EP0084084B1 - Oil-sealed vacuum pump - Google Patents

Oil-sealed vacuum pump Download PDF

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Publication number
EP0084084B1
EP0084084B1 EP82109588A EP82109588A EP0084084B1 EP 0084084 B1 EP0084084 B1 EP 0084084B1 EP 82109588 A EP82109588 A EP 82109588A EP 82109588 A EP82109588 A EP 82109588A EP 0084084 B1 EP0084084 B1 EP 0084084B1
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EP
European Patent Office
Prior art keywords
oil
pump
line
pressure
vacuum pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP82109588A
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German (de)
French (fr)
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EP0084084A1 (en
Inventor
Hanns-Peter Dr. Berges
Peter Frieden
Wolfgang Leier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Balzers und Leybold Deutschland Holding AG
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Leybold Heraeus GmbH
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Publication of EP0084084A1 publication Critical patent/EP0084084A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
    • F04C27/02—Liquid sealing for high-vacuum pumps or for compressors

Definitions

  • the invention relates to an oil-sealed vacuum pump with an oil circuit for supplying the bearings and the pump chamber with oil and an oil circuit valve for shutting off the oil supply to the pump chamber when the pump is at a standstill.
  • An oil-sealed vacuum pump of this type is known from G B-PS No. 875444.
  • the oil pump in the oil circuit sucks the oil from the oil supply in the pump housing and conveys it to a kind of non-return valve, the closing piece of which is under the action of a very weak spring, so that the oil pressure in the oil circuit is only slightly above the ambient pressure. From the valve, which opens against the spring pressure, the excess oil pumped by the oil pump reaches the pump chamber via the bearing of the pump shaft and from there is returned to the oil reservoir via the outlet valve.
  • the disadvantage of this is that no oil can be supplied to the bearings with a pressure that is significantly above the ambient pressure, which is desirable for safe and continuous bearing lubrication.
  • the present invention has for its object to provide an oil-sealed vacuum pump of the type mentioned, in which, despite safe bearing lubrication with pressure oil, pump operation of up to 1000 mbar suction pressure is ensured without unnecessarily loading the pumped gases with oil vapors.
  • the oil circuit serving to supply the bearings of the pump chamber with oil has a pressure stage for reducing the overpressure generated by the oil pump to the ambient pressure and that the branches leading to the bearings - based on the direction of the flowing oil - upstream of the pressure stage and the branch line leading to the pump chamber as well as the shut-off valve behind the pressure stage.
  • the oil pump and the pressure stage can be used to maintain a relatively high pressure in the first part of the oil circuit, from which the bearings are supplied with lubricating oil.
  • the pump room is supplied with pressure-relieved oil, so that the pump works as a self-priming pump.
  • Such a pump sucks little oil at high suction pressures, and a lot of oil at end pressure operation.
  • the increased oil consumption and the disturbing environmental impact at high intake pressures are therefore greatly reduced.
  • the oil supply to the bearings from an oil circuit with a relatively high pressure enables an oil filter to be switched on in this part of the oil line, via which a relatively high pressure difference drops, so that only cleaned oil can be supplied to the bearings. It is also possible to monitor the pump via the oil pressure, which allows a clear statement about the operating state of the pump.
  • the supply of oil to the pump chamber from the subsequent pressure-relieved part of the oil circuit has the advantage that only cleaned oil gets into the pump chamber.
  • the shut-off valve ensures that when the pump is switched off, the amount of oil that remains within the pump chamber is reliably limited. This gives decisive advantages when the pump is cold started, which has a direct influence on the dimensioning of the motor of the pump. An undesirable increase in oil in the pump and in the suction port when the pump is accidentally reversed is also reliably prevented.
  • the oil circuit of the pump is formed by the suction line 11, via which oil is conveyed from the oil reservoir 2 into the oil pressure line 13 by means of the oil pump 12.
  • a throttle 15 is arranged, which ensures the maintenance of the desired oil pressure (between 1.5 and 2, preferably 1.7 bar) and via which the pressure is reduced to the pressure in the oil box 1 .
  • the bearings in the pump are supplied with pressure oil via branches 16, 17, 18.
  • Three oil supply lines 16, 17, 18 are required in the case of a two-stage pump This means that two repositories and one intermediate bearing of the two rotors have to be supplied with oil. In the case of a single-stage pump, two of the three branch lines are sufficient. After flowing through the bearings, the oil that has entered the branch lines 16, 17, 18 returns to the oil reservoir 2.
  • An oil filter 19 is switched into the pressure oil line 13 immediately behind the oil pump 12, so that it is ensured that only cleaned oil flows through the line 13 and through the branch lines connected to it.
  • Another branch line 21 opens into the control cylinder 22, in which the control piston 23 is located.
  • the pressure medium line 24 opens into the cylinder 22, the other end of which is connected to the cylinder 9 on the side of the piston 8 facing away from the valve plate 7.
  • the inlet opening 25 of the pressure medium line 24 in the cylinder 22 is designed as a valve seat.
  • a plug 26 with a sealing bead 27 is inserted into the inlet opening 25.
  • the end face 28 of a cylindrical projection 29 on the control piston 23 with a reduced diameter compared to the control piston serves as the closure member.
  • the control piston 23 is under the action of a spring 31, which is arranged between the control piston 23 and the end wall 32 with the inlet opening 25 of the pressure medium line 24 and is designed as a compression spring.
  • the cylindrical extension 29 can be screwed into the control piston 23 by means of the thread 33, so that the force of the spring 31 acting in the closed state of the control valve 27, 28 can be influenced.
  • a further line 34 opens into the cylinder 22 and is connected to an oil reservoir 35 of small volume which is open at the top.
  • the junction of the line 34 in the cylinder 22 lies on the side of the control piston 23 opposite the junction of the line 21.
  • the oil pump 12 conveys oil from the oil supply 2 into the oil pressure line 13.
  • the oil pump 12 can be designed as a rotary vane pump or gear pump and is coupled in a known manner to the pump shaft as a drive (cf. GB-PS No. 875444).
