CN106662107B

CN106662107B - Claw type pump

Info

Publication number: CN106662107B
Application number: CN201580047420.8A
Authority: CN
Inventors: 彼得·伯奇; 克莱夫·滕纳
Original assignee: Laibao Co Ltd
Current assignee: Laibao Co Ltd
Priority date: 2014-09-05
Filing date: 2015-08-27
Publication date: 2020-01-10
Anticipated expiration: 2035-08-27
Also published as: DE202014007117U1; CN106662107A; TWI626379B; KR20170053665A; EP3189236A2; JP6643323B2; WO2016034485A3; TW201621167A; WO2016034485A2; JP2020056409A; JP2017527735A

Abstract

A claw pump is disclosed having two rotor shafts (14), each supporting a plurality of rotors (10, 12). In a preferred embodiment, the rotor shaft (14) is formed in one piece with the associated rotor (10, 12). The rotor shaft (14) is arranged together with the rotors (10, 12) in a pump housing (16, 18), wherein a plurality of pump stages are formed by the pump housing and the respective rotor pair (10, 12). To simplify assembly, the rotor shaft (14) is formed in one piece with the associated rotor (10, 12), and the pump housing is formed in two parts. In a preferred embodiment, the parting plane (24) of the pump housing (16, 18) passes transversely across the rotor shaft (14).

Description

Claw type pump

Technical Field

The invention relates to a claw pump comprising a plurality of pump stages.

Background

Claw pumps of this type are described, for example, in US 5/049,050 and US 8/308,458. The multistage claw pump comprises two rotor shafts on which rotors with claw profiles are arranged. Thus, each rotor profile includes one or more claw members with associated claw member recesses. The transfer of the medium is performed by two cooperating rotors rotating in opposite directions, wherein the claw members of one rotor engage the recesses of the other rotor. In a multistage claw pump, radial suction and radial discharge with respect to the longitudinal direction of the rotor shaft will occur for each stage. In the pump housing surrounding the rotor shaft and the rotor of the claw pump, corresponding channels are arranged for diverting the fluid discharged radially from a pump stage so that it will be sucked in radially again by the next pump stage. The respective claw rotors are arranged on the shaft by, for example, press fitting. The shafts are arranged in a multipart housing and are supported in the housing via oil-lubricated rolling bearings. In order to synchronize the two shafts, each shaft is provided with a gear. Due to the multipart design of the housing and the required connection of the individual rotor elements to the shaft, many occurring tolerances have to be compensated. Thus, the assembly process is performed in a stepwise manner. Thus, within the first housing part, a rotor shaft comprising the first pump stage (i.e. two respective rotors) will be arranged. Subsequently, the partition wall will be offset onto the two rotor shafts, thereby forming the first pump stage. Corresponding disks or spacers ("spacers") have to be used to compensate for tolerances, if necessary. To form the next stage, the latter two rotors and the latter housing portion will be offset onto the shaft. Also here, corresponding components are required to compensate for tolerances. Therefore, the assembly process of the claw pump including a plurality of stages is troublesome. Further, accurate synchronization between the two axes is required. Since this is achieved via the mechanical transmission since lubrication of the transmission is required. This, in turn, requires the arrangement of seals between the transmission and the correspondingly oil-lubricated rolling bearing and the pump stage. As a result, the costs of production and assembly are further increased.

Disclosure of Invention

It is an object of the present invention to provide a claw pump, in particular comprising a plurality of pump stages, wherein the costs for producing and assembling the pump are significantly reduced.

According to the present invention, the above object is achieved by the following features.

