WO2002004812A1

WO2002004812A1 - Positive displacement pump

Info

Publication number: WO2002004812A1
Application number: PCT/EP2001/007776
Authority: WO
Inventors: Manfred Roth
Original assignee: Tankol Gmbh
Priority date: 2000-07-08
Filing date: 2001-07-06
Publication date: 2002-01-17
Also published as: EP1299643B1; EP1299643A1; AU2001291662A1; DE10132298A1; DE50107621D1; ATE306019T1

Abstract

The invention relates to a positive displacement pump, especially a reciprocating positive displacement pump, comprising at least one piston (30) that is displaced relative to a pump housing, thereby changing the volume of a working chamber. A pump body (22) is received in a rotor sleeve (20) that rotates about said pump body. Said pump body is provided with longitudinal grooves extending from its peripheral surface (23) that receive energy accumulators (40) associated with the pistons (30). Every piston (30) is associated with a bolt- or needle-shaped body (36) on its front face facing the rotor sleeve (20). The inner surface (21) of the rotor sleeve (20) rests against and rolls off on the outer surfaces of said bodies (36). The pump body (22) has an eccentric cross-section in the rotor sleeve (20). An annular gap (19) present between those two parts has a gap width (t) that tapers in the peripheral direction. Preferably, the inner bore of the rotor sleeve (20) is eccentrically disposed in said rotor sleeve.

Description

DESCRIPTION

displacement

The invention relates to a positive displacement pump - in particular an oscillating positive displacement pump - with at least one piston which is relatively movable in a pump housing while changing the shape of a working space.

Piston machines offer a work space that changes periodically and is filled with a fluid; its pressure changes with compression, decreases with expansion. The essential geometric size is the stroke volume as the change in the working space caused by the displacer during a cycle.

In the case of piston pumps - so-called oscillating displacement pumps - a piston in a closed displacement chamber conveys the displacement volume via pressure-dependent opening elements against system pressure. The theoretical conveying work is formed from the stroke volume and the differential pressure from the suction to the pressure side, the stroke volume arises from the movement of the piston between a lower and an upper dead center. The movement is usually converted into a reciprocating movement by converting a rotary movement of the drive unit via a "crank"; the constant rotary movement of the drive is converted into a non-constant stroke movement of the pump piston. The consequence of this is that the fluid to be delivered is moved with a relatively high change in the flow rate - oscillating flow - in the displacement of the pump. This so-called pulsation of the flow can be detected by measuring the pressure pulsation. The disadvantages that may result from this are known. Pumps of this type are generally driven in the classic unit design, ie the pump and motor are connected on a base plate or via a lantern in the alignment of both shaft axes by a coupling element which transmits the necessary drive power. The direct coupling of the motor is an exception; Here, the pump shaft is designed as a hollow shaft on the drive side in such a way that the motor shaft is inserted and a torque can then be transmitted.

10

Further exceptions are the so-called hermetically sealed pump structures. Any kind of leakage on the shaft seal of the emerging pump shaft must be avoided due to toxic, aggressive or flammable fluids

Be 15. This is done either by installing known magnetic couplings between the pump shaft and the unit coupling, or by the tight connection of the motor housing to the pump housing by means of a hermetic seal between the stator and the rotor of the motor in a so-called.

Ξ0 "canned motor" version. Such hermetically sealed pumps are extremely expensive. With the magnetic coupling, there is also the fact that any slip between the outer and inner rotor must be avoided by large safety surcharges in the design, since there is no restart after a

Ξ5 brief slip between the two rotors is possible.

Knowing this state of the art, the inventor has set himself the goal of producing a pump that is always hermetically sealed without a complex pump / motor construction.

30

The teaching according to the independent claim leads to solving this problem; the subclaims indicate favorable further training. In addition, all combinations of at least two of the

35 writing, the drawing and / or the features disclosed features. According to the invention, a pump body is mounted in a rotor sleeve and is provided with longitudinal grooves extending from its circumferential surface for receiving pistons therein — associated with energy stores; Each piston is assigned a bolt-like or needle-like body on its head surface facing the 5 rotor sleeve, on the outer surface of which the inner surface of the rotor sleeve rests. The latter should advantageously be rotatably mounted around the pump body.