  • the delivery properties of the pump 12 and the size of the throttle 15 are dimensioned such that the desired oil pressure is built up and maintained in the line 13 after the vacuum pump has started. This pressure acts on the piston 23 and overcomes the force of the spring 31, so that the inlet opening 25 of the pressure medium line 24 is closed.
  • the suction nozzle valve 4 is in its open position, so that the recipient connected to the suction nozzle 3 is evacuated.
  • the pump is switched off, the amount of oil delivered by the oil pump 12 decreases at the same time, so that the oil pressure in the line 13 decreases.
  • the inlet opening 25 is opened so that owing to the atmospheric pressure prevailing on the surface of the oil in the oil reservoir 35, oil is pressed into the pressure medium line 24 and reaches the cylinder 9 under the piston 8.
  • the amount of oil located below the piston 23 and in the oil reservoir 35 is so small that the oil entering the cylinder 9 essentially serves only to seal the piston 8 against its cylinder wall.
  • the actual pressure medium for actuating the piston 8 is the air which, following the oil, passes through the oil supply 35 into the pressure medium line 24.
  • the total amount of oil in the cylinder 22 and in the oil reservoir 35 is a few cubic centimeters. It should be so small that it essentially serves only to seal the gap existing between the piston 8 and the cylinder 9. These processes cause the suction nozzle valve 4 to close without the undesirable air intake. After the suction port valve 4 is closed and the urging air has displaced the oil between the piston 8 and the cylinder wall 9, the pump chamber is ventilated.
  • the function of the intake valve control is independent of the existence of an oil filter 19, i.e. Even in an oil circuit without an oil filter 19 (see line section 20 shown in broken lines), the suction nozzle valve and its control means work perfectly.
  • a particular advantage of the described embodiment of the suction nozzle valve 4 and its control means that work as a function of the oil pressure is that both cylinder / piston devices 8, 9 and 22, 23 are hardly susceptible to tolerances because of the desired gap between the piston and cylinder and therefore without special costs can be produced.
  • the control means can be adjusted in such a way that even with relatively small pressure drops in the oil circuit (for example a drop in the target pressure from approx. 1.7 to 1. 5 bar) the inlet opening 25 of the pressure medium line 24 is released.
  • the response time of the suction nozzle valve 4 is so short that it is ensured that the suction nozzle valve is closed even before the vacuum pump finally runs out.
  • the control of the suction nozzle valve by the oil pressure in an oil circuit has that of an oil arranged on the pump shaft pump is supplied, the advantage of a fast and safe mode of operation, since the operating state of the pump can clearly be derived from the oil pressure in the oil circuit.
  • the outlet opening 14 of the line 13 is assigned a resilient cover 41 which - together with a special design of the wall 42 in the region of the outlet opening 14 - fulfills several functions.
  • the outlet opening 14 is surrounded by a concentric groove 43 in the wall 42 which extends into a bore 44 through which the oil serving to supply the pump chamber passes.
  • This bore is also equipped with a throttle 45, the size of which is adapted to the suction power of the respective pump.
  • the resilient cover 41 which preferably consists of an elastic steel band section, covers both the outlet opening 14 of the oil pressure line 13 and the bore 44.
  • the pressure oil is expanded to the pressure in the oil box as a result of the throttle 15 and initially flows into the groove 43 surrounding the outlet opening 14. Part of the oil flows out of this groove, which is connected to the bore 44, as a result of the Suction effect of the pump chamber through the bore 44 or throttle 45. Excess oil is returned to oil reservoir 2.
  • the resilient cover 41 ensures that only such oil flows through the bore 44 and the throttle 45 that has emerged from the outlet opening 14. Therefore, only oil that has flowed through the oil filter 19 enters the pump chamber.
  • the pump room is therefore no longer affected by dirty oil. Nevertheless, the pump works like a self-priming pump, i.e. it determines the amount of oil it needs itself. In high pressure ranges e.g. Small amounts of oil through the throttle 45 so that undesirably high oil vapor components are not present in the pumped media emerging from the pump. Regardless of this, it is ensured that the bearings are supplied with pressure oil.
  • the resilient cover and the special groove design ensure that the oil is shut off when the pump is not running.
  • the negative pressure acting through the bore 44 in the pump chamber causes the resilient cover to bear tightly against the wall 42.
  • the cover completely blocks the bore 44, so that the oil supply to the vacuum pump is stopped.
  • Fig. 2 shows a rotary vane vacuum pump.
  • the conveyed gases pass through the suction nozzle 3, the open suction nozzle valve 4, via the suction channel 51, which is not visible in the drawing plane and is therefore shown as an arrow, into the pump chamber 52, in which the rotor 53 with the slides 54 is located.
  • the compressed gases pass through the outlet channel 55 into the oil box 1, which is filled with oil up to the line 56, so that the resilient cover 41 lies below the oil level.
  • the actual exhaust pipe is not shown.
  • the end wall 42 of the pump body 57 arranged in the oil box 1 is shown in view in its lower part. 3 and 4 show sections through this end wall at the level of lines 111-111 and IV-IV.
  • the oil pressure line 13 ends with the throttle point 15.
  • the bearing of the pump shaft (not shown) arranged in the end wall 42 is also lubricated via the branch line 17 designed as a bore. This bore is closed to the outside by the plug 58.
  • the resilient cover 41 (shown in broken lines in FIG. 2) is fastened on the end wall 42 by means of the screws 46, 47. It covers the two openings 14 and 44 and the groove 43 surrounding the opening 14.
  • the nozzle 15 is produced by drilling the end wall 42 on both sides.
  • the nozzle 45 is screwed into the end wall 42 by means of a thread 59, so that different nozzles can be used depending on the suction power of the pump.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Description

Die Erfindung bezieht sich auf eine ölgedichtete Vakuumpumpe mit einem Ölkreislauf zur Versorgung der Lagerungen und des Pumpenraumes mit Öl und einem in Ölkreislauf angeordneten Ventil für die Absperrung der Ölzufuhr zum Pumpenraum bei stillstehender Pumpe.The invention relates to an oil-sealed vacuum pump with an oil circuit for supplying the bearings and the pump chamber with oil and an oil circuit valve for shutting off the oil supply to the pump chamber when the pump is at a standstill.

