EP2836722B1 - Vacuum-type rotary slide pump - Google Patents

Description

The invention relates to a vacuum rotary vane pump.

Rotary vane vacuum pumps have a suction chamber arranged in a housing. A rotor is arranged eccentrically within the housing. Two or more slides are usually connected to the rotor in slide slots. As a result of the centrifugal force, the slides are pressed against an inner wall of the pump chamber while the rotor is rotating. To generate a vacuum, a suction opening of the vacuum rotary vane pump is connected to the room to be vacuumed. Due to the eccentricity of the rotor and the changing size of the chambers formed between the slides, the medium is conveyed through one or more discharge channels. For lubrication and to ensure good sealing of the slide on the inner wall of the pump chamber, a certain amount of oil is always present in the pump chamber to form an oil film. Since the ejected medium is thus mixed with oil, the at least one ejection channel usually runs from the pump chamber into an oil chamber.

If the vacuum rotary vane pump is suddenly stopped, for example due to a failure, the result is that the pump chamber overflows with oil via the lubricant supply. This leads to an increased torque as well as increased noise development during the next Starting the pump. Furthermore, the slide can be damaged due to the increased torque. There is also the risk that oil will enter the room to be vacuumed and cause damage there. It is therefore necessary that the suction chamber of the vacuum rotary vane pump is brought to atmospheric pressure after it has been stopped in order to prevent the lubricant from flowing in.

For this it is over U.S. 3,301,474 known to provide a bore provided with a valve device which is connected to the suction chamber. This is relatively complex, since a valve device to be controlled separately, which must meet high tightness requirements, has to be provided.

It is also off EP 1 899 608 B1 a vacuum rotary vane pump is known in which a compensation channel is connected to the discharge channel. There is essentially atmospheric pressure at the compensation channel. The compensation channel is arranged in a flange of the pump housing and covered by a valve plate of the valve device. This solution by the applicant can prevent the pump chamber from filling up when the vacuum rotary vane pump fails or is switched off. If the vacuum rotary vane pump fails or is switched off, air is sucked into the pump chamber through the compensation channel, so that after a short time atmospheric pressure prevails in the pump chamber or the part of the pump chamber connected to the discharge channel.

The object of the invention is to provide a covered groove in the flange to develop an alternative solution that can be retrofitted, if necessary, more cost-effectively and / or in existing pumps.

The object is achieved according to the invention by the features of claim 1.

In the vacuum rotary vane pump according to the invention, the pump chamber is connected to an oil chamber via a discharge channel, a valve device being arranged between the oil chamber and the discharge channel. The valve device serves to prevent a backflow of medium, d. H. usually a mixture of oil and air from the oil chamber to prevent the pump chamber. Furthermore, at least one compensation channel is provided which connects the discharge channel to an area in which there is essentially atmospheric pressure. The compensation channel is preferably connected to an air space of the oil chamber, the air space of the oil chamber being the area of the oil chamber which is above the oil bath and in which air, which may have been enriched with oil, is essentially present.

By providing such a compensation channel in connection with a valve device arranged between the oil chamber and the discharge channel, the medium is pressed out of the pump chamber into the discharge channel during operation, whereby the medium, which is usually a mixture of gas such as air and oil acts, passes through the valve device into the oil chamber. Part of the oil present in the medium is pressed into the equalization channel or sucked in by it and thus seals it off. This ensures that no fresh air is sucked in via the compensation channel during operation, or that air with ambient pressure gets into the discharge channel. If the vacuum rotary vane pump fails or if the vacuum rotary vane pump is deliberately stopped, the oil is pressed out of the capillary and air is sucked in through the equalization channel due to the lower pressure prevailing in the pump chamber. This leads to a rapid pressure equalization in the pump chamber, so that the pump chamber is quickly brought to atmospheric pressure. As a result, the pump chamber does not fill up with oil via the lubricant supply. This avoids the disadvantages of an increased torque at the next start and any damage to the slider that this might cause. Also an oil or This prevents lubricant from entering the room to be vacuumed. The period of time to equalize the pressure in the pump chamber is very short.

