EP2431568A2 - Mounting means for a vacuum pump - Google Patents

Abstract

The vacuum pump (1) has a mounting medium which defines a vertical line corresponding to the direction of gravitational force. An outlet plane contains an outlet and is arranged in relation to the direction of gravitational force below a shaft. The outlet plane is designed parallel to a mounting plane. An intersection point plane includes a point achieved during operation of a centrifuge structure, and is designed parallel to the mounting plane.

Description

The invention relates to a vacuum pump according to the preamble of the first claim.

It is known to rotatably support shafts of vacuum pumps with a lubricant-lubricated roller bearing and, in the case of a plurality of shafts, to synchronize them by a gear with synchronous toothed wheels, so that pistons connected to the shafts roll off each other with a narrow gap. For adequate supply of lubricant is known to provide a lubricant reservoir, in which immersed on one of the shafts slinger dips and lubricates lubricant and distributed in the space in which rolling bearings and / or synchronizing gears are arranged.

It is now observed that the amount of lubricant in the lubricant reservoir decreases over time, the amount of leakage must therefore leak as leakage to other locations of the vacuum pump, in particular in the pumping chamber.

The demands on vacuum pumps in industrial processes have changed and require the reduction of the entry of lubricant into the pump chamber.

It is therefore an object of the invention to provide a vacuum pump with a centrifugal disc, in which the entry of lubricant is reduced in the suction chamber.

This object is achieved by a vacuum pump having the features of the first claim. The dependent therefrom claims 2 to 11 indicate advantageous developments.

The vacuum pump according to the invention is based on the observation that part of the lubricant leakage is caused by lubricant foam. This lubricant foam is generated when the pressure in the room drops and gas escaping from the decreased solubility for gases in liquids in the lubricant. This foam then rises into the area of the shaft and from there into the pump chamber. The arrangement of the drain such that the distance to the edge of the centrifugal disc, which is substantially close to the lubricant level is large, prevents foam passes through this flow to the shaft. As a result, the lubricant leakage is significantly reduced, especially when using the vacuum pump in systems in which the operating pressure in the pump chamber often changes between atmosphere and vacuum, for example so-called load-lock applications. Big means that the distance is chosen so that the spout is either above the rising foam or sufficiently deep in the lubricant fill. The latter prevents lubricant from being sucked through the spout into the area of the shaft. Preferably, the distance is at least half, advantageously two-thirds, the distance between the shaft axis and intersection plane or the distance between the intersection plane and a lowermost point of a space bounding the housing.

The measures presented in the dependent claims lead to a further reduction of the lubricant leakage.

With reference to embodiments and their developments, the invention will be explained in more detail and the representation of its benefits to be deepened.

Fig. 1:

Schematischer Teilschnitt entlang der Welle durch eine Vakuumpumpe,

Fig. 2:

Schematische Darstellung des Raumes quer zur Welle gemäß erstem Ausführungsbeispiel,

Fig. 3:

Teilschnitt längs der Welle mit Ablaufkammer und Fangkammer,

Fig. 4:

Schematische Darstellung von Fangkammer und Rücklauf quer zur Welle gemäß Weiterbildung,

Fig. 5:

Schematische Darstellung mit zwei Wellen, zwei Rückläufen und gemeinsamem Auslauf in einer ersten Ausführung,

Fig. 6:

Schematische Darstellung mit zwei Wellen, zwei Rückläufen und gemeinsamem Auslauf in einer zweiten Ausführung.

Show it:

Fig. 1:

Schematic partial section along the shaft by a vacuum pump,

Fig. 2:

Schematic representation of the space transverse to the shaft according to the first embodiment,

3:

Partial section along the shaft with discharge chamber and catching chamber,

4:

Schematic representation of catch chamber and return across the shaft according to the development,

Fig. 5:

Schematic representation with two shafts, two returns and common outlet in a first embodiment,

Fig. 6:

Schematic diagram with two shafts, two returns and common outlet in a second embodiment.

For the representation of a first example, the Fig. 1 a section through a vacuum pump 1, the housing having a plurality of sections, in particular a gear compartment section 10, a pump chamber section 12 and a distribution space section 14. The housings of the individual sections can be designed separately. Alternatively, a plurality of sections may be arranged together in a housing part. A suction opening 2 provided in the suction chamber section allows the vacuum pump to suck fluid into its suction space. The fluid is ejected through an ejection opening 4, which is likewise provided in the pumping chamber section. The feet 6 are provided as mounting means. Alternatively or additionally, the part of the housing forming the suction or discharge opening, for example by suitable design of the respective flange, may be designed in such a way that the vacuum pump is mounted thereon.