Aus der G B- PS Nr. 875444 ist eine ölgedichtete Vakuumpumpe dieser Art bekannt. Die Ölpumpe des Ölkreislaufs saugt das Öl aus dem im Pumpengehäuse befindlichen Ölvorrat und fördert es zu einer Art Rückschlagventil, dessen Verschlussstück unter der Wirkung einer sehr schwachen Feder steht, so dass der Öldruck im Ölkreislauf nur wenig über dem Umgebungsdruck liegt. Vom sich gegen den Federdruck öffnenden Ventil gelangt das im Überschuss von der Ölpumpe geförderte Öl über die Lagerung der Pumpenwelle in den Pumpenraum und wird von dort aus über das Auslassventil dem Ölvorrat wieder zugeführt. Nachteilig daran ist, dass den Lagerungen kein Öl mit einem deutlich über dem Umgebungsdruck liegenden Druck zugeführt werden kann, was für eine sichere und kontinuierliche Lagerschmierung wünschenswert ist. Es wäre denkbar, die Stärke der Feder des Rückschlagventils grösser zu wählen, so dass der Öldruck im Ölkreislauf ansteigt. Das würde jedoch bedeuten, dass das der Abdichtung des Drehkolbens dienende Öl ständig mit erhöhtem Druck in den Pumpenraum eingespritzt wird. Daran wäre nachteilig, dass in die bei hohen Ansaugdrücken in grosser Menge geförderten Gase unnötig viel Öl eingespritzt wird, was nicht nur den ÖIverbrauch beim Betrieb der Pumpe mit hohen Ansaugdrücken unnötig steigert, sondern auch eine störende Umweltbelastung infolge der hohen Ölanteile im von der Pumpe ausgestossenen Gas darstellt.An oil-sealed vacuum pump of this type is known from G B-PS No. 875444. The oil pump in the oil circuit sucks the oil from the oil supply in the pump housing and conveys it to a kind of non-return valve, the closing piece of which is under the action of a very weak spring, so that the oil pressure in the oil circuit is only slightly above the ambient pressure. From the valve, which opens against the spring pressure, the excess oil pumped by the oil pump reaches the pump chamber via the bearing of the pump shaft and from there is returned to the oil reservoir via the outlet valve. The disadvantage of this is that no oil can be supplied to the bearings with a pressure that is significantly above the ambient pressure, which is desirable for safe and continuous bearing lubrication. It would be conceivable to choose a larger spring force for the check valve so that the oil pressure in the oil circuit rises. However, this would mean that the oil used to seal the rotary lobe is constantly injected into the pump chamber with increased pressure. This would be disadvantageous in that unnecessarily much oil is injected into the gases pumped in large quantities at high suction pressures, which not only unnecessarily increases the oil consumption when operating the pump with high suction pressures, but also a disturbing environmental impact as a result of the high oil content in the gas emitted by the pump Represents gas.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, eine ölgedichtete Vakuumpumpe der eingangs genannten Art zu schaffen, bei der trotz sicherer Lagerschmierung mit Drucköl ein Pumpenbetrieb bis zu 1000 mbar Ansaugdruck ohne unnötige Belastung der geförderten Gase mit Öldämpfen gewährleistet ist.The present invention has for its object to provide an oil-sealed vacuum pump of the type mentioned, in which, despite safe bearing lubrication with pressure oil, pump operation of up to 1000 mbar suction pressure is ensured without unnecessarily loading the pumped gases with oil vapors.

Erfindungsgemäss wird diese Aufgabe dadurch gelöst, dass der der Versorgung der Lagerungen des Pumpenraumes mit Öl dienende Ölkreislauf eine Druckstufe zum Abbau des von der Ölpumpe erzeugten Überdruckes auf den Umgebungsdruck aufweist und dass die zu den Lagerungen führenden Abzweigungen - bezogen auf die Richtung des strömenden Öls - vor der Druckstufe und die zum Pumpenraum führende Abzweigleitung sowie das Absperrventil hinter der Druckstufe angeordnet sind. Bei einer in dieser Weise ausgebildeten Vakuumpumpe kann mit Hilfe der Ölpumpe und der Druckstufe ein relativ hoher Druck im ersten Teil des Ölkreislaufs aufrechterhalten werden, von dem aus die Versorgung der Lagerungen mit Schmieröl erfolgt. Die Versorgung des Pumpenraumes erfolgt mit druckentlastetem Öl, so dass die Pumpe als selbstansaugende Pumpe arbeitet. Eine derartige Pumpe saugt bei hohen Ansaugdrücken wenig Öl, bei Enddruckbetrieb viel Öl an. Der erhöhte Ölverbrauch und die störende Umweltbelastung bei hohen Ansaugdrücken sind deshalb stark reduziert. Ferner erlaubt die Ölversorgung der Lagerungen aus einem Ölkreislauf mit relativ hohem Druck, in diesem Teil der Ölleitung ein Ölfilter einzuschalten, über den eine relativ hohe Druckdifferenz abfällt, so dass den Lagerungen nur gereinigtes Öl zugeführt werden kann. Auch die Überwachung der Pumpe über den Öldruck, der eine eindeutige Aussage überden Betriebszustand der Pumpe zulässt, ist möglich. Schliesslich hatdie Versorgung des Pumpenraumes mit Öl aus dem sich anschliessenden druckentlasteten Teil des Ölkreislaufs den Vorteil, dass auch in den Pumpenraum ausschliesslich gereinigtes Öl gelangt. Durch das Absperrventil ist sichergestellt, dass beim Abstellen der Pumpe die Ölmenge, die innerhalb des Pumpenraumes bleibt, zuverlässig begrenzt ist. Dies ergibt entscheidende Vorteile beim Kaltstart der Pumpe, was einen direkten Einfluss auf die Dimensionierung des Motors der Pumpe hat. Ein unerwünschter Ölanstieg in der Pumpe und im Saugstutzen bei versehentlichem Rückwärtslauf der Pumpe ist ebenfalls zuverlässig verhindert.According to the invention, this object is achieved in that the oil circuit serving to supply the bearings of the pump chamber with oil has a pressure stage for reducing the overpressure generated by the oil pump to the ambient pressure and that the branches leading to the bearings - based on the direction of the flowing oil - upstream of the pressure stage and the branch line leading to the pump chamber as well as the shut-off valve behind the pressure stage. In a vacuum pump designed in this way, the oil pump and the pressure stage can be used to maintain a relatively high pressure in the first part of the oil circuit, from which the bearings are supplied with lubricating oil. The pump room is supplied with pressure-relieved oil, so that the pump works as a self-priming pump. Such a pump sucks little oil at high suction pressures, and a lot of oil at end pressure operation. The increased oil consumption and the disturbing environmental impact at high intake pressures are therefore greatly reduced. Furthermore, the oil supply to the bearings from an oil circuit with a relatively high pressure enables an oil filter to be switched on in this part of the oil line, via which a relatively high pressure difference drops, so that only cleaned oil can be supplied to the bearings. It is also possible to monitor the pump via the oil pressure, which allows a clear statement about the operating state of the pump. Finally, the supply of oil to the pump chamber from the subsequent pressure-relieved part of the oil circuit has the advantage that only cleaned oil gets into the pump chamber. The shut-off valve ensures that when the pump is switched off, the amount of oil that remains within the pump chamber is reliably limited. This gives decisive advantages when the pump is cold started, which has a direct influence on the dimensioning of the motor of the pump. An undesirable increase in oil in the pump and in the suction port when the pump is accidentally reversed is also reliably prevented.