The claw pump of the present invention comprises two rotor shafts, each carrying a plurality of rotors. The two rotor shafts are arranged parallel to each other within the pump housing. By means of the pump housing, for each pump stage, a pump chamber is formed in which the rotor is arranged. According to a preferred embodiment, each rotor comprises two claw members and two claw member recesses. For transferring fluid, one claw member of one rotor will cooperate with a recess of the other rotor, respectively. According to the invention, the pump housing is designed in such a way that the separating plane of the pump housing extends in the longitudinal direction of the rotor shaft. In particular, the parting plane of the pump housing is arranged in a longitudinal center plane of the two shafts. This arrangement has the advantage that both shafts can be placed in a housing part together with the correspondingly provided rotor. Thus, the assembly process will no longer be performed with the step of one pump stage being installed after the other. Preferably, the pump stages are of a two-part design, so that the rotor shaft together with the rotor can be placed in the first pump stage as a complete structural assembly, and the pump housing will then be closed by mounting the second part of the pump housing. The assembly process of the claw pump will thereby be significantly simplified.

Preferably, the partition wall arranged between adjacent pump chambers is of two-part design. The parting plane of the partition wall is arranged in a plane extending in the longitudinal direction of the rotor shaft. In particular, the parting plane at the at least one partition wall coincides with the parting plane of the pump housing.

The partition wall and the side wall of the pump chamber of the optionally first and/or last pump stage are preferably provided with recesses which are open in the direction of the parting plane. The recesses are intended for receiving and respectively passing through the rotor shaft in the assembled state. For a particular preference, the recess is a substantially semicircular recess, so that the rotor shaft can be placed in the recess in a simple manner. Further, it is preferred that the at least one partition wall fixedly connected to one of the two housing parts is of one-piece ("onepiece") design. In particular, the two housing parts and the partition wall, or alternatively the side walls forming the pump chamber accommodating the first and/or last pump stage, may be of one-piece design. This may for example be a one-piece cast element.

According to a further preferred embodiment, the partition walls of respectively adjacent pump stages form connecting channels adapted to connect adjacent pump stages to each other. The provision of such a connecting channel in the partition wall represents a separate invention which is independent of the design of the pump housing, in particular of the two stages. In particular, the arrangement of the connecting channel in the intermediate wall has the advantage that such a connecting channel is easier to produce than in a pump housing of a closed pump stage. Thus, unlike the prior art, the connecting channels between the pump stages extend substantially axially relative to the rotor shaft. Thus, according to the invention, the respective inlets and outlets of the pump stages are arranged axially instead of radially as in the prior art.

According to a particularly preferred embodiment of the connecting channel, there is an opening in the direction of the partition wall. This is particularly beneficial in relation to providing a two-part pump housing, which preferably comprises a one-piece partition. Arranging the connecting channel so that these parting faces open towards the partition wall can have the advantage that the connecting channel is produced in a simple manner. In the case of a two-part pump housing, the connecting channel can be produced, for example, by milling or the like, wherein the milling tool can be directed substantially perpendicularly to the separating surface. In the connecting channel of this design, it is not necessary to provide the partition wall with a hole extending parallel to the axis of the rotating shaft.

According to a further preferred embodiment of the invention, the connecting channels are arranged in such a way that they are at least partially open in the direction of the opening occupying the, in particular, semi-circular shape of the rotor shaft. Thereby, the generation of the connection channel is further simplified. In the assembled state, the connecting channel is therefore at least partially closed off by the rotor shaft, except for small gaps.

According to a further preferred embodiment, the inlet and the outlet of the connecting channel arranged in the partition wall are arranged on different sides of the separating surface. Thus, in case the rotor shaft is arranged e.g. horizontally, the inlet is arranged on the centre plane of the rotor shaft and the outlet is arranged below the centre plane. It is therefore particularly preferred that the inlet and the outlet are formed in different housing parts, in particular in one of the two housing parts, respectively.

