EP1299643B1 - Positive displacement pump - Google Patents

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

The invention relates to a positive displacement pump according to the preamble of the independent claim.

Piston engines offer a periodically gestartveränderlichen Working space, which filled with a fluid medium is; its pressure changes during compression rising, falling during an expansion. The essential geometric size is the stroke volume as that of the displacer effected change of the working space during a stroke.

For piston pumps - so-called oscillating positive displacement pumps a piston in a closed displacement chamber the displacer volume via pressure-dependent opening elements against a system pressure. The theoretical funding work is calculated from the stroke volume and the differential pressure of Saugzur Pressure side formed, the stroke volume ensteht by the Movement of the piston between a lower and an upper Dead center. The movement is mostly through transformation a rotational movement of the drive unit via a "crank" transformed into a reciprocating motion; the constant Rotary movement of the drive is in a non-constant Stroke movement of the pump piston converted. this has Result that the fluid to be delivered with a relative high change of flow rate - oscillating Flow - is moved in the displacement of the pump. These so-called pulsation of the flow is determined by a measurement of Pressure pulsation detectable. The resulting possibly Disadvantages are known.

Generally, the drive of such pumps takes place in the classic Aggregate construction, i. Pump and motor are on one Base plate or a lantern in alignment both Shaft axes through a coupling, the necessary drive power connected transmitting element. An exception forms the direct clutch of the engine; Here is the pump shaft on the drive side designed as a hollow shaft such that the motor shaft is inserted and then a torque can transfer.

Other exceptions are the so-called hermetically sealed pump superstructures. This must be because of toxic, aggressive or flammable liquids to any kind of leakage the shaft seal of the exiting pump shaft avoided become. This is done either by Zwischeneinbau known Magnetic couplings between pump shaft and aggregate coupling, or by the tight connection of the motor housing with the pump housing by means of a hermetic seal between stator and rotor of the motor in so-called "canned engine" design. Such hermetically sealed pumps are extremely expensive. With the magnetic coupling Add to that any slip between outside and outside Inner rotor due to large safety surcharges in the design must be avoided, since no restart after one short-term slip between the two rotors is possible.

The generic GB 255 873 A offers a vane pump at which the space between adjacent pistons is used as a pumping room. The latter is through the room formed between successive wings.

Bushings are disclosed in US 5,769,611 A and US 1,526,343 known with eccentric inner bore. there are radial piston pumps with cylindrical Piston.

DE 1 107 084 B is a radial piston pump with a -with connected to the pump shaft - bell-shaped pump rotor to be taken, the one receiving the piston - on fixed - comprising pump body; the pump rotor is configured to an inwardly directed cam track, in the radial direction one of the piston number corresponding number of round corners containing the lift curves for simultaneous and same-minded operation of all pistons.

In knowledge of this prior art, the inventor set the goal, an always hermetically sealed pump without elaborate pump / motor design represent.

To solve this problem, the doctrine leads to the independent Patent claim; the dependent claims give favorable Further education. In addition, fall within the scope of the invention all combinations of at least two of those in the description, the drawing and / or the claims revealed Characteristics.

According to the invention, the pump body is - in particular oscillating - positive displacement pump with the in it with Provided energy storage associated flat piston Longitudinal grooves in a rotatable about the pump body Rotor bushing stored as well as each flat piston at its for Rotor sleeve pointing head surface a bolt or needle-like body associated, on the outer surface of the Inner surface of the rotor sleeve rests; those flat-bottomed pistons determined together with the surrounding longitudinal groove the Conveying or working space.

According to a further feature of the invention, the pump body extends in the rotor bush cross-sectionally eccentric; in a particularly favorable embodiment, the inner bore the rotor bushing arranged eccentrically in this. In In any case, there is one between these two parts Annular gap before tapering in the circumferential direction Gap width.

So instead of the rotor shaft of the classic drive the rotor bush with eccentrically arranged inner bore used. Inside this eccentric inner bore is the pump body with two or more - radially and circumferentially arranged evenly distributed - centric longitudinal grooves arranged to the fulcrum of the drive motor so that the in the longitudinal grooves inserted piston by the circumferential eccentric bore of the rotor sleeve to a lifting movement are forced.

Advantageously, the longitudinal grooves in the pump body mounted cross-sectionally inclined to the diameter straight line; limited the cross-sectional longitudinal axis of the longitudinal groove with one of the diameter lines of the pump body a Angle of about 20 ° to 40 °, in particular of about 25 °.