Weitere Vorteile und Einzelheiten der Erfindung sollen anhand von in den Fig. 1 bis 4 dargestellten Ausführungsbeispielen erläutert werden. Es zeigen:

  • Fig. 1 ein Schema eines Ölkreislaufs in einer Vakuumpumpe nach der Erfindung mit hydropneumatisch gesteuertem Saugstutzenventil,
  • Fig. 2 ein Ausführungsbeispiel für eine Vakuumpumpe nach der Erfindung, teilweise im Schnitt, teilweise in Ansicht der vorderen Stirnwand des Pumpenkörpers,
  • Fig. 3 einen Schnitt durch die Stirnwand des Pumpenkörpers nach der Linie 111-111 in Fig. 2, und
  • Fig. 4 einen Schnitt durch die Stirnwand des Pumpenkörpers nach der Linie IV-IV in Fig. 2.
Further advantages and details of the invention will be explained with reference to exemplary embodiments shown in FIGS. 1 to 4. Show it:
  • 1 is a diagram of an oil circuit in a vacuum pump according to the invention with a hydropneumatically controlled suction port valve,
  • 2 shows an embodiment of a vacuum pump according to the invention, partly in section, partly in view of the front end wall of the pump body,
  • Fig. 3 shows a section through the end wall of the pump body along the line 111-111 in Fig. 2, and
  • 4 shows a section through the end wall of the pump body along the line IV-IV in FIG. 2.

Beim Schema nach Fig. 1 sind im wesentlichen nur diejenigen Teile der erfindungsgemässen Vakuumpumpe dargestellt, die im Rahmen der Erfindung eine besondere Rolle spielen. Mit 1 ist der Ölkasten oder das äussere Pumpengehäuse bezeichnet, das teilweise mit Öl 2 gefüllt ist. Im Schnitt dargestellt ist weiterhin der Saugstutzen 3 mit dem Saugstutzenventil 4, das von dem plattenförmigen Ventilsitz 5 mit der Öffnung 6 und dem Ventilteller 7 gebildet wird. Der Ventilteller 7 steht mit einem Kolben 8 in Verbindung, der im Zylinder 9 verschiebbar angeordnet ist.1 only those parts of the vacuum pump according to the invention are shown which play a special role in the context of the invention. With 1 the oil box or the outer pump housing is designated, which is partially filled with oil 2. Also shown in section is the suction nozzle 3 with the suction nozzle valve 4, which is formed by the plate-shaped valve seat 5 with the opening 6 and the valve plate 7. The valve plate 7 is connected to a piston 8, which is arranged displaceably in the cylinder 9.

Der Ölkreislauf der Pumpe wird gebildet von der Ansaugleitung 11, über die mittels der Ölpumpe 12 Öl aus dem Ölvorrat 2 in die Öldruckleitung 13 gefördert wird. Im Bereich der Austrittsöffnung 14 der Öldruckleitung 13 ist eine Drossel 15 angeordnet, welche für die Aufrechterhaltung des gewünschten Öldruckes (zwischen 1,5 und 2, vorzugsweise 1,7 bar) sorgt und über die der Abbau des Druckes auf den Druck im Ölkasten 1 erfolgt. Über Abzweigungen 16,17,18 erfolgt die Versorgung der in der Pumpe vorhandenen Lagerungen mit Drucköl. Drei Ölversorgungsleitungen 16, 17, 18 sind im Falle einer zweistufigen Pumpe erforderlich, bei der zwei Endlager und ein Zwischenlager der beiden Rotoren mit Öl versorgt werden müssen. Im Falle einer einstufigen Pumpe reichen zwei der drei Abzweigleitungen aus. Nach dem Durchströmen der Lagerungen gelangt das in die Abzweigleitungen 16,17,18 eingetretene Öl wieder in den Ölvorrat 2.The oil circuit of the pump is formed by the suction line 11, via which oil is conveyed from the oil reservoir 2 into the oil pressure line 13 by means of the oil pump 12. In the area of the outlet opening 14 of the oil pressure line 13, a throttle 15 is arranged, which ensures the maintenance of the desired oil pressure (between 1.5 and 2, preferably 1.7 bar) and via which the pressure is reduced to the pressure in the oil box 1 . The bearings in the pump are supplied with pressure oil via branches 16, 17, 18. Three oil supply lines 16, 17, 18 are required in the case of a two-stage pump This means that two repositories and one intermediate bearing of the two rotors have to be supplied with oil. In the case of a single-stage pump, two of the three branch lines are sufficient. After flowing through the bearings, the oil that has entered the branch lines 16, 17, 18 returns to the oil reservoir 2.

In die Druckölleitung 13 ist unmittelbar hinter der Ölpumpe 12 ein Ölfilter 19 eingeschaltet, so dass sichergestellt ist, dass ausschliesslich gereinigtes Öl durch die Leitung 13 und durch die daran angeschlossenen Abzweigleitungen strömt.An oil filter 19 is switched into the pressure oil line 13 immediately behind the oil pump 12, so that it is ensured that only cleaned oil flows through the line 13 and through the branch lines connected to it.