10 According to a further feature of the invention, the pump body runs eccentrically in cross section in the rotor sleeve; in a particularly favorable embodiment, the inner bore of the rotor sleeve is arranged eccentrically in this. In any case, there is an existing between these two parts

15 ner annular gap of tapering gap width in the circumferential direction.

Instead of the rotor shaft of the classic drive, it becomes the rotor sleeve with an eccentrically arranged inner bore

Ξ0 used. Within this eccentric inner bore, the pump body is arranged with two or more longitudinal grooves - arranged radially and evenly distributed on the circumference - centrally to the pivot point of the drive motor so that the pistons inserted into the longitudinal grooves are guided by the rotating one

Ξ5 eccentric bore of the rotor sleeve must be forced into a lifting movement.

The longitudinal grooves in the pump body are advantageously arranged at an angle to the cross-section of the diameter; the cross-sectional longitudinal axis of the longitudinal groove delimits an angle of approximately 20 ° to 40 °, in particular approximately 25 °, with one of the diameter lines of the pump body.

A preferred positive displacement pump is characterized by two 35 pairs of longitudinal grooves, the orifices of which are offset from one another by 90 ° on the circumferential surface of the pump body; because two such longitudinal grooves are approximately opposite each other on a straight line in diameter. associated mouths, the mouth centers according to the invention being located on different sides of the assigned diameter straight line at a distance from it, that is to say they are offset from one another. Of course, the invention is not limited to the configuration described with two pairs of longitudinal grooves; a larger number of such pairings can also be provided.

It has proven to be advantageous to provide a channel-like longitudinal indentation in the head surface of the cross-sectionally flat piston as a bearing for the bolt-like or needle-like body formed by a bearing needle; approximately at right angles to the longitudinal indentation or the top surface of the flat piston should run in this recesses for receiving a force accumulator. Each of these recesses is preferably located next to the cross-sectional longitudinal axis of the longitudinal groove; The purpose of this offset is to increase the ridge surface on the bearing pressure side. Thanks to the energy storage device, which is designed as a coil spring and is supported on the groove base of the longitudinal groove, the flat piston is held at a variable distance from the groove base. The energy accumulator ensures that the piston is fixed without play via the head needle bearings to the eccentric rotor sleeve.

In the context of the invention, the underside of the flat piston and the bottom of the groove determine the height of a conveying or working space which is delimited on both sides by groove walls. This should be connected to the needle bearing by at least one bore provided between the underside of the flat piston and its longitudinal molding.

According to the invention, the rotor sleeve in the displacement pump has ball bearings on both ends and is closed on both ends by a pump cover. According to the invention, these pump covers, which are arranged on the right and left of the pump body, have corresponding valves in order to generate a delivery process of the delivery medium from the suction to the pressure side of the pump according to the invention from the stroke movement of each flat piston. The Individual delivery rooms or delivery chambers - equal to the number of flat pistons selected in each case - are combined in the pump covers and form the connections for the suction and pressure lines via the motor covers.

It is within the scope of the invention that this structural design can be represented both in a direct current and in an alternating current motor version.

In addition, it has proven to be advantageous that both lubricating and hardly lubricating fluids can be pumped by appropriate choice of materials. The structural design always represents an "inline design" in accordance with the pump standards, with no "assembly construction" being required.

According to a further feature of the invention, the choice of the number of flat pistons and the choice of a relatively wide range of changed strokes - changing the eccentricity of the inner bore of the rotor sleeve - for a "size" means the delivery quantities "quantity" and "pressure" in changed a wide range.

A particular advantage over conventional positive displacement pumps is improved security against "seizing" of the delivery elements, since the delivery pressure always decreases on both sides in the lubrication gap between the pump body and the flat piston, whereby the pressure component from the delivery chamber does not act in the direction of the slide bearing surfaces, as is the case with for example, the case with a screw pump. In the subject matter of the present invention, with increasing tangential force on the flat pistons - due to the increase in the transmitted torque of the rotor sleeve - the hydrostatic pressure in the lubricating gap increases to the same extent with increasing delivery pressure. As is well known, the classic design of the rotor of a three-phase motor consists of the laminated core of the cage rotor on a drive shaft with the cast-out cage grooves as a short-circuit rotor. If you replace the drive shaft - within the framework of the necessary minimum dimensions of the cage bars - with the rotor sleeve according to the invention and change the motor housing cover in the manner described, then the complete motor / pump / unit is formed. With such a design, there is no shaft seal, which is commonly known as the weakest link in pumps with an emerging shaft end. At the same time, the "hermetically sealed" pump can be achieved without additional additions at a cost which corresponds approximately to that of a simple unit structure. The alignment of the motor and pump which is usually necessary in the case of the classic assembly structure in order to ensure the proper functioning of the intermediate clutch is also eliminated in the present invention.

