EP3921515A1

EP3921515A1 - Multistage pump body and multistage gas pump

Info

Publication number: EP3921515A1
Application number: EP19704770.7A
Authority: EP
Inventors: Theodore Iltchev; Sergio DESSI; Stéphane VARRIN
Original assignee: Ateliers Busch SA
Current assignee: Ateliers Busch SA
Priority date: 2019-02-06
Filing date: 2019-02-06
Publication date: 2021-12-15
Anticipated expiration: 2039-02-06
Also published as: EP3921515C0; CN113396272B; WO2020160770A1; BR112021014163A2; CA3128727A1; JP7390384B2; US20220127962A1; PL3921515T3; CN113396272A; JP2022522108A; KR20210124385A; AU2019427999A1; KR102612571B1; US12116895B2; EP3921515B1; ES2951642T3

Abstract

A multistage pump body comprises a first pumping chamber (20) and a second pumping chamber (21). A connecting duct (26a) puts an outlet (27) of the first pumping chamber (20) into communication with an inlet (28) of the second pumping chamber (21). A leaktight conduit (40) is provided for the circulation of a cooling liquid. The connecting duct (26a) is a lateral duct of the multistage pump body. A heat-conducting wall (33) partially delimits the connecting duct (26a) and has an external surface (34) on the outside. At least one portion of the connecting duct (26a) passes between this external surface (34) of the heat-conducting wall (33) and the leaktight conduit (40).

Description

MULTI-STAGE PUMP BODY AND MULTI-STAGE GAS PUMP

Technical field of the invention

The present invention relates to a multistage pump body, as well as to a multistage pump, which may in particular be a vacuum pump. In the following and in the appended claims, the term "pump" covers pumps for driving a gas, vacuum pumps and also compressors, while the expression "pump body" denotes a part which may belong to to such a pump for driving a gas, to such a vacuum pump or to such a compressor.

State of the art

In a known manner, a multistage pump is a pump comprising several successive pumping chambers, which connecting conduits connect to each other so that the gas compressed in a pumping chamber other than the last one is led to the inlet of the pump. next pumping chamber.

The gas compression carried out in each pumping chamber results in the release of heat for the discharge of which various cooling devices have been proposed.

In European patent EP 2 626 562 B1, a multistage pump is described in which, during its journey between two successive pumping chambers, the gas flows along a plate provided with cooling fins and intended to evacuate the heat to the outside atmospheric air, by simple natural convection.

Another solution for removing the heat given off during the compression of a gas in a multistage pump uses heat exchangers, in each of which the gas is cooled during its journey between two. successive pumping chambers. Document JP 2001 -27190 proposes cooling based on this other solution.

It is also known to cool a multistage pump by circulating a cooling liquid such as water. In US Pat. No. 8,573,956 B2, the cooling circuit passes between the last pumping chamber and the penultimate pumping chamber, then below the other pumping chambers. In JP 2014-55580, a rectilinear tube for the flow of a cooling liquid passes either in a connecting pipe for the gas between two pumping chambers, or between two consecutive pumping chambers.

In JP 2001 -20884 as in JP 2- 95792 (JPH 0295792 A), cooling by means of a coolant is also provided. This cooling is an external cooling insofar as the cooling liquid passes around the pumping chambers and around the connecting ducts connecting these pumping chambers to one another.

The cooling of the multistage pumps described in the aforementioned documents and patents has an efficiency which is not completely satisfactory.

Brief description of the invention

The invention is at least aimed at improving the efficiency of the removal of heat which is generated by the compression of gas in a multistage pump body of a multistage pump when the latter is in operation.

According to the invention, this object is achieved by means of a multistage pump body, comprising at least a first pumping chamber, a second pumping chamber, a connecting duct putting in

communicating an outlet of the first pumping chamber with a entrance to the second pumping chamber, as well as a sealed gallery for the circulation of a cooling liquid. The connecting duct is a lateral duct of the multistage pump body which comprises at least one heat conduction wall partially delimiting the connecting duct and having an external surface on the outside. At least a portion of the connecting duct passes between this external surface of the heat conduction wall and the sealed gallery.

