EP0473616A1

EP0473616A1 - Bellow-type pump with a plurality of radially arranged bellows

Info

Publication number: EP0473616A1
Application number: EP19900906886
Authority: EP
Inventors: Norbert Höhn; Hartmut Runge; Hans-Jürgen BÄNFER
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1989-05-23
Filing date: 1990-05-08
Publication date: 1992-03-11
Also published as: CA2057067A1; WO1990014517A1

Abstract

Une pompe comporte une pluralité de soufflets (51 à 54) groupés en étoile autour de l'axe d'entraînement et entraînés simultanément de sorte que le couple est appliqué uniformément. Le chargement asymétrique des soufflets, lequel réduit leur durée de vie, est évité grâce à un couplage amélioré du mouvement excentrique de l'arbre d'entraînement (34) avec les soufflets. Les sorties (62) des différents soufflets peuvent être reliées en parallèle ou en série, au choix, de manière à permettre un refoulement ou une pression de refoulement accrus, selon les besoins. Le carter de pompe (1) se compose d'une pièce en double croix servant de pièce de montage dans la technique de l'ultravide. Pour réaliser le vide complet dans la pompe, par exemple pour permettre l'introduction ultérieure de gaz ultra-purs, des soupapes à ressort (82) qui s'opposent au sens de refoulement sont maintenues temporairement en position ouverte, en service normal. A cet effet, les éléments de fermeture des soupapes sont réalisés dans un matériau magnétique et peuvent subir l'influence d'un aimant (84) monté à l'extérieur du carter de pompe (1, 73), lequel est réalisé dans un matériau non magnétique. La soupape reprend sa position fermée, dès que l'aimant (84) est amené et éventuellement arrêté dans une position éloignée.A pump comprises a plurality of bellows (51 to 54) grouped in a star around the drive axis and driven simultaneously so that the torque is applied uniformly. Asymmetric loading of the bellows, which reduces their service life, is avoided by improved coupling of the eccentric movement of the drive shaft (34) with the bellows. The outlets (62) of the various bellows can be connected in parallel or in series, as desired, so as to allow increased discharge or discharge pressure, as required. The pump housing (1) consists of a double cross piece used as a mounting piece in the ultra-vacuum technique. To achieve complete vacuum in the pump, for example to allow the subsequent introduction of ultra-pure gases, spring-loaded valves (82) which oppose the direction of delivery are temporarily kept in the open position, in normal service. For this purpose, the valve closing elements are made of a magnetic material and can be influenced by a magnet (84) mounted outside the pump housing (1, 73), which is made of a material not magnetic. The valve resumes its closed position, as soon as the magnet (84) is brought and possibly stopped in a distant position.

Description

Bellows pump with several bellows arranged in a star shape

The present invention relates to a bellows pump.

In her DE-U-87 02 659, the applicant has described an encapsulated bellows pump which can be used in particular for pumping toxic or radioactive fluids or of those whose purity is subject to increased requirements. This pump has a motor-driven shaft on which an eccentric is attached. On this in turn a piston rod is articulated, by means of which the bellows is alternately compressed and pulled apart. The arrangement of the piston rod described has the effect that the bellows is not only informed of an axial but also a transverse movement which leads to an asymmetrical compression of the bellows, as a result of which its service life can be reduced. The fact that the torque to be imparted to the shaft in the course of one revolution of the shaft is quite uneven also has an unfavorable effect.

In order to prevent possible leakages, there is no need to drive or control elements through the housing wall, so that the pumped medium is safely enclosed even if the bellows that produce the pumping action should break due to material fatigue. The housing of such a pump is preferably made of a corrosion-resistant, ie austenitic steel; this is known to be non-magnetic. Correspondingly directed check valves are installed in the supply and discharge of the pumped medium, which prevent the backflow into the suction line when the bellows are pressed together and the backflow from the pressure line when the pressure is released. These check valves can take the form of elastic metal flaps that are pressed against the valve seat in accordance with the desired direction of action as a result of their own spring properties.

If pumps of the type described are to be used for pumping high-purity gases, these must of course be reliably evacuated before being put into operation in order to prevent contamination of the gases with air components. This evacuation is now hindered by the action of the valves described: even in the case of an evacuation via the pressure line, the valve installed in the latter becomes at the end of the evacuation process if there is only a slight pressure difference between the interior of the housing and the suction chamber of the vacuum pump. return to its closed position prematurely.

The object of the present invention is to provide a bellows pump in which the disadvantages described are avoided and which moreover has increased performance with only insignificantly enlarged dimensions. Furthermore, the pump should be able to be adapted to changing requirements with regard to the delivery pressure and the delivery rate. A further object of the present invention is a valve control which allows the valves, in particular that in the pressure line when the pump is at a standstill, to be kept open without giving up the integrity of the housing even when there is no significant pressure drop from the inside to the outside via the valve seat more exists.