A preferred positive displacement pump is characterized by two Pairs of longitudinal grooves whose mouths to each other at the Circumferential surface of the pump body offset by 90 ° are; because in each case two such longitudinal grooves are on one Diameter line with each other at about the opposite side Associated with estuaries, according to the invention their Muzzle centers on different sides of the assigned Straight diameters lie at a distance to this, that is are offsets. Of course, the invention to the described embodiment with two pairs of Longitudinal grooves not limited; it can also be a larger number be provided for such pairings.

As low, it has been proven in the head area of the cross-sectionally flat piston a trough-like Längseinformung as a bearing for the one formed by a bearing needle to provide bolt or needle-like body; at a right angle to the longitudinal indentation or the top surface of the flat piston are supposed to record in each of these recesses an energy store run. Each of these recesses is preferably adjacent to the cross-sectional longitudinal axis the longitudinal groove; The purpose of this offset is the stock pressure side First surface Mehrung. Thanks to the groove bottom of the Längsnut supporting, designed as a helical spring Force accumulator is the flat piston at a variable distance held to the groove bottom. The energy store provides the playless fixing of the piston via the head needle bearings for eccentric rotor rifle safe.

In the context of the invention, the underside of the flat piston determine and the bottom of the groove is the height of either side of Grooved walls limited conveyor or work space. This should be replaced by at least one between the bottom of the Flat piston and its longitudinal recess provided hole be connected to the needle roller bearing.

According to the rotor bush in the positive displacement pump ball-bearing at both ends and a pump cover at both ends locked. These are arranged to the right and left of the pump body Pump caps according to the invention have corresponding Valves, to prevent the lifting movement of each flat-bottomed piston a conveying process of the pumped medium from the suction to To produce pressure side of the pump according to the invention. The individual production rooms or subsidy chambers - equal to each one Selected number of flat pistons - are in the Pump covers summarized and form over the engine cover the connections for the suction and pressure line.

It is within the scope of the invention that these constructive Available in both DC and AC motor versions can be represented.

In addition, it has proved favorable that by appropriate Material choice both lubricating and hardly Lubricating fluids can be pumped. The constructive Execution always provides an "inline version" according to the pump standards, wherein any "Aggregate structure" is eliminated.

According to a further feature of the invention is characterized by the Choice of the number of flatbulbs and the choice of a relative wide range of modified strokes - changing the eccentricity the inner bore of the rotor bushing - at a "Size" the delivery quantities "quantity" and "pressure" in one wide range changed.

A particular advantage over conventional positive displacement pumps is an improved security against "seizure" the conveying elements, as in the lubrication gap between the pump body and flat piston always the delivery pressure on both sides degrades, the pressure component from the delivery chamber not in the direction of the sliding bearing surfaces acts, as for example in a screw pump is the case. In the subject of the present invention increases with increasing tangential force on the flat pistons the increase in the transmitted torque of the rotor bushing - at increasing discharge pressure to the same extent also the hydrostatic Pressure in the lubrication gap.

The classic construction of the rotor of a three-phase motor consists known from the laminated core of the squirrel cage a drive shaft with the cast-cage grooves as Squirrel-cage rotor. Now replace the drive shaft - in The necessary minimum dimensions of the cage bars - through the rotor bushing according to the invention and changes the Motor housing cover in the described manner, then forms this results in the complete motor / pump / unit. at Such a design eliminates any shaft seal, commonly referred to as the weakest link in pumps with emergent Shaft end is known. At the same time you reach without further addition the "hermetically sealed" pump a cost that is about that of a simple one Aggregate structure corresponds. The usually necessary Alignment of motor and pump in classical aggregate construction, to ensure proper functioning of the intermediate Secure coupling, is omitted in the present Invention likewise.

At a required speed control of this pump and / or in applications of higher speeds is the - mentioned - Design as a DC or single-phase machine also possible; In this case, the rotor winding through a package of permanent magnets - known from the magnetic couplings - replaced. This allows for low Designs (here the system diameter) and opened a wide field of application of mass production of Small pumps with high pressure ranges.

In any case, only the suction pressure of the Pumped medium, since the leakages occurring both from the Playing the flat piston in the pump body as well as those the needle bearing by a connection to the suction of the Pump be discharged.