Eine weitere Abzweigleitung 21 mündet in den Steuerzylinder 22, in dem sich der Steuerkolben 23 befindet. Auf der der Einmündung der Leitung 21 gegenüberliegenden Seite des Kolbens 23 mündet die Druckmittelleitung 24 in den Zylinder 22, deren anderes Ende mit dem Zylinder 9 auf der dem Ventilteller 7 abgewandten Seite des Kolbens 8 verbunden ist. Die Eintrittsöffnung 25 der Druckmittelleitung 24 in den Zylinder 22 ist als Ventilsitz ausgebildet. Dazu ist in die Eintrittsöffnung 25 ein Stöpsel 26 mit einem Dichtwulst 27 eingesteckt. Als Verschlussglied dient die Stirnseite 28 eines zylindrischen Ansatzes 29 am Steuerkolben 23 mit gegenüber dem Steuerkolben verringertem Durchmesser. Der Steuerkolben 23 steht unter der Wirkung einer Feder 31, die zwischen dem Steuerkolben 23 und der Stirnwand 32 mit der Eintrittsöffnung 25 der Druckmittelleitung 24 angeordnet und als Druckfeder ausgebildet ist. Der zylindrische Ansatz 29 ist mittels des Gewindes 33 in den Steuerkolben 23 einschraubbar, so dass auf die im Schliesszustand des Steuerventils 27, 28 wirkende Kraft der Feder 31 Einfluss genommen werden kann.Another branch line 21 opens into the control cylinder 22, in which the control piston 23 is located. On the side of the piston 23 opposite the mouth of the line 21, the pressure medium line 24 opens into the cylinder 22, the other end of which is connected to the cylinder 9 on the side of the piston 8 facing away from the valve plate 7. The inlet opening 25 of the pressure medium line 24 in the cylinder 22 is designed as a valve seat. For this purpose, a plug 26 with a sealing bead 27 is inserted into the inlet opening 25. The end face 28 of a cylindrical projection 29 on the control piston 23 with a reduced diameter compared to the control piston serves as the closure member. The control piston 23 is under the action of a spring 31, which is arranged between the control piston 23 and the end wall 32 with the inlet opening 25 of the pressure medium line 24 and is designed as a compression spring. The cylindrical extension 29 can be screwed into the control piston 23 by means of the thread 33, so that the force of the spring 31 acting in the closed state of the control valve 27, 28 can be influenced.

In den Zylinder 22 mündet eine weitere Leitung 34, die mit einem oben offenen Ölvorratsgefäss 35 geringen Volumens verbunden ist. Die Einmündung der Leitung 34 in den Zylinder 22 liegt auf der der Einmündung der Leitung 21 entgegengesetzten Seite des Steuerkolbens 23.A further line 34 opens into the cylinder 22 and is connected to an oil reservoir 35 of small volume which is open at the top. The junction of the line 34 in the cylinder 22 lies on the side of the control piston 23 opposite the junction of the line 21.

Während des Betriebs einer nach diesem Schema aufgebauten Pumpe fördert die Ölpumpe 12 Öl aus dem Ölvorrat 2 in die Öldruckleitung 13. Die Ölpumpe 12 kann als Drehschieberpumpe oder Zahnradpumpe ausgebildet sein und ist in bekannter Weise mit der Pumpenwelle als Antrieb gekoppelt (vgl. GB-PS Nr. 875444). Die Fördereigenschaften der Pumpe 12 und die Grösse der Drossel 15 sind so bemessen, dass sich nach dem Anlaufen der Vakuumpumpe der gewünschte Öldruck in der Leitung 13 aufbaut und gehalten wird. Dieser Druck wirkt auf den Kolben 23 und überwindet die Kraft der Feder 31, so dass die Eintrittsöffnung 25 der Druckmittelleitung 24 verschlossen ist. Das Saugstutzenventil 4 befindet sich in seiner Offenstellung, so dass der an den Saugstutzen 3 angeschlossene Rezipient evakuiert wird.During the operation of a pump constructed according to this scheme, the oil pump 12 conveys oil from the oil supply 2 into the oil pressure line 13. The oil pump 12 can be designed as a rotary vane pump or gear pump and is coupled in a known manner to the pump shaft as a drive (cf. GB-PS No. 875444). The delivery properties of the pump 12 and the size of the throttle 15 are dimensioned such that the desired oil pressure is built up and maintained in the line 13 after the vacuum pump has started. This pressure acts on the piston 23 and overcomes the force of the spring 31, so that the inlet opening 25 of the pressure medium line 24 is closed. The suction nozzle valve 4 is in its open position, so that the recipient connected to the suction nozzle 3 is evacuated.

Während dieses Betriebszustandes strömen durch die Öldruckleitung 13 bestimmte Ölmengen, die mit 01, O2 und 03 bezeichnet sind. Der Kolben 23 bildet mit der Wand des Zylinders 22 einen relativ grossen Spalt 36, so dass sich der Zylinderraum 22 unterhalb des Kolbens 23 und der Ölvorratsraum 35 mit Öl füllen. Wegen des Spaltes 36 wird ein ständiger Ölstrom mit der Menge Q4 aufrechterhalten. Überschüssiges Öl gelangt vom Ölvorrat 35 wieder in den Ölvorrat 2. Die Ölpumpe 12 ist so dimensioniert, dass der gesamte Ölkreislauf mit Überschussöl gefahren wird, d.h. zu jeder Zeit strömt mehr Öl durch den Olkreislauf, als von der Pumpe benötigt wird.During this operating state, certain oil quantities, which are denoted by 0 1 , O 2 and 0 3 , flow through the oil pressure line 13. The piston 23 forms a relatively large gap 36 with the wall of the cylinder 22, so that the cylinder space 22 below the piston 23 and the oil reservoir 35 fill with oil. Because of the gap 36, a constant oil flow with the amount Q 4 is maintained. Excess oil flows from the oil supply 35 back into the oil supply 2. The oil pump 12 is dimensioned such that the entire oil circuit is run with excess oil, ie at any time more oil flows through the oil circuit than is required by the pump.

