressure and delivery rate of one equipped with a wear-resistant piston or plunger design Piston pump, especially for pumping solids-laden or non-Newtonian Liquids of high consistency, with the maximum flow rate of the conveyor without, with a decreasing flow rate against a steadily increasing and with a minimum Conveying against constant maximum back pressure is to be conveyed with an after build-up and mode of operation known per se, single or double-acting, single or multi-cylinder Piston pump, characterized in that a per se for driving the piston pump well-known rotor-powered three-phase current shunt commutator motor used which is characterized in that 1. in the large adjustment range provided a stepless speed change is possible without additional losses in external Resistances occur, 2. starting at the lowest speed without any special The starting elements are switched on directly, 3. the set speed is itself changes only slightly with load fluctuations in the upper range and 4. over the entire range Adjustment range a constant torque and thus a linear proportional to the Variable speed power is available, and that continues via a the actuator directly applied by the conveying medium pressure generates an adjustment path, which adjusts the brushes of the commutator motor directly or indirectly in such a way, that with increasing fluid pressure there is a steady decrease in speed and that is further characterized in that it 1. by manual or auxiliary motor Presetting the brushes of the commutator motor for starting immediately or indirectly rotated to the lowest speed position, 2. starting up the piston pump to the highest possible speed at the start of delivery by turning the Carries out brushing automatically and can be preset in time and 3. in the event of operational disruptions for example in the event of a sudden drop in back pressure in the pump coupled to the piston pump Consumer and subsequent shutdown of the piston pump its current control position maintains and thus fixed the brush position of the commutator motor immovable. 2. Device for performing the method according to claim 1 thereby characterized in that a pressure changes known in terms of structure and mode of operation of the conveying means as input variable Xe converting path changes as output variable xa Actuator (7, 7 ') on the pressure side of the piston pump via a connecting elbow (8) on the cylinder (1) or on the distributor (Id) or on the air chamber (6>) is that the conveyor acts directly on the plunger (9), its translational Change of path xa via the rod (9a) firmly connected to it, the threaded pin (9b), the adjusting nut (13) with the bracket (13a) by means of a tensile and compressive force transmitting flexible cable (14) on which a rotary movement by the angle of rotation (r) generating Brush adjustment device (3a> transfers. 3. Device to claim 2, characterized in that in the one on both sides of the piston (10) from the cylinder jacket <7a), the cover (7b) and the rod (9a) or the bottom (7c) and the plunger (9) formed annular space (21) or (22) there is a damping fluid that as a result of the displacement of the Piston (10) via one with openings (16a, 16b) in the cover (7b) respectively. Floor (7c) connected pipeline (16) exchanged between the annular spaces (21,22) will. 4. Device according to claim 3, characterized in that upon separation the commutator motor (3) from the power supply a solenoid valve (17, 17a, 17b, 17c) the pipeline (1) closes. 5. Device according to one of claims 3 and 4, characterized in that an adjustable throttle (18) is arranged in the pipeline (16). 6. Device according to one of claims 3 to 5, characterized in that that via a clamping lever (15) acting on the stop bracket (13b) the piston (10) by means of hand force against the restoring and frictional forces acting in the device into the piston end position corresponding to the starting position of the brush adjustment device (3a) is insane. 7. Device according to claim 2, characterized in that upon separation the commutator motor (3) from the power supply a holding magnet (24a, 24b, 24c) with the brake disc (24) the drive disc (23) of the brush adjustment device (3a) non-positively or positively in the last effective control position against that of the spring (11) generated and from the spring plate (10 ') and the components (9a, Ab, 13, 13a, 14) fixed restoring force transmitted. 8. Device according to claim 2, characterized in that in the on both sides of the piston (10) from the cylinder jacket {7a) dem, Dcka7, Wh) and the Rod (9a) or the bottom (7c) and the plunger (9) formed annular space (21) or (22) is a damping fluid, which as a result of the displacement of the Piston (10) via a fixed throttle (16c) in the piston (10) between the annular spaces (21, 22) is exchanged and that when the commutator motor (3) is separated from the Power supply a holding magnet (24a, 24b, 24c) with the brake disc (24) the drive disc (23) of the brush adjustment device 3a) non-positively or positively in the last effective control position against that generated by the spring (11) and the piston (10) and the restoring force transmitted to the components (9a, 9b, 13, 13a, 14) is fixed. 9. Device according to one of claims 7 and 8, characterized in that that via a return lever (25) acting on the drive pulley (23) of the Plunger (9) by means of hand force against the return force acting in the device and frictional forces in the starting position of the brush adjustment device (3a) corresponding plunger end position is displaceable. 10. Device according to one of claims 2 to 9, characterized in that that over the bracket (13b) and the threaded pin (9b) for presetting the response pressure of the actuator (7, 7 ') necessary bias of the spring (11) is adjustable.