Instead of the usual drive systems with direct current, AC or AC has become the use of a Magnetic coupling proved to be particularly favorable, with an internal magnetic element, already discussed Rotor can face an outer rotor, the one carries corresponding magnetic counter element; the two Magnetic elements form a magnetic coupling; through the Use of a hermetically sealed magnetic coupling during Subject of the invention the two transmitting the moment and equipped with magnets rotors by means of canned sealed.

The drive takes place by means of a on that outer rotor engaging toothed or V-belt. This is the result Possible use as flanged auxiliary unit at Power machines of all kinds allows. If you replace the Magnets having outer rotor together with the tooth or V-belt elements e.g. through a DC or commutatorless three-phase stator, is the application of to recognize above generally described pump; because of the sizing is especially the application given this pump in mobile use.

Fig. 1:

eine teilweise geschnittene Stirnansicht einer Tangentialkolbenpumpe;

Fig. 2:

eine teilweise geschnittene Seitenansicht der Tangentialkolbenpumpe als Gleichstrommaschine;

Fig. 3:

eine teilweise geschnittene Seitenansicht der Tangentialkolbenpumpe als Drehstromkurzschlussläufermaschine;

Fig. 4:

den gegenüber Fig. 3 vergrößerten Längsschnitt durch die Tangentialkolbenpumpe;

Fig. 5:

einen vergrößerten Querschnitt durch einen zentralen Teil der Fig. 1 und deren Schnittlinie V - V;

Fig. 6:

einen Ausschnitt aus Fig. 5;

Fig. 7, 8:

eine teilweise geschnittene Stirnansicht sowie eine gleichermaßen teilweise geschnittene Stirnansicht einer anderen Ausgestaltung einer Pumpe.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; this shows in

Fig. 1:

a partially sectioned end view of a tangential piston pump;

Fig. 2:

a partially sectioned side view of the tangential piston pump as a DC machine;

3:

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

4:

compared to Figure 3 enlarged longitudinal section through the tangential piston pump.

Fig. 5:

an enlarged cross-section through a central part of Figure 1 and the section line V - V;

Fig. 6:

a detail of Fig. 5;

Fig. 7, 8:

a partially sectioned end view and an equally partially cut end view of another embodiment of a pump.

In a tangential piston pump 10 is in one - at both ends from mounting strips 12 having housing covers 14th closed - tubular housing 16 in the range of Ball bearings 18 a rotor bushing 20 of the inner diameter d mounted, which has a pump body 22 of circular cross-section surrounds the diameter e.

The longitudinal axis of the pump body 22 is designated A, and in it are four longitudinal grooves 24 with cross-section part-circularly rounded groove base 26 arranged such that in the example shown their cross-sectional longitudinal axes Q with the - a diameter straight determining - cross-sectional central axis M or the perpendicular to this Transverse axis B of the pump body 22 an angle w of about Limit 25 °. The center of the mouth 25 of the longitudinal grooves 24th on the body circumference is shown in FIG. 5 by a measure i to the corresponding cross-sectional central axis M and the transverse axis B offsets, and the cross-sectional longitudinal axes Q of the two longitudinal grooves 24 on the cross-sectional central axis M. run as parallel to each other as the Cross-sectional longitudinal axes Q of the two of the transverse axis B assigned Longitudinal grooves 24.

Each longitudinal groove 24 of the cross-sectional width a takes a Flat piston 30, in the outwardly directed head surface 32 in a running in the longitudinal direction indentation 34 - the width b of its part-circular cross-section - A bearing needle 36 rests; on one side of the cross-section in a measure 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 eccentric in the flat piston 30 extending longitudinal indentation 34 is the wider strip of the top surface 32 too a panel surface 33 of width f bevelled. When turning the rotor sleeve 20 is formed by the contact of the latter Inner surface 21 and the surface of the peripheral surface 23rd the pump body 22 cross-section partially superior Bearing needles 36 a rolling movement as in a needle bearing.

Is - as illustrated in Fig. 5 - the inner diameter d the rotor sleeve 20 eccentric to the outer diameter e of Arranged pump body 22, so arises between that Peripheral surface 23 and the inner surface 21 of the rotor sleeve 20th cross-sectionally an annular gap 19 with it - in Fig. 5-down tapering gap width t as well as upon rotation, i. when unrolling the rotor bushing 20 on the bearing needles 36, a reciprocating movement of the flat piston 30 with a stroke, which is the double eccentricity of the inner diameter d of the rotor sleeve 20 corresponds.