Within the vacuum pump, a shaft 30 is arranged, which is rotatably supported by a roller bearing 32 and a drive-side roller bearing 34. On the pumping space passing through the part of the shaft, a piston 36 is mounted or made integral with her. This causes the pumping effect when the shaft rotates. The rotation of the shaft is effected by a drive 38, for example an asynchronous motor, which may be connected via a magnetic coupling 40 with the shaft. Such an arrangement allows the hermetically sealed separation of the environment and the pump interior, in particular the lubricant-containing housing sections.

At the end of the shaft facing away from the drive, a synchronizing gear 50 is provided in a space provided in the gear compartment section, which interacts with a second synchronizing gear, not visible in this illustration, on a likewise not visible second shaft such that both shafts have the same frequency but opposite directions of rotation move to each other.

Synchronous gear and bearings 32 must be supplied with lubricant. For this purpose, a lubricant filling quantity 72 is present in the space 20, into which a centrifugal structure 60 mounted on the shaft is immersed at least during one phase of the rotary movement. As a result, lubricant is distributed throughout the space 20 and in particular the synchronizing gears and the roller bearing 32 is supplied. From this it passes through a return 54, which opens into a space 20 to the open outlet 58, the lubricant filling 72 back.

Between the drive and drive-side roller bearing, a second space 22 is provided, in which a second centrifugal structure 70 dips into a drive-side lubricant filling 74. As a result, lubricant is distributed in the second space and fed to the rolling bearing 34. From this it passes through a return 64, which opens into an outlet 68, back to the lubricant filling 74.

In a schematic representation shows Fig. 2 the geometric relationships in space 20 in the direction along the shaft axis.

The mounting means 6 define a mounting plane 102 and a perpendicular thereto 100, wherein the vertical corresponds to the direction of gravity.

The shaft axis 112 of the shaft 30 is perpendicular to the plane of the drawing and lies in a wave plane 118 whose surface normal coincides with the vertical 100. The synchronizing gears 50 and 52 are engaged with each other so that the rotational movement of the shaft 30 is transmitted to the second shaft 28. On the shaft 30, the spin structure 60 is arranged. In the example shown, it is designed as a rectangular plate whose corners describe a circular path. With respect to the direction of gravity, this circular path has a lowest point 104, by which an intersection plane 106 is defined, on which the direction of gravity is perpendicular. Alternatively, the spin-on structure can be designed as a solid disk, disk segment or the like. The deepest point is below the lubricant surface 76, so that the spinneret dips into the lubricant filling and takes on re-emergence lubricant from this and distributed in space. In order to reduce loss of drive power, it is advantageous to arrange the intersection plane and lubricant surface close to each other, so that the spin structure dives only so deep that enough lubricant is distributed by it in the room.

When evacuating the vacuum pump, the space 20 is also evacuated. As a result, the pressure is reached at which gas dissolved in the lubricant escapes from this. As a result, the lubricant foams up, the foam rises with an increasing volume in the direction of the vertical.

Through the outlet 58 a plane parallel to the intersection plane outlet level 108 is fixed. The distance 110 between the intersection plane and the outlet plane is chosen to be large, with the outlet plane between the wave plane and the intersection plane lies. Large means that the spout is arranged as far as possible in the foam, preferably outside of the foam. This is limited by the fact that the outlet and the associated return must ensure the return of the lubricant from the area of the shaft. This design ensures that the amount of lubricant reaching the pump chamber along the shaft is considerably reduced.

In an advantageous embodiment, the distance is at least half, better two-thirds, the distance between the intersection plane and the shaft axis of the shaft that carries the spin structure.

In another advantageous embodiment, the angle 122 between a line 120 extending through the outlet and the shaft axis and the outlet plane is at least 10 °. As a result, the above conditions are met.

A further development relates to the volumes that result from the intersection plane and the exit plane. A first volume 114 is bounded by the outlet plane, housing 10 and intersection plane 106. A second volume 116 is located, with respect to the vertical, on the side of the intersection plane facing away from the first volume and is bounded by the intersection plane and housing. Based on the consideration that the second volume substantially contains the necessary for the operation of the vacuum pump and depending on the operating phase foaming amount of lubricant, the first volume 114 is at least twice the second volume 116. Thus, the lubricant can foam without ascending into the outlet , so that the lubricant leakage is reduced again. This effect can be improved if the first volume is three times or four times the second volume.

The mounting means may comprise additional feet 6 'or the like, which allow a second mounting position, so that an alternative mounting plane 102' results. This results in a plurality of orientations of the vertical. In this case, the position of the outlet is chosen so that the distance between the intersection plane and outlet plane for at least two orientations is large in the above sense. This is achieved in the example shown, in which the angle 122 is about 45 °.