According to the invention, the compensation channel is integrated into the valve device. This makes it possible, for example, to manufacture the valve device independently of the housing, in particular a groove provided in the housing. This has the advantage that a valve device configured according to the invention and having the compensation channel can be used for differently configured rotary vane pumps. It is also possible to retrofit existing rotary vane pumps by simply replacing the valve device.

According to the invention, the valve device has a valve plate which closes the discharge channel and which interacts with a spring element. The spring element exerts a closing force on the valve plate. The spring element is preferably also plate-shaped and has an elastic material for generating the spring force.

Since the at least one compensation channel is integrated in the valve device according to the invention, the valve plate has a connecting opening connected to the discharge channel. The connection opening opens into the compensation channel. The cross-sectional area of the connection opening and preferably also of the compensation channel is preferably selected as a function of the viscosity of the lubricant in such a way that the at least one compensation channel forms a capillary channel into which oil is sucked in during operation. This closes the compensation channel during operation.

Another problem with vacuum rotary vane pumps is that when the rotor rotates at the limit, an increased speed Noise development can be determined. To reduce noise, the housing has a small opening in the compression area through which air can flow. This creates an oil emulsion, which can reduce noise levels. Since the air supply is very imprecise and therefore the degree of emulsion of the oil is also imprecise, the development of noise can only be reduced slightly.

A controlled and defined emulsification of the oil is also achieved by providing the compensation channel. As described, the compensation channel is at least partially filled with oil, while the medium is conveyed from an area of the pump chamber between two adjacent slides into the discharge channel. If the following slide then subsequently passes the opening of the discharge channel connected to the pump chamber, the oil supply stored in the compensation channel is conveyed into this chamber. A small amount of air is sucked in from the equalization duct, which leads to the emulsion of the oil. Depending on the lubricant used, good emulsification of the lubricant can be ensured in particular through the number and shape of the compensating channels. The provision according to the invention of at least one equalizing channel thus also leads to a noise reduction in the rotational speed limit ranges of the vacuum rotary vane pump.

The small cross-sectional area of the at least one equalization channel ensures that only a small amount of air gets into the pump. In particular, the amount of oil temporarily stored in the equalization channel (s) and the amount of air sucked in can be determined by the number and cross-sectional area and the shape of the at least one equalization channel.

In a particularly preferred development of the invention, an intermediate element is provided between the valve plate and the spring element of the valve device. The at least one compensation channel is formed by the intermediate element. The intermediate element preferably delimits the compensation channel laterally and below, so that a compensation channel opening is formed in an upper region of the intermediate element. The compensation channel opening is connected to the oil chamber, the connection being made in the area of the oil chamber in which there is gas or air. The lower area is thus the area opposite the upper area, the lower area preferably being arranged in the oil bath of the oil chamber.

It is also preferred that the compensation channel is delimited by the valve plate and the spring element. As a result, a versatile closed channel is formed which has an equalizing channel opening in the upper area and is closed in the lower area.

The intermediate element is preferably designed in such a way that it partially surrounds the connection opening. The intermediate element is preferably U-shaped. If several compensation channels are provided, several individual intermediate elements or a common intermediate element can also be provided. Here, the individual intermediate elements are preferably U-shaped or, in the case of a common intermediate element, the intermediate elements have corresponding slots or openings that form the compensating channels. The at least one intermediate element can be connected to the valve plate and / or the spring element or an intermediate part arranged between the spring element and the intermediate element. This can be done, for example, by gluing or welding. It is also possible for the intermediate element to be designed in one piece with the valve plate and / or the spring element. In particular, a one-piece design with the spring element made from an elastic plastic can take place. Preferably that is Intermediate element also made of elastic material in order to be able to guarantee a good seal. In particular, the at least one intermediate element is made from elastomeric plastic. This can be a separate intermediate element that forms one or more compensating channels.