When stroke of the flat piston 30 in the pump body 22 against a - provided in an eccentric to the cross-sectional longitudinal axis Q and parallel to this in flat piston 30 recess 38 - energy storage 40 is a volume in one of the Nutenwänden 27 laterally limited delivery chamber 28 between the piston bottom 31 and Groove bottom 26 compressed. By appropriate arrangement of valves 42 in suction and pressure side pump covers 44, 44 _a on the end faces of the pump body 22 can be performed by the lifting movement of the flat piston 30 a conveying work. This theoretical yield generated in this way corresponds in its size (.DELTA.Q / .DELTA.t or generally in 1 / min) in linear dependence: "Q theor. "= Number of pistons * piston area * stroke * speed.

By the choice of a flat piston 30 is for the representation the delivery volume - with appropriate choice of the number of pistons - a minimum stroke is sufficient. For a series in a conveying range of for example 40 to 1400 1 / min and a speed of 2950 min ^ -1 moves the maximum stroke in the range of 2 to 6.5 mm. That has to Result that the known disadvantages of oscillating positive displacement pumps in terms of the pulsating flow a minimum can be reduced. With more than one Flat piston 30 is thus also the forming pressure pulsation at the discharge nozzle of the pump 10 is far reduced.

The piston movement during the suction stroke, i. the wake of the Flat piston 30 in the range of diameter enlargement or the positive eccentricity of the inner diameter d of the rotor bush 20 takes place by the biasing force of in the Recesses 38 of the flat piston 30 inserted springs as energy storage 40, the lubrication of the needle bearing on Piston head 32 of the flat piston 30 through the fluid by means of arrangement of holes 46 or the like. Compounds of in the longitudinal groove 24 remaining delivery chamber 28 with the Lagerausnehmung or longitudinal recess 34 in the piston head 32nd Over a wide range of lubricating properties of the fluid (Also v ≤ 1 mm ^ 2 / sec.) Can by appropriate Choice of material and surface of the needle roller bearings one hydrostatic lubrication be maintained, as well Here, the lubrication pressure always increases with the delivery pressure.

In the embodiment described above is a seal of the motor stator with respect to the pumped medium executed. If required, the stator receives as in the known "canned motor" a thin-walled tube from the classic materials of this application. For aggressive Media - e.g. in chemistry - because of the negligible lubrication limit due to the missing Slide bearing conditions by appropriate choice of material Pump body parts and the flat piston a wide range be covered.

Because with this construction no classical fan on the Motor shaft can be arranged, is the stator housing to be provided with appropriate surface cooling. In each Case, however, will be a certain amount of magnetic Waste heat once through the circulation of the leakage currents, which flow through the bearings on the stator to the suction side, and on the other by the heat conduction squirrel cage / rotor bushing added.

Instead of drive systems with DC, AC or three-phase current, the rotor sleeve 20 can also be driven by a magnetic coupling. For this purpose, the rotor bushing 20 of the tangential piston pump 10 _a according to Fig. 7, 8 at its axially parallel outer contour at least a sleeve-like magnetic element 50. Between this and a magnetic counter-element 51 of an outer rotor 54 extends in a direction parallel to the longitudinal axis A gap 56 - the inner magnetic element 50th hermetically sealing pot wall 58 of a split pot 60 surrounded by that outer rotor 54. The latter is associated with a support ring 62 endwise.

The outer rotor 54 at the of the magnetic elements 50, 51 Magnetic coupling 52 is formed by a dental or V-belt 64 driven.

In this pump 10 _a , the drive torque - coming from an outer shaft - via the particular, the two rotors 20, 54 detected magnetic coupling 52 is supplied to the inner pump body 22.