This object is achieved in that the bellows pump several star-shaped around a common, in a known manner provided with an eccentric drive shaft arranged and actuated by means of separate, attached to the eccentric piston rods, and provided with separate inlets and outlets for the pumped fluid bellows having. Furthermore, in that the housing from a non-magnetic, the closing body of the valves, however, from a magnetic material and the latter are evident by magnets attached to the outside of the housing. With relatively small magnets, the desired forces on the closing body of the valve, for. B. be exercised on one of the metal tongues mentioned.

With regard to an inexpensive form of the housing of such a pump, which is explained in more detail below, a number of four bellows, each offset by 90 ° from one another, seems particularly suitable. Since each of these bellows is in a different stage of contraction or expansion, the torque to be applied by the drive is largely equalized. Both this drive and the housing containing the pump need only be insignificantly reinforced or enlarged compared to the "single-cylinder" pump described above.

In an embodiment of the pump according to the invention, the outlets for the pumped fluid can be connected in series, which leads to a corresponding increase in the delivery pressure to a multiple (n = number of bellows).

In an alternative embodiment of this, the outlets for the pumped fluid can be connected in parallel next to one another, with which a corresponding multiplication of the delivery volume is achieved while the delivery pressure remains constant. It is within the scope of the invention if the pump is designed in such a way that these two circuit options can be implemented alternately at will.

Contrary to the previously common construction as stated above, it is proposed in a further embodiment of the invention that the individual piston rods can be pivoted on the bellows, on

Eccentrics, however, are rigidly attached. This ensures that the bellows are practically operated only in the axial direction and no more asymmetrical compression occurs.

Another improvement according to the invention of the pump described is that the length of the piston rods can be changed. As a result, the achievable delivery pressure can be varied within certain limits by changing the ratio of the bellows compressed to a more or less large residual volume to that of the expanded bellows. This also facilitates the possibility of precise adjustment of the individual bellows in order to achieve a uniform delivery pressure.

According to a further embodiment of the invention, the bellows pump is arranged in a housing which consists of a double cross piece known per se in ultra-high vacuum technology. In such a piece, which is relatively inexpensive as a finished part on the market, a particularly favorable arrangement of the various pump parts can be realized, as explained in more detail below with reference to the description of an exemplary embodiment.

In a further embodiment of the invention, the magnets have the shape of ring magnets arranged to be longitudinally displaceable on the lines. In this way, the exact guidance of the magnets is ensured in a simple manner, namely from a first position in which they do not influence the valves to a second position to be determined constructively in which they open the valve in question.

The first position will usually be some distance from the pump housing. Therefore, a further embodiment of the invention is characterized in that the magnets can be locked in a position remote from the valves, in which they 1 remain as long as the valves are not at one

Evacuation process or must be operated separately for other reasons.

According to the further embodiment of the invention, the magnets are magnetized in the axial direction to their maximum

* Effective force also to develop in the axial direction where the valves are at the moment.

10 An embodiment of the invention is shown in the drawing, namely shows

Figure 1 is a perspective view of the pump without its

Drive,

Figure 2 shows a longitudinal axial section through the same, the 15 Figures 3 and 4 circuit diagrams for their inlets and outlets and

Figure 5 on an enlarged scale the detail V of FIG. 2 with additional devices.

The pump is arranged in a housing 1, as it is

20 so-called double cross piece on page 11.8 of the catalog HV 200 from Leybold AG from November 1987 is described. This shape essentially results from a central, spherical part 10, four connecting pieces 11 to 14 formed thereon at right angles to one another and two further connecting pieces 15, 16,

25 which are arranged perpendicular to the plane of the nozzle 11 to 14. Each of these sockets 11 to 16 has at its end a flange 21 to 26, via which the double cross piece can be connected to subsequent pipelines, not shown here, etc.

30

On the flange 25, a drive unit 30 (not visible in FIG. 1) is attached, which u. a. (see Figure 2) consists of an electric motor 31 of the required power, by means of which the first magnets 32 are set in rotation. This

35 take along second magnets 33 which are fastened on a drive shaft 34 and which are fluid-tight from the first magnets 32 separated by a hood 39 (which in turn forms part of the housing 1); this makes it possible to replace the motor 31 if necessary without having to open the interior of the pump housing 1. An eccentric inner ring 35 is fastened on the drive shaft 34 in the center of the spherical housing part 10, on which an eccentric outer ring 37 can be rotated, separated by ball bearings 36. Piston rods 41 to 44 (42 and 44 not visible here) are evenly distributed over its circumference and are screwed more or less deeply into corresponding threads 38 in the eccentric outer ring 37 and fixed in the desired position by nuts 40. At its outer end, the piston rods 41 to 44 are attached to corresponding bellows 51 to 54 (52 and 54 not visible here), which are alternately compressed and pulled apart when the drive shaft 34 rotates. The piston rods 41 to 44 are with sliders 46-49 (47 and 48 not visible here), in guides 91 to 94 (92 and 94 not visible here), which are fixed in relation to the housing 1; this ensures that the bellows 51 to 54 are only axially loaded and cannot buckle laterally under this load. Through inlets and outlets 61, 62, which have check valves 81; shown in FIG. 5 and which block in opposite directions; 82 are provided, the fluid to be pumped is sucked in or expelled again. The one or. Outlets 61, 62 are mounted in end covers 71 to 74 (72 and 74 not visible here), which are fastened to the flanges 21 to 24 with screws 70. While the flange 25 is used to fasten the drive unit 30, the flange 26 which is not required here is closed with a blind cover 76.