The abovementioned design rules are analogously applied to the second space 22 and the outlet of the return 64 provided therein into the second space.

The following Fig. 3 to Fig. 6 deal with embodiments in which the outlet is below the intersection level and thus in operation below the lubricant surface. These solutions are based on the gear chamber of the vacuum pump Fig. 1 explained.

It shows Fig. 3 a shaft 230 having a shaft axis 212 and a synchronizing gear 250 mounted thereon, and a spin structure 260. This dive at least part of its rotational movement under the lubricant surface 216 and thus lubricant with it, which is subsequently detached by centrifugal force and thereby distributed in the space 220. In particular, it reaches the synchronizing gear and a rolling bearing 232 which rotatably supports the shaft.

During operation of the vacuum pump, a pressure gradient arises at least temporarily such that fluid flows through the rolling bearing into the side facing away from the synchronizing wheel along the shaft. This flow is desirable because it causes a pressure equalization between the space and the suction chamber. However, lubricant is entrained from the rolling bearing, resulting in Lubricant leakage can lead. The following means reduce this considerably. A piston ring 276 forms a bottleneck between the shaft and housing and acts as a throttle. In the flow path behind the piston ring a centrifugal edge 274 is provided on the shaft, are centrifuged on the lubricant by centrifugal forces from the shaft. In the region of this centrifugal edge, the shaft is surrounded by a catching chamber 270, in which the centrifuged lubricant is collected and supplied to the return 254. The catching chamber has a substantially conical boundary wall 272 at least over part of its circumference. The diameter of the cone increases with increasing distance to the rolling bearing. Centrifugal edge and conical boundary wall are arranged to each other so that centrifuged lubricant hits the boundary wall. This design causes the impinging lubricant to move in a preferred direction along the boundary wall and not be reflected back directly toward the shaft. The lubricant is brought together in the direction of the return. In the flow direction of the catching chamber follows another acting as a throttle piston ring 278th

The return 254 comprises a catching chamber outlet 260, which receives the lubricant from the catching chamber. Through this Fangkammerauslauf the lubricant enters the next part of the return, the drain chamber 262. With respect to the vertical 200 deepest point of this drain chamber, a drain passage 266 is connected through which lubricant expires from the drain chamber and passes back into the lubricant filling, where leaves the return through the outlet 258. Through this outlet an outlet plane 208 is set, the surface normal is formed by the vertical. The spin structure defines the point of intersection 206 through the lowest point of its orbit, the surface normal of which is also formed by the vertical. The distance 210 between these two planes is chosen to be large. This is accomplished by placing the spout near the housing bottom 222 of the room 220 is arranged. Thus, it is in operation far below the lubricant surface 216. "Large distance" and "far" are to be understood here that is achieved by the position of the drain that lubricant, which is in the drain channel, when evacuating catch chamber and drain chamber not to is sucked into the catching chamber by the amount of lubricant present between the intersection plane and outlet plane builds up a back pressure.

Preferably, the distance of the planes is at least half, advantageously two-thirds, the distance between the intersection plane and a lowermost point of the inner wall of the space-limiting housing 222.

The discharge chamber is arranged above the point of intersection, in particular such that it is located above the lubricant surface 216 during operation of the vacuum pump. This has the effect that the foam resulting from the lubricant present in the drainage channel 266 can not rise up into the catching chamber but expands in the drainage chamber. In an advantageous development, the volume of the return between the shaft and the intersection plane is twice the volume between the outlet and the intersection plane. This can be further improved if three or four times is achieved. In a simple embodiment, the volume of the drain chamber 262 is at least twice the volume of the drain passage 266. The drain chamber may be configured as a recess in the housing which is closed by a chamber lid 264. The drainage channel can be designed inexpensively as a pipe.

A further education shows Fig. 4 in a schematic representation. The shaft 230 is surrounded by a catching chamber 270 ', to which in relation to the vertical 200 lower part of a drain chamber 262' is formed. Their cross section decreases in the direction of the intersection plane 206 and reaches above this the smallest Value. The drain chamber is at this point in the flow channel 266 'over, which ends in the outlet 258'. This determines the outlet plane 208, wherein the intersection plane and outlet plane in the aforementioned sense have a large distance 210. A shield 280 is disposed on the lower end of the drain channel relative to the vertical. This shield closes the outlet 258 'such that the drainage channel is closed opaque in the direction of the vertical. As a result, ascending foam can not reach the drainage channel directly in this direction.

In an advantageous development of this idea, the outlet is arranged such that it opens in the direction of rotation 218 of the centrifugal structure. This prevents lubricant from flowing through the flow generated by the centrifugal structure into the outlet.