In a further preferred alternative embodiment, the at least one compensation channel is provided in the valve plate. Here, for example, a slot or a groove can be provided in the valve plate. The at least one equalization channel formed in this way is in turn open at the top and has a corresponding equalization channel opening which, in particular, opens into the oil chamber in an area in which gas or air is present. To form the compensation channel, a bore could also be provided in the valve plate, with the provision of a slot or a groove being preferred for manufacturing reasons. If a groove is provided, it is open in one direction. This opening of the groove can be closed by a housing wall, such as a flange of the housing. It is also possible that the opening of the groove points in the other direction and is then closed by the spring element or an intermediate part. When a slot is provided in the valve plate, it is open in both directions and is then closed on one side by the housing wall and on the other side by the spring element or the intermediate part.

Although the above invention is essentially described on the basis of an ejection channel which is connected to an equalizing channel, it is also possible for the pump chamber to be connected to the oil chamber via several ejection channels which preferably run parallel to one another. The multiple discharge channels can either be closed with separate valve devices, it being preferred to provide a common valve device. This valve device can have a valve plate with several finger-like attachments, from each finger-like approach an ejection channel is closed. In this embodiment, the spring element is preferably designed accordingly. At least one of the plurality of discharge channels is connected to a compensation channel integrated in the valve device according to the invention. Preferably, several, in particular all, discharge channels are connected to one equalization channel. A common compensation channel can be provided for several discharge channels or a separate compensation channel for each discharge channel.

The discharge channel is preferably opened and closed with the aid of the valve tongue or the valve plate. For this purpose, the valve plate is made of an elastic, resilient material. According to the invention, a particularly good sealing of the valve plate can be achieved in that the area of the valve plate which seals the discharge channel is located in an oil bath, so that an additional contact pressure is built up. Due to the increased tightness, a further and more efficient evacuation can be carried out.

The invention is explained in more detail below on the basis of preferred embodiments with reference to the accompanying drawings.

Fig. 1

eine schematische Schnittansicht einer ersten Ausführungsform einer Vakuum-Drehschieberpumpe,

Fig. 2

eine schematische Darstellung der Einzelteile der Ventileinrichtung der ersten Ausführungsform,

Fig. 3

eine schematische Schnittansicht einer zweiten Ausführungsform einer Vakuum-Drehschieberpump und

Fig. 4

eine schematische Darstellung der Einzelteile der Ventileinrichtung der zweiten Ausführungsform.

Show it:

Fig. 1

a schematic sectional view of a first embodiment of a vacuum rotary vane pump,

Fig. 2

a schematic representation of the individual parts of the valve device of the first embodiment,

Fig. 3

a schematic sectional view of a second embodiment of a vacuum rotary vane pump and

Fig. 4

a schematic representation of the individual parts of the valve device of the second embodiment.

A rotary vane vacuum pump ( Fig. 1 ) has a housing 10. A rotor 14 is arranged within the housing 10 in a suction chamber 12. In the exemplary embodiment shown, the rotor 14 has three slide slots 16, in each of which a slide 18 is arranged. The slide 18 is pressed by the rotation of the rotor 14 due to the centrifugal force against an inner wall 20 of the pumping chamber.

Via a suction opening 22, which is connected to the space to be evacuated, medium is sucked from the space to be evacuated into a first region 24 of the pumping space 12. The area 24 of the pump chamber 12 is delimited by two adjacent slides 18. A region 28 of the pump chamber 12 located in front of the region 24 in the direction of rotation 26 is reduced in size by the rotation of the rotor 14, so that the medium located therein is compressed. The medium is conveyed from the area 28 through an ejection channel 30 from the pump chamber 12 in the direction of an oil chamber 32.

The oil chamber 32 is attached to a flange 34 of the housing 10 of the vacuum rotary vane pump. The oil chamber 32 has an oil space or an oil bath 35 in which the oil supplied via the discharge channel 30, in particular together with the air removed from the space to be evacuated, collects.