According to a particularly preferred embodiment of the invention, the inlets and/or outlets of the connecting channels are arranged in such a way that they are completely closed, partially closed or completely open by the associated rotor, depending on the respective rotor position. The associated rotor is one of the two rotors of the rotor pair of each pump stage, into and/or from which the medium flows in and/or out of the region of the pump stage. In the preferred embodiment, it is particularly advantageous that in one rotor position the inlet and/or outlet openings are completely closed. This can be achieved in a simple manner, since the respective openings are arranged in the separating wall and thus the openings have a side wall of the rotor extending across them. Thus, a good sealing of the inlet and/or outlet may be achieved. The sealing is quite good due to the small gap and the relatively large radial coverage. In order to achieve a good tightness and thus a compression from the first pump stage and preferably from the first pump stage to the second to the last pump stage, it is preferred that the cross section of the inlet and/or the outlet decreases from the first pump stage in the direction of the second to the last pump stage. The reduction may be provided in a continuous or stepwise manner. The cross-section may become smaller due to compression. Preferably, the inlet and/or outlet of the last stage has a cross-section larger than the cross-section of the second to last pump stages. In this way, the noise development of the pump can be reduced.

According to a further preferred embodiment of the invention, the arrangement and the respective orientation of the claw members and the claw recesses are the same in at least two pump stages and preferably in all pump stages. In particular, in at least two pump stages and preferably in all pump stages, each comprises a rotor having the same rotor profile. In this particularly preferred embodiment, the rotors differ from each other only in their axial width. This has the significant advantage that the rotor shaft and preferably all associated rotors can be provided in a one-piece design according to a particularly preferred embodiment of the invention. In addition to the advantage of simplified machining, this also allows less stringent requirements on the accuracy of the synchronization. The one-piece design of the rotor shaft in relation to the rotor can be considered as an independent invention, independent of the design of the housing. The combination of the two inventions is particularly preferred, since the one-piece design of the rotor shafts with rotors has the advantage that they can be placed in correspondingly formed housing halves. Because of the one-piece design of the rotor together with the rotor shaft, assembly-related tolerances will not occur, which have to be compensated for each pump stage. In particular, machining and assembly tolerances are prevented from potentially adding to each other.

Alternatively, on the rotor shaft, respective rotary pistons can be arranged as the first and/or last pump stage. In this modification it is preferred that the rotor shaft is formed in one piece, while the other rotors are designed as claw-type rotors, and that only the rotors formed as rotary pistons will be arranged on the rotor shaft, e.g. press them into place.

According to a particularly preferred embodiment of the invention, the two rotor shafts are arranged in the pump housing by means of grease-lubricated rolling bearings. In this way, the risk of contamination of the transport fluid due to oil lubrication can be avoided. No oil invades into the pump stage. Preferably, the synchronization device is thus also protected from oil. The synchronization device is used for synchronizing two shafts rotating relative to each other. According to a preferred embodiment, the oil-free synchronization of the two shafts is performed by means of belts and/or chains. Thus, there is no need to provide a gear transmission or at least two meshing gears that would have to be oil lubricated.

By an alternative to the mechanical synchronization means, it is also possible to drive the two shafts separately by separate motors, in particular electric motors, wherein the two motors are preferably synchronized with each other by an electric synchronization unit. It would also be possible to use force-less transmission devices (which may also include gears) because they do not need to be oiled due to the force-less transmission design.

The invention further relates to a rotor shaft unit for a vacuum pump, which can be considered independently as an invention and which, according to a preferred embodiment, can be used in a claw pump according to the invention. The rotor shaft unit according to the present invention includes a plurality of rotors supported by a rotor shaft. The rotor and the rotor shaft are formed in one piece. Preferably, as described above in connection with a claw pump, the rotors are designed in such a way that the rotors (preferably all rotors) have the same rotor profile. Thus, according to a particularly preferred embodiment, the rotors differ from each other only in their axial width.