The schematic illustrations after FIGS. 5 and 6 provide training that take into account the existence of two returns.

The arrangement after Fig. 5 has a first shaft 330 and a second shaft 328. A return 354 allows the return of lubricant from the first shaft to the lubricant fill, a second return 356 from the second shaft. The returns lead to one another at the junction 364, so that the lubricant quantities conducted in both are continued through the common drainage channel 366. This ends in the outlet 358. The volumes of the drainage channel and the return lines are advantageously dimensioned to one another in such a way that lubricant, which is located between the intersection plane 206 and the outlet 358, can foam up in the direction of the vertical 200 without reaching the corrugations. By this arrangement, a small lubricant leakage is achieved with few components and thus in a cost effective manner. It may make sense between the intersection plane and the node one

Provide drain chamber 362, which provides additional space for expansion of foam. Out of the too Fig. 3 described reasons, it makes sense to arrange the outlet in the aforementioned sense near the bottom of the gear chamber 322.

The arrangement after Fig. 6 has a first shaft 330 and a second shaft 328. A return 354 and a second return 356 are provided to return lubricant from the shaft. Between the first wave and intersection plane 206 and between the second wave and the intersection plane, a drain chamber 362 and a second drain chamber 380 are provided in the recirculation. A connection 382 connects each of the points of intersection of the closest points of the drainage chambers together. The connection has an outlet 358 on the side of the intersection point facing away from the waves. This is in an advantageous development on which, based on the vertical 200, farthest from the point of intersection point is arranged. The outlet is arranged in the aforementioned sense near the bottom of the gear chamber 322.

The design forms described with reference to FIGS. Can be combined with one another. The invention has been described on a single-stage vacuum pump, but it is generally applicable to twin-shaft vacuum pumps, even to multi-stage vacuum pumps. Their pistons may have a two- or multi-leaf Wälzkolbenprofil or designed as a claw or screw structure.

Claims (11)

A vacuum pump (1) having a mounting means (6) defining a vertical direction of gravity (100; 200) which is the surface normal to a mounting plane, a shaft (30; 28; 230; 330; 328) having a shaft axis (112; 212), a space (20,22; 220) serving to receive a lubricant charge (72; 74), a centrifugal structure (60,70; 260) disposed on the shaft for distributing lubricant in the space, an oil return (54; 254; 354; 356), which allows the return of lubricant into the room and has an outlet (58; 258; 258 '; 358) opened in the space,
characterized in that a discharge plane (108; 208) arranged in relation to the direction of gravity below the shaft includes the outlet and is parallel to the assembly plane, an intersection plane (106, 206) includes the lowest point (104) reached with respect to the direction of gravity during operation of the centrifugal structure and parallel to the mounting plane and - The distance (110, 210) between the exit plane and the intersection plane is large. Vacuum pump according to claim 1, characterized in that the angle (122) of a line (120) extending through the outlet (58) and shaft axis (112) to the assembly plane is more than 0 °, preferably at least 10 °. Vacuum pump according to claim 1 or 2, characterized in that the outlet between the intersection plane (106) and one of the shaft axis and parallel to the mounting plane parallel wave plane (118) is arranged and a first volume (114) is at least twice a second volume (116), wherein - The first volume of a housing (10), outlet plane (108) and intersection plane (106) and - The second volume is located on the side facing away from the first volume of the intersection plane and is bounded by the housing (10) and the intersection plane. Vacuum pump according to claim 1, characterized in that - The outlet plane (108; 208) on the side facing away from the shaft of the intersection plane (106; 206) is arranged and - the volume of the return between the shaft and intersection plane is at least twice the volume between the outlet and the intersection plane. Vacuum pump according to claim 4, characterized in that the volume of the return between the shaft and the intersection plane is at least partly from a discharge chamber (262, 362, 380) and the volume between the outlet and the intersection plane is formed by a tube (266; 266 '; 366). Vacuum pump according to claim 4 or 5, characterized in that the outlet comprises a shield (280) which shields the spout. Vacuum pump according to claim 6, characterized in that the shielding the outlet in a rotational direction (218) of the centrifugal structure opens. Vacuum pump according to claim 4 to 7, characterized in that it comprises a second shaft (28; 328) with a second return (356) and return and second return are interconnected and have a common outlet (358). Vacuum pump according to claim 8, characterized in that return and second return in the flow direction are connected to each other before the outlet. Vacuum pump according to one of the preceding claims, characterized in that the shaft is surrounded by a catching chamber (270). Vacuum pump according to one of the preceding claims, characterized in that the mounting means allows a plurality of orientations of the vertical and the distance (110; 210) is large for at least two orientations.

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