Wird die Pumpe abgestellt, nimmt gleichzeitig die von der Ölpumpe 12 geförderte Ölmenge ab, so dass der Öldruck in der Leitung 13 nachlässt. Bei Unterschreiten eines bestimmten Druckes wird die Eintrittsöffnung 25 freigegeben, so dass infolge des auf der Oberfläche des Öls in dem ÖIvorrat 35 herrschenden Atmosphärendruckes Öi in die Druckmittelleitung 24 gedrückt wird und unter den Kolben 8 in den Zylinder 9 gelangt. Die unterhalb des Kolbens 23 und im Ölvorrat 35 befindliche Ölmenge ist so gering, dass das in den Zylinder 9 gelangende Öl im wesentlichen nur der Abdichtung des Kolbens 8 gegenüber seiner Zylinderwand dient. Das eigentliche Druckmittel zur Betätigung des Kolbens 8 ist die Luft, die im Anschluss an das Öl durch den Ölvorrat 35 in die Druckmittelleitung 24 gelangt. Die gesamte, im Zylinder 22 und im Ölvorratsgefäss 35 befindliche Ölmenge beträgt einige Kubikzentimeter. Sie soll so gering sein, dass sie im wesentlichen nur der Abdichtung des zwischen dem Kolben 8 und dem Zylinder 9 bestehenden Spaltes dient. Diese Vorgänge bewirken ein Schliessen des Saugstutzenventils 4 ohne den unerwünschten Luftschluck. Nachdem das Saugstutzenventil 4 geschlossen ist und die nachdrängende Luft das zwischen dem Kolben 8 und der Zylinderwandung 9 befindliche Öl verdrängt hat, erfolgt hierüber die Belüftung des Pumpenraums. Die Funktion der Saugstutzenventilsteuerung ist unabhängig von der Existenz eines Ölfilters 19, d.h. auch bei einem Ölkreislauf ohne Ölfilter 19 (vgl. gestrichelt eingezeichneten Leitungsabschnitt 20) arbeiten das Saugstutzenventil und seine Steuermittel einwandfrei.If the pump is switched off, the amount of oil delivered by the oil pump 12 decreases at the same time, so that the oil pressure in the line 13 decreases. When the pressure falls below a certain value, the inlet opening 25 is opened so that owing to the atmospheric pressure prevailing on the surface of the oil in the oil reservoir 35, oil is pressed into the pressure medium line 24 and reaches the cylinder 9 under the piston 8. The amount of oil located below the piston 23 and in the oil reservoir 35 is so small that the oil entering the cylinder 9 essentially serves only to seal the piston 8 against its cylinder wall. The actual pressure medium for actuating the piston 8 is the air which, following the oil, passes through the oil supply 35 into the pressure medium line 24. The total amount of oil in the cylinder 22 and in the oil reservoir 35 is a few cubic centimeters. It should be so small that it essentially serves only to seal the gap existing between the piston 8 and the cylinder 9. These processes cause the suction nozzle valve 4 to close without the undesirable air intake. After the suction port valve 4 is closed and the urging air has displaced the oil between the piston 8 and the cylinder wall 9, the pump chamber is ventilated. The function of the intake valve control is independent of the existence of an oil filter 19, i.e. Even in an oil circuit without an oil filter 19 (see line section 20 shown in broken lines), the suction nozzle valve and its control means work perfectly.

Ein besonderer Vorteil der beschriebenen Ausführung des Saugstutzenventils 4 und seiner in Abhängigkeit vom Öldruck arbeitenden Steuermittel liegt noch darin, dass beider Zylinder/ Kolben- Einrichtungen 8, 9 bzw. 22, 23 wegen der erwünschten Spalte zwischen Kolben und Zylinder kaum toleranzanfällig sind und deshalb ohne besonderen Kostenaufwand herstellbar sind. Durch geeignete Wahl der strömenden Ölmengen Q, und Q4 und durch entsprechendes Anpassen der Kraft der Feder 31 können die Steuermittel derart justiert werden, dass bereits bei relativ kleinen Drucksenkungen im Ölkreislauf (z.B. ein Absinken des Solldruckes von ca. 1,7 auf 1,5 bar) die Eintrittsöffnung 25 der Druckmittelleitung 24 freigegeben wird. Die Ansprechzeit des Saugstutzenventils 4 ist aufgrund der hydropneumatischen Betätigung so klein, dass sichergestellt ist, dass bereits vor dem endgültigen Auslaufen der Vakuumpumpe das Saugstutzenventil geschlossen ist. Generell hat die Ansteuerung des Saugstutzenventils durch den Öldruck in einem Ölkreislauf, der von einer auf der Pumpenwelle angeordneten ÖIpumpe versorgt wird, den Vorteil einer schnellen und sicheren Betriebsweise, da vom Öldruck im Ölkreislauf eindeutig der Betriebszustand der Pumpe abgeleitet werden kann.A particular advantage of the described embodiment of the suction nozzle valve 4 and its control means that work as a function of the oil pressure is that both cylinder / piston devices 8, 9 and 22, 23 are hardly susceptible to tolerances because of the desired gap between the piston and cylinder and therefore without special costs can be produced. By a suitable choice of the flowing oil quantities Q, and Q 4 and by correspondingly adjusting the force of the spring 31, the control means can be adjusted in such a way that even with relatively small pressure drops in the oil circuit (for example a drop in the target pressure from approx. 1.7 to 1. 5 bar) the inlet opening 25 of the pressure medium line 24 is released. Due to the hydropneumatic actuation, the response time of the suction nozzle valve 4 is so short that it is ensured that the suction nozzle valve is closed even before the vacuum pump finally runs out. In general, the control of the suction nozzle valve by the oil pressure in an oil circuit has that of an oil arranged on the pump shaft pump is supplied, the advantage of a fast and safe mode of operation, since the operating state of the pump can clearly be derived from the oil pressure in the oil circuit.