It is particularly preferred that the one-piece rotor shaft is machined to a continuous cast profile, preferably an extruded profile. By machining into a continuous casting profile, a one-piece rotor shaft with a rotor can be machined in a simple manner. This is particularly possible because according to a preferred embodiment all rotors have the same rotor profile. Since a continuous cast profile can be machined with high precision, the profile can be processed essentially only by creating a gap between two adjacent rotors during milling. The machining process of the rotor shaft unit is therefore considerably cheaper than the machining and assembly of the individual rotors, which would have to be mounted on the shaft.

The machining of the rotor shaft unit therefore comprises the following basic machining steps:

first, an extrusion profile is produced, for example, in an extrusion molding process. Here, the outer contour of the entire extruded product preferably corresponds to the rotor contour. In the next step, an intermediate portion between adjacent rotors is created. This may be performed, for example, by a milling process. Here, the intermediate portion has such a depth that the shaft connecting two adjacent rotors will remain. Subsequently, bearing points may be created, for example at both ends of the shaft. In case the synchronization of the two rotor shaft units produced in this way is effected by means of a belt, chain or the like, a gear wheel may be arranged on the shaft in order to guide the chain or belt. Gears may also be used to establish a connection with the motor. The one-piece design of the rotor shaft unit has the advantage in particular that no added tolerances with respect to one another will occur and inexpensive machining will be possible.

In the claw pump of the invention comprising a rotor shaft unit having such a one-piece design, the assembly process is particularly simple and therefore inexpensive. Specifically, the assembly process includes the following basic steps:

in a first step, a one-piece rotor shaft unit (i.e. a rotor shaft formed in one piece with the rotor) is to be inserted into the first housing half. This insertion is performed into a recess, in particular of semicircular shape, provided in the separating wall. In this respect, it is particularly preferred, as mentioned above, that the housing halves do already comprise a separating wall as well. In a next step, the second housing half may be mounted and the two housing halves may be connected. The vacuum-tight connection can be realized, for example, by gluing. Depending on whether the synchronization unit is arranged inside the housing, the belt or chain is placed on a (preferably pre-mounted) gear or the like before or after the connection of the two housing halves.

In particular, since there are no added tolerances, the assembly process may be performed in the manner described above. In particular, the synchronization via two rotor shafts, for example toothed belts, chains or the like, will allow oil-free synchronization.

As a result of the preferably highly accurately symmetrical rotor machining, the smoothing process will be simple and require only little time.

Both the above-described machining method and the assembly process for the rotor shaft are considered independent inventions.

The multistage claw pump according to the invention can be equipped with all pump stages which are arranged axially behind one another, so that the compression increases continuously in the axial direction from one stage to the next. A central pump inlet may also be provided, with the pump stages extending in both directions therefrom. Here again, the pump stages are arranged axially on the same shaft, however, the opposite pumping direction will be achieved. Thus, in the dual exhaust pump described, the common inlet is located in the middle of the pump and the two outlets are located on the two outer sides of the pump.

The invention will be explained in more detail below by means of a preferred embodiment of a claw pump.

Drawings

In the drawings:

fig. 1-3 show schematic representations of pump stages of a claw pump in different positions, an

Fig. 4 shows a schematic representation of a housing half.

Detailed Description

The claw pump according to the invention comprises a plurality of pump stages arranged axially behind one another, wherein fig. 1 to 3 show a schematic cross-sectional view of one pump stage. These figures show that

rotors

10, 12 with the same pump stages, which are located in different positions, respectively, form a rotor pair. The two

rotors

10, 12 are each formed in one piece with a rotor shaft 14. The rotor shaft 14 is arranged in a pump housing formed by two

housing halves

16, 18. The

pump housings

16, 18 together with the

rotors

10, 12

form pump chambers

20, 22, the orientation of which will vary depending on the position of the

rotors

10, 12.

In this arrangement, the two

housing halves

16, 18 will be formed in such a way that the parting plane 24 extends in the longitudinal direction of the shaft 14. Here, the parting plane 24 is arranged at the level of the central plane of the two shafts 14.