FIG. 3 shows a series connection of the pump and FIG. 4 shows a parallel connection, the same reference symbols being used in both diagrams. The bellows 51 to 54 actuated by the drive shaft 34 each convey via inlets 61 and outlets 62. A common main inlet line is 65 and a common one Main outlet line labeled 66. In the representation of the

Figure 3 leads the main inlet line 65 first to the inlet 61 of the bellows 54, through the outlet 62 into the inlet 61 of the bellows 53, from the outlet 62 in turn in the

Inlet 61 of the bellows 52 and from its outlet 62 in turn into the inlet 61 of the bellows 51. From the outlet 62, the main outlet conduit 66 finally begins. In this one prevails over the delivery pressure of each individual

Bellows to four times the pressure with the same delivery rate.

In the representation of Figure 4 lead from the

Main inlet line 65 stub lines to each of the inlet valves 61 of the individual bellows 51 to 54. From their outlet valves 62, in turn, stub lines lead to the common main outlet line 66, in which finally, with unchanged pressure, a flow rate increased four times compared to the performance of a single bellows.

Each inlet 61 can be shut off by a first valve 81 and each outlet 62 by a second valve 82. Both valves are in the form of reed valves, are made of a magnetic, resilient material and are directed in such a way that the first valve 81 leads the way inside of the bellows 4 releases when it is stretched, ie its volume increases. At the same time, the second valve 82 is pressed against its seat and closes the outlet 62. When the bellows movement is reversed, the first valve 81 springs back into its seat and the second valve 82 gives in to the pump pressure and opens the outlet 62. If the interior of the housing 1 are evacuated in order to remove air residues which would contaminate the ultrapure gas to be pumped therewith (e.g. helium), a vacuum pump 83, which is only schematically indicated here, is expediently connected to the outlet 62. A really sufficient evacuation can only take place if the second valve remains open. This is done by the effect of a ring magnet 84 which is arranged on the outlet 62 to be longitudinally displaceable. In its position shown on the end cover 73, its field lines act through the latter on the second valve 82 and hold it in its open position. In normal operation of the pump, the ring magnet 84 assumes the position indicated by the broken line, in which it is held by any lock 85. In this position, no significant magnetic forces act on the second valve 82.

Claims

1. Bellows pump, characterized in that it several star-shaped around a common, in a conventional manner with an eccentric (35) to (37) provided drive shaft (34) arranged and actuated by means of separate piston rods (41) to (44) attached to the eccentric , and with separate inlets and outlets (61, 62) for the pumped fluid provided bellows (51) to (54).

2. Bellows pump according to claim 1, so that the outlets (61, 62) for the pumped fluid can be connected in series in series.

3. Bellows pump according to claim 1, so that the outlets (61, 62) for the pumped fluid can be connected in parallel next to one another.

4. Bellows pump according to claim 1, 2 or 3, characterized in that the individual piston rods (41) to (44) on the respective bellows (51) to (54) pivotally (50), but rigidly attached to the eccentric (38, 40) .

5. Bellows pump according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the length of the piston rods (41) to (44) is variable.

6. Bellows pump according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that it is arranged in a housing (1) which consists of a double cross piece known per se in ultra-high vacuum technology.

7. bellows pump according to one or more of the preceding claims with emerging from a fluid-tight housing (1), by check valves (20, 21) against a backflow of the pumped medium, shut-off suction (18) or pressure lines (19), the valves being pressed into their closed position by spring pressure, characterized in that the housing (1) consists of a non-magnetic, the Closing bodies of the valves (20, 21), on the other hand, are made of a magnetic material and the latter are evident by magnets (23) movably attached to the outside of the housing.

8. Bellows pump according to claim 7, d a d u r c h g e k e n n z e i c h n e t that the magnets (23) have the shape of ring magnets arranged longitudinally displaceably on the lines (18, 19).

9. bellows pump according to claim 8, d a d u r c h g e k e n n z e i c h n e t that the magnets (23) in a position remote from the valves can be determined (24).

10. Bellows pump according to claim 8 or 9, d a d u r c h g e k e n n z e i c h n e t that the magnets (23) are magnetized in the axial direction.