Der Austrittsöffnung 14 der Leitung 13 ist eine federnde Abdeckung 41 zugeordnet, die - gemeinsam mit einer besonderen Gestaltung der Wandung 42 im Bereich der Austrittsöffnung 14- mehrere Funktionen erfüllt. Die Austrittsöffnung 14 ist von einer konzentrischen Nut 43 in der Wandung 42 umgeben, die bis in eine Bohrung 44 reicht, durch die das der Versorgung des Pumpenraumes dienende Öl hindurchtritt. Diese Bohrung ist ebenfalls mit einer Drossel 45 ausgerüstet, deren Grösse der Saugleistung der jeweiligen Pumpe angepasst ist. Die federnde Abdeckung 41, die vorzugsweise aus einem elastischen Stahlbandabschnitt besteht, überdeckt sowohl die Austrittsöffnung 14 der Öldruckleitung 13 als auch die Bohrung 44. Ihre Kraft und der Abstand der Befestigungspunkte 46, 47 von den Ölkanälen 13, 44 sind so gewählt, dass sie für das aus der Austrittsöffnung 14 austretende Öl eine Druckstufe einer vernachlässigbaren Druckdifferenz darstellen. Praktisch tritt das Öl mit dem Druck des Ölkastens aus der Austrittsöffnung 14 aus. Ausserdem gilt auch an dieser Stelle des Ölkreislaufs, dass er mit Überschussöl gefahren wird, d.h. dass selbst bei Enddruckbetrieb der Pumpe durch die Austrittsöffnung 14 mehr Öl austritt, als von der Pumpe durch die Bohrung 44 bzw. Drossel 45 angesaugt wird.The outlet opening 14 of the line 13 is assigned a resilient cover 41 which - together with a special design of the wall 42 in the region of the outlet opening 14 - fulfills several functions. The outlet opening 14 is surrounded by a concentric groove 43 in the wall 42 which extends into a bore 44 through which the oil serving to supply the pump chamber passes. This bore is also equipped with a throttle 45, the size of which is adapted to the suction power of the respective pump. The resilient cover 41, which preferably consists of an elastic steel band section, covers both the outlet opening 14 of the oil pressure line 13 and the bore 44. Their force and the distance of the fastening points 46, 47 from the oil channels 13, 44 are selected such that they are suitable for the oil emerging from the outlet opening 14 represents a pressure level of a negligible pressure difference. In practice, the oil emerges from the outlet opening 14 with the pressure of the oil box. In addition, it also applies at this point in the oil circuit that it is operated with excess oil, i.e. that even during final pressure operation of the pump, more oil emerges through the outlet opening 14 than is sucked in by the pump through the bore 44 or throttle 45.

Während des Betriebs der Pumpe wird das Drucköl infolge der Drossel 15 auf den Druck im Ölkasten entspannt und strömt zunächst in die die Austrittsöffnung 14 umgebende Nut 43. Aus dieser Nut, die mit der Bohrung 44 in Verbindung steht, strömt ein Teil des Öles infolge der Saugwirkung des Pumpenraumes durch die Bohrung 44 bzw. Drossel 45 hindurch. Überschüssiges Öl gelangt in den Ölvorrat 2 zurück. Durch die federnde Abdeckung 41 ist sichergestellt, dass durch die Bohrung 44 und die Drossel 45 nur solches Öl strömt, das aus der Austrittsöffnung 14 ausgetreten ist. In den Pumpenraum gelangt deshalb ausschliesslich Öl, das den Ölfilter 19 durchströmt hat. Beeinträchtigungen des Pumpenraumes durch verschmutztes Öl treten deshalb nicht mehr auf. Dennoch arbeitet die Pumpe wie eine selbstansaugende Pumpe, d.h. sie bestimmt die von ihr benötigte Ölmenge selbst. In hohen Druckbereichen treten z.B. geringe Ölmengen durch die Drossel 45 hindurch, so dass unerwünscht hohe Öldampfanteile in den aus der Pumpe austretenden geförderten Medien nicht vorhanden sind. Unabhängig davon ist sichergestellt, dass die Lagerungen mit Drucköl versorgt werden.During operation of the pump, the pressure oil is expanded to the pressure in the oil box as a result of the throttle 15 and initially flows into the groove 43 surrounding the outlet opening 14. Part of the oil flows out of this groove, which is connected to the bore 44, as a result of the Suction effect of the pump chamber through the bore 44 or throttle 45. Excess oil is returned to oil reservoir 2. The resilient cover 41 ensures that only such oil flows through the bore 44 and the throttle 45 that has emerged from the outlet opening 14. Therefore, only oil that has flowed through the oil filter 19 enters the pump chamber. The pump room is therefore no longer affected by dirty oil. Nevertheless, the pump works like a self-priming pump, i.e. it determines the amount of oil it needs itself. In high pressure ranges e.g. Small amounts of oil through the throttle 45 so that undesirably high oil vapor components are not present in the pumped media emerging from the pump. Regardless of this, it is ensured that the bearings are supplied with pressure oil.

Weiterhin wird durch die federnde Abdeckung und die spezielle Nutausbildung eine Ölabsperrung bei Stillstand der Pumpe erreicht. In diesem Betriebszustand bewirkt der durch die Bohrung 44 hindurch wirkende Unterdruck im Pumpenraum, dass sich die federnde Abdeckung dicht an die Wandung 42 anlegt. Dadurch versperrt die Abdekkung die Bohrung 44 vollständig, so dass die Ölzufuhr zur Vakuumpumpe unterbleibt. Durch diese Lösung ergibt sich ein weiterer Vorteil. Es existiert generell das Problem, dass es bei einem versehentlichen Rückwärtslauf der Pumpe (infolge falschen Stromanschlusses) zu einem unerwünschten Ölanstieg im Saugstutzen kommt. Durch diese Anordnung wird dieser Ölanstieg zuverlässig verhindert.Furthermore, the resilient cover and the special groove design ensure that the oil is shut off when the pump is not running. In this operating state, the negative pressure acting through the bore 44 in the pump chamber causes the resilient cover to bear tightly against the wall 42. As a result, the cover completely blocks the bore 44, so that the oil supply to the vacuum pump is stopped. This solution has another advantage. There is generally the problem that if the pump runs backwards accidentally (as a result of incorrect power connection), there is an undesirable increase in oil in the suction nozzle. This arrangement reliably prevents this increase in oil.