As seen in the direction of view of fig. 1-3, a partition wall 26 is arranged behind both

rotors

10, 12. The intermediate wall forms an obstacle towards the pump stage, which in the embodiment shown is the preceding pump stage in the pumping direction. In the partition 26, a connecting channel is arranged, which is shown in general terms in fig. 1 to 3 by means of an arrow 28. The fluid to be pumped will flow into said connecting channel 28 through an outlet 30, which in the illustration of fig. 1-3 is arranged at the rear side of the partition wall 26. The fluid will then flow into the shown pump stage through an inlet 32, which in fig. 1-3 is arranged on the front side of the partition wall 26.

However, only when the two

rotors

10, 12 are in the position shown in fig. 2 does fluid flow into the inlet chamber 22 through the connecting channel 28 and the inlet 32. In this position, the inlet 32 is at least partially open, thus allowing fluid to rush into the intake chamber 22. At the same time, fluid will be transferred from the chamber 20 to the inlet and outlet. The outlet is arranged in a partition wall, which in fig. 1-3 is arranged in front of the shown rotor.

By the opposite rotation of the two rotors as indicated by the two arrows 32, a transport of the medium and a compression of the medium due to the reduced chamber volume is achieved. The

rotors

10, 12 include known claw profiles. In each rotor, the profile comprises two claw recesses 38.

In the section of the housing half 16 shown in fig. 4, two successive pump stages 40, 42 are partially visible. Here, the axial width of stage 40 is wider than the axial width of the subsequent stage 42, which will increase the compression of the transport medium. Two successive pump stages 40, 42 are separated by a partition 26 arranged in the separating plane 24. The partition 26 comprises two

recesses

44, 46 which open towards the parting plane 24. The two

recesses

44, 46 are intended to receive the two rotor shafts 14. Below the recess 44 seen in fig. 4, the partition 26 comprises the inlet 32 of the pump stage 42. Depending on the position of the rotor 10 (fig. 2), fluid will flow into the chamber 22 through the inlet 32. The inlet 32 is connected to the connecting channel 28. The channel first extends from the inlet 32 perpendicularly to the side 48 of the partition 26. Thereafter, preferably, in the middle with respect to the thickness of the partition wall 26, as seen in fig. 4, the channel 28 (a partial section 28a thereof) extends upward. The second casing half includes an outlet 30 higher than the recess 46 on a corresponding second wall of the pumping stage 40. The outlet 30 is connected to the

channels

28, 28a, corresponding to the inlet 32. In the upper part of the separating wall formed by the second housing half, a channel is thus formed in a corresponding manner. The connecting

channels

28, 28a are thus formed in a simple manner by placing the two

housing halves

16, 18 on top of one another.

A particular advantage of the exemplary embodiment of the connecting

channel

28, 28a shown in fig. 4 is that the machining will be simple, since the channel can be easily created, for example, by the use of an end mill. The channel can always be accessed from the top side 50 of the separating wall 26.

For the assembly of a claw pump, the rotor shaft 14, which is preferably machined in one piece with the

rotors

10, 12, will be placed from above (as seen in fig. 4) into the

recesses

44 and 46 of the separating wall. In the resulting arrangement, the rotor shaft 14 will always close a portion of the respective connecting channel 28.

Subsequently, the second casing half will be mounted such that the portions 28a of the connecting channel will be arranged on top of each other and a continuous connecting

channel

28, 28a will be formed between two adjacent pump stages 40, 42.

The other stages are formed in a corresponding manner, wherein the width of the pump stages 40, 42 extending in the longitudinal direction 52 of the rotor shaft 14 will decrease in the pumping direction.