Claims (20)

1. Positive displacement pump (10, 10_a) having arranged in a pump housing (16) a pump member (22) for pistons (30) mounted relatively movably in the latter in longitudinal grooves (24) emanating from the circumferential surface (23) of the pump member (22) to change the shape of an operating chamber (28),
   characterised in that
   the pump member (22) of the especially oscillating positive displacement pump (10, 10_a) is seated with the longitudinal grooves (24) in it provided with flat-topped pistons (30) associated with energy stores (40) in a rotor sleeve (20) which is rotatable about the pump member (22) and assigned to each flat-topped piston (30) on its head surface (32) pointing to the rotor sleeve (20) is a bolt-like or needle-like member (36) against whose outer surface the inner surface (21) of the rotor sleeve (20) rests, wherein the flat-topped piston (30) and the longitudinal groove (24) determine the conveying or operating chamber.
2. Positive displacement pump according to claim 1, characterised in that the lower end (31) of the flat-topped piston (30) and the base (26) of the groove determined the height of the conveying or operating chamber (28) bounded on both sides by groove walls (27).
3. Positive displacement pump according to claim 1 or 2, characterised in that the flat-topped piston (30) is held at a variable spacing relative to the base of the groove by the spring(s) as energy store(s) (40) braced against the base (26) of the longitudinal groove (24).
4. Positive displacement pump according to one of claims 1 to 3, characterised in that the pump member (22) runs eccentrically in cross-section in the rotor sleeve (20) and an annular gap (19) present between these two parts has a gap width (t) which tapers in the circumferential direction.
5. Positive displacement pump according to claim 4, characterised in that the inner bore of the rotor sleeve (20) is arranged eccentrically in the latter.
6. Positive displacement pump according to one of claims 1 to 5, characterised in that in the head surface (32) of the piston (30) of flat cross-section a channel-like longitudinal depression (34) is provided as a bearing for the bolt-like or needle-like member formed by a bearing needle (36).
7. Positive displacement pump according to claim 6, characterised in that at approximately right angles to the longitudinal depression (34) or the head surface (32) of the flat-topped piston (30), running in the latter are recesses (38) for accommodating in each case an energy store (40), wherein the recess (38) preferably runs beside the cross-sectional longitudinal axis (Q) of the longitudinal groove (24).
8. Positive displacement pump according to one of claims 1 to 7, characterised in that between the lower end (31) of the flat-topped piston (30) and the longitudinal depression (34) thereof at least one bore (46) connecting these regions is provided.
9. Positive displacement pump according to one of claims 1 to 8, characterised in that the cross-sectional longitudinal axis (Q) of the longitudinal groove (24) bounds an angle (w) with a diametrical straight line (B, M) of the pump member (22).
10. Positive displacement pump according to claim 9, characterised by an angle (w) of approximately 20° to 40°, preferably approximately 25°, between the cross-sectional longitudinal axis (Q) of the longitudinal axis (24) and the diametrical straight line (B, M) of the pump member (22).
11. Positive displacement pump according to one of claims 1 to 10, characterised by two outlets (25) of longitudinal grooves (24) approximately opposite one another at both ends of a diametrical straight line (B or M), wherein the outlet centres thereof are located at different ends of the associated diametrical straight line at a distance (i) from the latter.
12. Positive displacement pump according to claim 11, characterised in that two pairs of longitudinal grooves (24) are provided and the outlets (25) thereof are offset relative to one another on the circumferential surface (23) of the pump member (22) by 90° in each case.
13. Positive displacement pump according to one of claims 1 to 12, characterised in that within it the rotor sleeve (20) is mounted on ball bearings at both ends and closed at both ends by a pump cover (44, 44_a).
14. Positive displacement pump according to claim 13, characterised in that in the pump cover (44, 44_a) at least one valve (42) assigned to the longitudinal groove (24) is provided.
15. Positive displacement pump according to one of claims 1 to 14, characterised in that the conveying chambers (28) are united in the pump covers (44, 44_a) by means of connectors for suction and pressure lines.
16. Positive displacement pump according to one of claim 1 to 15, characterised in that the rotor sleeve (20) is connected to a magnetic element (50) and this is part of a magnetic coupling (52).
17. Positive displacement pump according to claim 16, characterised by a counterpart element (51) for the magnetic element (50) arranged on an external rotor (54).
18. Positive displacement pump according to claim 16 or 17, characterised in that in a gap (56) between the two magnetic elements (50, 51) the pot wall (58) of a dividing pot (60) is arranged.
19. Positive displacement pump according to one of claims 16 to 18, characterised in that the external rotor (54) is connected to a toothed belt or a V-belt (64) as drive element.
20. Positive displacement pump according to claim 19, characterised in that the external rotor (54) and the toothed belt or V-belt are replaced by a dc stator without commutator or by a speed-controlled three-phase stator.

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