If the required speed control of this pump and / or when using higher speeds, the - mentioned - design as a DC or single-phase machine is also possible; Here the rotor winding is replaced by a package of permanent magnets - known from the magnetic couplings. This enables small designs (here the system diameter) and opens up a wide field of application for the large-scale production of small pumps with high pressure ranges.

In any case, only the suction pressure of the pumped medium is created in the stator chamber, since the leaks that occur are discharged both by the play of the flat piston in the pump body and by the needle bearings through a connection to the suction chamber of the pump. Instead of the usual drive systems with direct current, alternating current or three-phase current, the use of a magnetic coupling has proven to be particularly favorable in contrasting the rotor sleeve, already discussed, connected to an inner magnetic element with an outer rotor which carries a corresponding magnetic counter element; the two magnetic elements form a magnetic coupling; Through the use of a hermetically sealed magnetic coupling, the two torque-transmitting and magnet-equipped rotors are sealed by means of a can.

The drive takes place by means of a toothed or V-belt engaging on that outer rotor. This makes it possible to use it as a flange-mounted auxiliary unit on all types of engines. If one replaces the outer rotor with magnets, including the toothed or V-belt elements, for example by a DC or commutatorless three-phase stator, the use of the pump generally described above can be seen; Because of the dimensions, this pump is particularly suitable for mobile use.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in

1: a partially sectioned front view of a tangential piston pump;

Fig. 2: a partially sectioned side view of the tangential piston pump

DC machine;

3 shows a partially sectioned side view of the tangential piston pump as a three-phase short-circuit machine;

FIG. 4: the longitudinal section through the tangential piston pump, enlarged compared to FIG. 3;

5 shows an enlarged cross section through a central part of FIG. 1 and its section line V - V;

FIG. 6: a detail from FIG. 5;

7, 8: a partially sectioned front view and an equally partially sectioned front view of another embodiment of a

Pump. In the case of a tangential piston pump 10, a rotor sleeve 20 of the inner diameter d, which surrounds a pump body 22 of circular cross-section of the diameter e, is mounted in a tubular housing 16 - closed on both ends by fastening strips 12 having housing covers 14 - in the region of ball bearings 18.

The longitudinal axis of the pump body 22 is denoted by A, and four longitudinal grooves 24 are arranged in it with a groove base 26 which is rounded in the form of a partially circular circle in such a way that, in the example shown, their cross-sectional longitudinal axes Q with the central cross-sectional axis M, which defines a straight line, or the transverse axis perpendicular to this B of the pump body 22 limit an angle w of approximately 25 °. 5, the center of the mouth 25 of the longitudinal grooves 24 on the body circumference is offset laterally by a dimension i to the corresponding cross-sectional central axis M or the transverse axis B, and the cross-sectional longitudinal axes Q of the two longitudinal grooves 24 on the cross-sectional central axis M run parallel to one another as well as the cross-sectional longitudinal axes Q of the two longitudinal grooves 24 assigned to the transverse axis B.

Each longitudinal groove 24 of cross-sectional width a receives a flat piston 30, in the outwardly directed head surface 32 of which a bearing needle 36 rests in an indentation 34 extending in its longitudinal direction - the width b of its part-circular cross-section; On one side of the cross-section in a dimension z - as the distance between the cross-sectional longitudinal axis Q of the longitudinal groove 24 and the parallel cross-sectional axis F of this longitudinal indentation 34 - the longitudinal indentation 34 extending eccentrically in the flat piston 30 is the wider strip of the top surface 32 to a desk surface 33 Width f bevelled. When the rotor sleeve 20 rotates, the contact between its inner surface 21 and the surface of the bearing needles 36, which partially projects beyond the circumferential surface 23 of the pump body 22, results in a rolling movement as in a needle bearing. If - as illustrated in FIG. 5 - the inner diameter d of the rotor sleeve 20 is arranged eccentrically to the outer diameter e of the pump body 22, an annular gap 19 with itself - in FIG. 5 - downwards is created between that peripheral surface 23 and the inner surface 21 of the rotor sleeve 20 tapering gap width t and, when the rotor sleeve 20 rolls on the bearing needles 36, a reciprocating movement of the flat pistons 30 with a stroke which corresponds to twice the eccentricity of the inner diameter d of the rotor sleeve 20.