Claims

1. A claw pump comprising:

two rotor shafts, each carrying a plurality of rotors,

each rotor comprises two claw members and two claw member recesses,

thereby a plurality of rotor pairs are provided, each forming a pump stage, wherein in each pump stage the claw members of one rotor cooperate with corresponding claw member recesses of the other rotor, and

a pump housing defining at least one pump chamber for each pump stage,

it is characterized in that the preparation method is characterized in that,

the pump housing has a separating surface extending in the longitudinal direction of the rotor shaft;

a partition is arranged between adjacent pump stages of the two-part design, in which partition a connecting channel is provided for connecting the respective adjacent pump stages to one another, which connecting channel is partially closed by the rotor shaft.

2. The claw pump according to claim 1, wherein said pump housing is of two-part design.

3. A claw pump according to claim 1, characterised in that the parting plane of the partition wall extends in the longitudinal direction of the rotor shaft.

4. A claw pump according to claim 3, characterised in that the partition wall comprises a recess which opens out to the parting plane and which is provided for accommodating the rotor shaft.

5. A claw pump according to claim 2 or 4, characterised in that the partition is formed integrally with the respective one of the two-part designs of the pump housing.

6. A claw pump according to claim 1, characterised in that the connecting channel opens out to the separating surface.

7. A claw pump according to claim 3, characterised in that the inlet and outlet of the connecting channel are arranged on different sides of the separating surface.

8. A claw pump according to claim 7, characterised in that the inlet and outlet of the connection channel are formed in two-part designs of different pump housings, respectively.

9. A claw pump according to claim 3, characterised in that the inlet and/or outlet of a connecting channel is completely closed, partially closed or completely open by the appurtenant rotor, depending on the rotor position.

10. A claw pump according to claim 9, characterised in that the inlet and/or outlet is designed in such a way that the cross-section decreases from the first pump stage to the second to the last pump stage.

11. A claw pump according to claim 10, characterised in that the inlet and/or outlet is designed in such a way that the cross section decreases continuously.

12. A claw pump according to claim 1, characterised in that the arrangement of the claw members and/or claw recesses is the same in at least two pump stages.

13. A claw pump according to claim 12, characterised in that the arrangement of the claw members and/or claw recesses is the same in all pump stages.

14. A claw pump according to claim 1, characterised in that the rotors of different pump stages differ in axial width.

15. A claw pump according to claim 1, characterised in that the rotor shaft and rotor are in a pre-assembled state before being arranged in a two-part pump housing.

16. A claw pump according to claim 1, characterised in that both rotor shafts and the associated rotors are formed in one piece.

17. A claw pump according to claim 1, characterised in that on the two rotor shafts respective rotors have been arranged, which are designed as rotary pistons for forming rolling piston stages.

18. A claw pump according to claim 1, characterised in that the two rotor shafts are supported in the pump housing by grease-lubricated rolling bearings.

19. A claw pump according to claim 1, characterised in that an oil-free synchronisation device is provided for synchronisation of the two rotor shafts.

20. A claw pump according to claim 1, characterised in that the two rotor shafts are connected to each other via a belt and/or chain for synchronisation.

21. A claw pump according to claim 1, characterised in that the two rotor shafts are each driven by a separate motor, the two rotor shafts being synchronized with each other via an electrical synchronization unit or via a non-power transmission gear.

22. Rotor shaft unit for a vacuum pump, in particular for a claw pump according to claim 1, comprising:

a rotor shaft carrying a plurality of rotors,

it is characterized in that the preparation method is characterized in that,

the rotor and the rotor shaft are formed in one piece.

23. Rotor shaft unit according to claim 22, characterised in that the rotors have the same rotor profile.

24. Rotor shaft unit according to claim 22 or 23, characterised in that the rotor forms a pump stage of a claw pump.

25. Rotor shaft unit according to claim 24, characterised in that the rotor shaft together with the rotor is machined to a continuous cast profile.

26. Rotor shaft unit according to claim 24, characterised in that the rotor shaft together with the rotor is processed into a continuous extruded profile.

27. Rotor shaft unit according to claim 26, characterised in that for the processing of rotors with different widths, a clearance is provided in the extrusion profile.