An outlet opening 36 of the discharge channel 30 is closed with a valve device 38. In the particularly preferred exemplary embodiment shown, the valve device is an elastic valve plate 48 ( Fig. 2 ), which is fastened to the flange 34 of the housing 10 with the aid of a screw or nut 40, for example. It is particularly preferred in the area of the outlet opening 36 that To arrange valve plates 48 in an oil bath 42. For this purpose, a separate oil chamber is formed in the oil chamber 32 by an intermediate wall 44, the oil flowing in the direction of an arrow 47 when the oil chamber is filled. By providing an oil bath 42, pressure is exerted on a rear side of the valve plate, ie the side of the valve plate pointing in the direction of the oil bath 42. This increases the tightness of the valve device 38.

According to the invention, a compensation channel is integrated into the valve device 38.

In the first preferred embodiment of the invention ( Figs. 1 and 2 ) a compensation channel 50 is formed by an intermediate element 52. In a preferred embodiment, the intermediate element 52 is a U-shaped part made of elastic plastic. For the configuration of the three compensation channels 50 shown in the exemplary embodiment shown, the valve has a valve plate 48. The valve plate 48, which in the illustrated embodiment closes three discharge channels 30 running parallel to one another, has finger-shaped projections 54 for this purpose. These finger-shaped projections 54 pointing downward each have a connecting opening 56. The connection opening 56 represents a connection between the discharge channel 30 and the compensation channel 50. The intermediate elements 52 are arranged on the finger-shaped projections 54, it being possible, for example, to fix them by gluing. An intermediate part 58, which is part of the intermediate element, closes the front part of the respective compensation channels 50 pointing away from a flange surface 47. The intermediate part 58 is also fixed by the screw 46.

The valve device also has a spring element 60. This spring element, made in particular of elastic plastic material, causes the valve plate 48 to be pushed back and thus the discharge channels 30 to be closed. Both the intermediate part 58 and the spring element 60 have projections 62, 64 corresponding to the finger-shaped projections 54.

In the assembled state, the compensation channels 50 are thus delimited by the valve plate 48, the U-shaped intermediate elements 52 and the intermediate part 48. Compensation channels 50 are connected to discharge channels 30 via connection openings 56. Compensation channels 50 are connected to an air space 53 of oil chamber 32 via compensation channel openings 66, which are arranged in the upper region of the intermediate elements.

By rotating the rotor 14, a medium enriched with oil is conveyed from the area 28 in the direction of an arrow 68 into the discharge channel 30 during operation. As a result of the pressure, the valve plate 48 is pushed back so that the medium reaches the oil bath 42 or the oil chamber 32 in the direction of an arrow 70. A part of the oil is pressed into the compensation channels 50 and thus causes a seal.

As soon as the area 28 is essentially emptied, the oil supply present in the channels 50 is sucked into the discharge channel 30 together with a small amount of air, which is sucked in through the opening 66 from the air space 53 of the oil chamber 32. The entrainment of air emulsifies the oil and thus reduces noise.

When the pump is stopped, for example due to a failure, air is sucked from the air space 53 into the pump chamber 12 via the opening 66 and the compensation channels 50, so that a pressure equalization takes place and the pump chamber 12 is brought to essentially atmospheric pressure. This ensures that no or at most only small amounts of lubricant get into the pump chamber. This prevents the pump chamber 12 from filling up with lubricant.

Due to the oil flow or oil circulation in the area of the valve device 38, in particular the valve plate 48, it is ensured that no deposits form here. In particular, pollution is the Valve device 38 avoided. This avoids jamming of the valve device 38. Furthermore, a good seal is ensured and an influence of the valve tightness on the pump performance is avoided.

A second preferred embodiment ( Figs. 3 and 4 ) has the same components with the exception of the design of the valve device 38, so that they are identified by the same reference numerals. The mode of operation also corresponds to that above with reference to FIG Figs. 1 and 2 Function of the vacuum rotary vane pump described.

The in Figs. 3 and 4 The illustrated embodiment, the at least one compensation channel is integrated into the valve device 38 in such a way that a slot is provided in the valve plate 48 to form a compensation channel 72. This extends in the vertical direction over a large part of the valve plate, in particular into one of the finger-shaped projections 54. The connection between the discharge channel 30 and the compensation channel 72 takes place in the lower region 74 of the slot.