When the flat piston 30 is lifted in the pump body 22 against a force accumulator 40 provided in a recess 38 running eccentrically to the longitudinal cross-section axis Q and parallel to this in flat pistons 30, a volume becomes in a delivery space 28 laterally delimited by the groove walls 27 between the piston underside 31 and Groove base 26 compressed. By appropriate arrangement of valves 42 in the suction and pressure side pump covers 44, 44 _a on the end faces of the pump body 22, a conveying work can be carried out by the lifting movement of the flat pistons 30. The size of this theoretical promotion (ΔQ / Δt or generally in 1 / min) is linearly dependent:

"Q _h eo _r ." = Number of pistons * piston area * stroke * speed,

By choosing a flat piston 30, a minimum stroke is sufficient for the representation of the delivery volume - with a corresponding selection of the number of pistons. For a series in a delivery range of, for example, 40 to 1400 rpm and a speed of 2950 min ^A -l, the maximum stroke is in the range of 2 to 6.5 mm. The consequence of this is that the known disadvantages of oscillating displacement pumps with regard to the pulsating flow can be reduced to a minimum. If there is more than one flat piston 30, the pressure pulsation which forms at the pressure port of the pump 10 is thus also greatly reduced. The piston movement during the suction stroke, ie the running of the flat piston 30 in the area of the diameter increase or the positive eccentricity of the inside diameter d of the rotor sleeve 20 takes place through the pretensioning force of springs inserted into the recesses 38 of the flat piston 30 as a force accumulator 40 and the lubrication of the needle bearing on Piston head 32 of the flat piston 30 through the medium through the arrangement of holes 46 or the like. Connections of the delivery chamber 28 remaining in the longitudinal groove 24 to the bearing recess or longitudinal indentation 34 in the piston head 32. A wide range of the lubricating properties of the delivery medium (also v <1 mm ^Λ 2 / sec.) Can be achieved by appropriate choice of material and surface of the needle bearing parts hydrostatic lubrication can be maintained since the lubrication pressure always increases with the delivery pressure.

In the embodiment described above, the motor stator is not sealed off from the pumped medium. If required, the stator can be given a thin-walled tube made of the classic materials of this application, as in the known "canned motor". For aggressive media - e.g. in chemistry - due to the negligible lubrication limit due to the lack of plain bearing conditions, a wide range can be covered by appropriate choice of materials for pump body parts and the flat pistons.

Since no classic fan can be arranged on the motor shaft in this construction, the stator housing must be provided with appropriate surface cooling. In any case, however, a certain amount of the magnetic heat loss is absorbed by the circuit of the leakage currents that flow through the bearings on the stator to the suction side and by the heat conduction of the squirrel-cage rotor / rotor sleeve. Instead of drive systems with direct, alternating or three-phase current, the rotor sleeve 20 can also be driven via a magnetic coupling. For this purpose, the rotor sleeve 20 of the tangential piston pump 10 _a according to FIGS. 7, 8 carries at least one sleeve-like magnetic element 50 on its axially parallel outer contour. Between this and a magnetic counter element 51 of an outer rotor 54 the inner magnet element 50 runs in a gap 56 parallel to the longitudinal axis A. hermetically sealing - pot wall 58 of a containment shell 60 encompassed by that outer rotor 54. This is assigned at the end to a carrier ring 62.

The outer rotor 54 on the magnetic coupling 52 formed by the magnetic elements 50, 51 is driven by a toothed or V-belt 64.

In the case of this pump 10 _a , the drive torque - coming from an outer shaft - is supplied to the pump body 22 on the inside via the magnetic coupling 52, which in particular detects the two rotors 20, 54.