Fig. 2 zeigt eine Drehschiebervakuumpumpe. Während des Betriebs der Pumpe gelangen die geförderten Gase durch den Saugstutzen 3, das offene Saugstutzenventil 4, über den in der Zeichnungsebene nicht sichtbaren und deshalb als Pfeil dargestellten Saugkanal 51 in den Pumpenraum 52, in dem sich der Rotor 53 mit den Schiebern 54 befindet. Die komprimierten Gase gelangen durch den Austrittskanal 55 in den Ölkasten 1, der bis zur Linie 56 mit Öl gefüllt ist, so dass die federnde Abdeckung 41 unterhalb des Ölspiegels liegt. Der eigentliche Auspuffstutzen ist nicht dargestellt.Fig. 2 shows a rotary vane vacuum pump. During operation of the pump, the conveyed gases pass through the suction nozzle 3, the open suction nozzle valve 4, via the suction channel 51, which is not visible in the drawing plane and is therefore shown as an arrow, into the pump chamber 52, in which the rotor 53 with the slides 54 is located. The compressed gases pass through the outlet channel 55 into the oil box 1, which is filled with oil up to the line 56, so that the resilient cover 41 lies below the oil level. The actual exhaust pipe is not shown.

Die Stirnwand 42 des im Ölkasten 1 angeordneten Pumpenkörpers 57 ist in ihrem unteren Teil in Ansicht dargestellt. Schnitte durch diese Stirnwand in Höhe der Linien 111-111 und IV-IV zeigen die Fig. 3 und 4. In der Stirnwand 42 endet die Öldruckleitung 13 mit der Drosselstelle 15. Vor der Entspannung des Öls auf den Druck im Ölkasten infolge der Drossel 15 erfolgt noch die Schmierung des in der Stirnwand 42 angeordneten Lagers der Pumpenwelle (nicht dargestellt) über die als Bohrung ausgebildete Abzweigleitung 17. Nach aussen hin ist diese Bohrung durch den Stöpsel 58 verschlossen.The end wall 42 of the pump body 57 arranged in the oil box 1 is shown in view in its lower part. 3 and 4 show sections through this end wall at the level of lines 111-111 and IV-IV. In the end wall 42, the oil pressure line 13 ends with the throttle point 15. Before the oil is released to the pressure in the oil box as a result of the throttle 15 the bearing of the pump shaft (not shown) arranged in the end wall 42 is also lubricated via the branch line 17 designed as a bore. This bore is closed to the outside by the plug 58.

Mittels der Schrauben 46, 47 ist die federnde Abdeckung 41 (in Fig. 2 gestrichelt dargestellt) auf der Stirnwand 42 befestigt. Sie überdeckt die beiden Öffnungen 14 und 44 sowie die die Öffnung 14 umgebende Nut43. Die Düse 15 ist durch beidseitiges Bohren der Stirnwand 42 hergestellt. Die Düse 45 ist mittels eines Gewindes 59 in die Stirnwand 42 eingeschraubt, so dass je nach Saugleistung der Pumpe unterschiedliche Düsen verwendet werden können.The resilient cover 41 (shown in broken lines in FIG. 2) is fastened on the end wall 42 by means of the screws 46, 47. It covers the two openings 14 and 44 and the groove 43 surrounding the opening 14. The nozzle 15 is produced by drilling the end wall 42 on both sides. The nozzle 45 is screwed into the end wall 42 by means of a thread 59, so that different nozzles can be used depending on the suction power of the pump.

Claims (9)

1. A oil-tight vacuum pump with an oil-circulating line for supplying the bearings and the pump chamber with oil, and with a valve arranged in the oil-circulating line for cutting off the supply of oil to the pump chamber when the pump is at a standstill, characterized in that the oil-circulating line comprises a pressure stage (15) for reducing the excess pressure produced by the pump (12), to the pressure of the surroundings, and in that the branches (16, 17, 18) leading to the bearings are arranged, in relation to the direction in which the oil flows, upstream of the pressure stage, and the branch line (44) leading to the pump chamber, as well as the cut-off valve (14, 41), are arranged downstream of the pressure stage.
2. A vacuum pump according to Claim 1, characterized in that a throttle or nozzle (15) serves as the pressure stage.
3. A vacuum pump according to Claim 1 or 2, characterized in that the pressure stage is located in an end wall (22) of the pump body (57) provided in the outer pump casing (1).
4. A vacuum pump according to Claim 3, characterized in that the exterior face of the end wall (42) has an outlet opening (14) for the depressurized oil, in that an inlet opening for the line (44) leading to the pump chamber is arranged alongside the outlet opening, and in that the surface of the end wall is so shaped that only excess oil emerging from the outlet opening (14) passes into the line (44).
5. A vacuum pump according to Claim 4, characterized in that the outlet opening (14) is surrounded by a preferably concentrically disposed channel (43), which extends into the line (44) leading to the pump chamber, and in that a resilient cover extends over the two openings (14, 44) and the channel (43).
6. A vacuum pump according to Claim 5, characterized in that the resilient cover consists of a resilient length of steel strip.
7. A vacuum pump according to one of Claims 4, 5 or 6, characterized in that a further throttle or nozzle (45) is provided in that portion of the line (44) leading into the pump chamber that lies within the wall (42).
8. A vacuum pump according to Claim 7, characterized in that the nozzle (45) is secured by means of a screw-thread (59) formed in the end wall (42).
9. A vacuum pump according to one of Claims 4 to 8, characterized in that a line (17), formed by a bore and leading to the pump-shaft bearing in the end wall (42), is provided in this end wall in such manner that it crosses the pressure line (13), forming the oil-circulating line, upstream of the pressure stage (15), and in that this bore is closed off at the exterior.
EP82109588A 1981-12-17 1982-10-16 Oil-sealed vacuum pump Expired EP0084084B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3150000 1981-12-17
DE19813150000 DE3150000A1 (en) 1981-12-17 1981-12-17 OIL-SEALED VACUUM PUMP

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EP0084084A1 EP0084084A1 (en) 1983-07-27
EP0084084B1 true EP0084084B1 (en) 1985-02-06

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DE3262232D1 (en) 1985-03-21
EP0084084A1 (en) 1983-07-27
US4525129A (en) 1985-06-25

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