To design the compensation channel 72, the slot is limited laterally on the one hand by the valve plate 48 and on the other hand by the flange surface 47 and a correspondingly designed valve spring 60. In addition, between the valve spring 60 and the valve plate 48, an intermediate part corresponding to the intermediate part 58 ( Fig. 2 ) be provided. How the Figures 3 and 4 The rotary vane vacuum pump shown corresponds to that of the in Figs. 1 and 2 rotary vane vacuum pump shown.

Claims (13)

1. A vacuum rotary vane pump, comprising

   a housing (10) including a suction chamber (12),

   a rotor (14) eccentrically arranged in the suction chamber (12),

   vanes (18) slidably connected to the rotor (14),

   a discharge channel (30) connected to the suction chamber (12) and to an oil chamber (32),

   a valve means (38) arranged between the oil chamber (32) and the discharge channel (30) to prevent a backflow of medium from the oil chamber (32) into the suction chamber (12), wherein the valve means (38) closing the at least one discharge channel (30) is arranged in the area of the at least one discharge channel (30) in an oil bath (42), and wherein the valve means (38) comprises a valve plate (48) closing the at least one discharge channel (30), and a spring element (60) acting on the valve plate (48), and

   at least one compensating channel (50, 72) connected to the discharge channel (30) and substantially subjected to atmospheric pressure,

   wherein the at least one compensating channel (50, 72) is integrated into the valve means (38),

   characterized in that

   the valve plate (48) has a connecting opening (56, 74) which opens into the compensating channel (50, 72) and is connected to the discharge channel (30).
2. The vacuum rotary vane pump according to claim 1, characterized in that the compensating channel (50) is formed by an intermediate element (52) arranged between the valve plate (48) and the spring element (60).
3. The vacuum rotary vane pump according to claim 2, characterized in that the intermediate element (52) delimits the compensating channel (50) laterally and at the bottom, and that a compensating channel opening (66) is formed in the upper area.
4. The vacuum rotary vane pump according to claim 1, characterized in that the compensating channel (50) is further delimited by the valve plate (48) and the spring element (60) or an intermediate part (58).
5. The vacuum rotary vane pump according to any one of claims 2 to 4, characterized in that the intermediate element (52) partially surrounds the connecting opening (56) and is preferably U-shaped.
6. The vacuum rotary vane pump according to any one of claims 2 to 5, characterized in that the intermediate element (52) is connected to the valve plate (48) and/or the spring element (60) and/or the intermediate part (58), or is integrally formed with the valve plate (48) and/or the spring element (60) and/or the intermediate part (58).
7. The vacuum rotary vane pump according to any one of claims 2 to 6, characterized in that the intermediate element (52) is made of an elastic material, in particular elastomeric plastic.
8. The vacuum rotary vane pump according to claim 1, characterized in that the compensating channel (72) is provided in the valve plate (48).
9. The vacuum rotary vane pump according to claim 8, characterized in that the compensating channel (72) is provided as a slit or groove in the valve plate (48), the slit or groove being closed laterally by the spring element (60) or an intermediate part (58) and/or a housing wall (47) of the housing (10), wherein the slit or the groove is preferably open to the top.
10. The vacuum rotary vane pump according to any one of claims 1 to 9, characterized in that the compensating channel (50, 72) is closed during the operation of the rotary vane vacuum pump with oil.
11. The vacuum rotary vane pump according to any one of claims 1 to 10, characterized in that the compensating channel (50, 72) is formed as a capillary channel.
12. The vacuum rotary vane pump according to any one of claims 1 to 11, characterized in that a plurality of discharge channels (30), preferably being parallel to one another, are provided between the suction chamber (12) and the oil chamber (32) and are preferably closed by a common valve means (38), wherein at least one, preferably several, and particularly preferred all discharge channels (30) are connected to one compensating channel (50, 72).
13. The vacuum rotary vane pump according to any one of claims 1 to 12, characterized in that the at least one compensating channel (50, 72) is connected to an air space (53) of the oil chamber (32).

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