Claims

Displacement pump (10, 10 _a ), in particular oscillating displacement pump (16), with at least one piston (30) which can be moved relatively in a pump housing while changing the shape of a working space,

characterized,

that a pump body (22) is mounted in a rotor sleeve (20) and is provided with longitudinal grooves (24) extending from its peripheral surface (23) for receiving pistons (30) assigned therein to energy stores (40), each piston pointing at it to the rotor sleeve Head surface (32) is assigned a bolt or needle-like body (36), on the outer surface of which the inner surface (21) of the rotor sleeve rests.

2. Displacement pump according to claim 1, characterized in that the rotor sleeve (20) is rotatably mounted around the pump body (22).

3. Displacement pump according to claim 1 or 2, character- ized in that the pump body (22) in the rotor sleeve (20) is eccentric in cross-section and an annular gap (19) between these two parts is of a gap width (t) that tapers in the circumferential direction ,

Displacement pump according to claim 3, characterized in that the inner bore of the rotor sleeve (20) is arranged eccentrically in this.

5. Displacement pump according to one of claims 1 to 4, characterized in that the cross-sectional longitudinal axis

(Q) of the longitudinal groove (24) limits an angle (w) with a diameter line (B, M) of the pump body (22).

6. positive displacement pump according to claim 5, characterized by an angle (w) of about 20 ° to 40 °, preferably about 25 °, between the cross-sectional longitudinal axis (Q) of the longitudinal groove (24) and the diameter line (B, M) of the pump body (22 ).

7. positive displacement pump according to one of claims 1 to 6, characterized by two on a diameter line (B or M) mutually opposite mutually approximately mouths (25) of longitudinal grooves (24), their mouth centers on different sides of the associated diameter line at a distance (i) to this lie (Fig. 5).

8. positive displacement pump according to claim 7, characterized in that two pairs of longitudinal grooves (24) are provided and their mouths (25) to each other on the peripheral surface (23) of the pump body (22) are offset by 90 °.

9. positive displacement pump according to one of claims 1 to 8, characterized in that in the top surface (32) of the cross-sectionally flat piston (30) has a groove-like longitudinal indentation (34) as a bearing for the bolt or formed by a bearing needle (36) needle-like body is provided.

10. Displacement pump according to claim 9, characterized in that approximately at right angles to the longitudinal indentation (34) or the top surface (32) of the flat piston

(30) run in this recesses (38) for receiving an energy accumulator (40).

11. Displacement pump according to claim 10, characterized in that the recess (38) runs next to the cross-sectional longitudinal axis (Q) of the longitudinal groove (24).

12. Displacement pump according to one of claims 1 to 11, characterized in that the flat piston (30) is supported by the spring (s) on the groove base (26) of the longitudinal groove (24) as a force accumulator (40) at a variable distance from Groove base is held.

13. Displacement pump according to one of claims 1 to 12, characterized in that the underside (31) of the flat piston (30) and the groove base (26) determine the height of a conveying or working space (28) delimited on both sides by groove walls (27).

14. Positive displacement pump according to one of claims 1 to 13, characterized in that at least one bore (46) connecting these areas is provided between the underside (31) of the flat piston (30) and its longitudinal molding (34).

15. Displacement pump according to one of claims 1 to 14, characterized in that in it the rotor sleeve

(20) has ball bearings at both ends and is closed at both ends by a pump cover (44, 44 _a ).

16. A positive displacement pump according to claim 14, characterized in that at least one valve (42) assigned to the longitudinal groove (24) is provided in the pump cover (44, 44 _a ).

17. Displacement pump according to one of claims 13 to 16, characterized in that the delivery spaces (28) in the pump cover (44, 44 _a ) are combined by connections for suction and pressure lines.

18. Displacement pump according to at least one of claims 1 to 17, characterized in that the rotor sleeve

(20) connected to a magnetic element (50) and this is part of a magnetic coupling (52).

19. Positive displacement pump according to claim 18, characterized by a counter element (51) arranged on an outer rotor (54) for the magnetic element (50).

20. Displacement pump according to claim 18 or 19, characterized in that the pot wall (58) of a can (60) is arranged in a gap (56) between the two magnetic elements (50, 51).

21. Displacement pump according to one of claims 18 to 20, characterized in that the outer rotor (54) is connected to a toothed or V-belt (64) as a drive member.

22. Displacement pump according to claim 21, characterized in that the outer rotor (54) and the toothed ^' or V-belt are replaced by a commutatorless DC stator or by a speed-controlled three-phase stator.