Each of the first and second pumping chambers is designed to receive at least one member capable of producing a downstream movement of gas. As it is compressed in each of the first and second pumping chambers, the pumped gas heats up. As it passes through the connecting duct, this gas is cooled via the heat conduction wall, which is itself cooled by ambient atmospheric air. In this way, a first cooling of the multistage pump body takes place by natural convection and by radiation to the ambient atmospheric air. At the same time, a second cooling of the multistage pump body is produced by a transfer of heat to the cooling liquid circulating in the sealed gallery. Double cooling of the multistage pump body according to the invention therefore takes place. As it improves cooling, the invention enables better pumping efficiency, which is an advantage. In particular, by improving pumping efficiency, the maximum pumped flow rate can be increased. In other words, the invention has the advantage of making it possible to obtain an increase in the maximum flow rate that a pump can pump.

The multistage pump body defined above may incorporate one or more other advantageous features, individually or in combination.

combination, in particular among those defined below.

Advantageously, at least a portion of the sealed gallery passes between the connecting duct and at least one of the first and second pumping chambers. When this is the case, the coolant circulating in the sealed gallery cools both the connecting duct and at least one of the first and second pumping chambers, which results in even more efficient cooling.

Advantageously, at least a portion of the sealed gallery passes between the first pumping chamber and the second pumping chamber. When this is the case, the cooling liquid circulating in the sealed gallery effectively cools the first and second pumping chambers.

Advantageously, the multistage pump body comprises at least one heat conduction partition separating the connecting duct and the sealed gallery from one another. Such a heat conduction partition effectively removes heat from the connecting duct to the cooling liquid circulating in the sealed gallery.

Advantageously, the multistage pump body comprises at least one heat conduction partition separating the sealed gallery and the first pumping chamber from one another. Such a heat conduction partition effectively removes heat from the first pumping chamber to the cooling liquid circulating in the sealed gallery.

Advantageously, the sealed gallery partially envelops the first pumping chamber and / or the second pumping chamber.

When this is the case, the cooling of at least one of the first and second pumping chambers is very efficient.

Advantageously, the sealed gallery comprises at least one inlet for the cooling liquid and at least one outlet for the cooling liquid. Advantageously, the multistage pump body comprises at least one axial passage for a rotary shaft, a segment of this axial passage connecting the first and second pumping chambers. Advantageously, the multistage pump body has a first side and a second side opposite the first side with respect to the axial passage, the connecting duct passing at the level of the first side of the multistage pump body, the multistage pump body delimiting another duct connection putting the outlet of the first pumping chamber into communication with the inlet of the second pumping chamber, this other connecting duct passing through the second side of the multistage pump body.

Advantageously, the multistage pump body has a third side and a fourth side opposite to the third side with respect to the axial passage, the outlet of the first pumping chamber being located at the level of the third side of the multistage pump body, the inlet of the second pumping chamber located at the fourth side of the multistage pump body.

Advantageously, an inlet of the first pumping chamber is located at the level of the fourth side of the multistage pump body, an outlet of the second pumping chamber located at the level of the third side of the multistage pump body.

Advantageously, the connecting duct is a first connecting duct, the multistage pump body comprising a third pumping chamber and a second connecting duct which is a duct placing an outlet of the second pumping chamber in communication with an inlet of the pump. third pumping chamber, the heat conduction wall being a first heat conduction wall, the multistage pump body comprising at least one second heat conduction wall, this second heat conduction wall partially delimiting the second connecting duct and having an external surface on the outside, at least a portion of the second connecting duct passing between this external surface of the second heat conduction wall and the sealed gallery. When this is the case, the gas is cooled both during its passage through the first connecting duct and during its passage through the second connecting duct. Advantageously, the multistage pump body comprises two ends crossed by the or each axial passage, the external surface of the heat conduction wall forming part of a lateral surface extending between the two ends of the multistage pump body. Advantageously, the heat conduction wall comprises two opposite main surfaces and a constant thickness or not between these two opposite main surfaces, one of which is the external surface of the heat conduction wall.

Since this is a lateral duct, the connecting duct communicates the outlet of the first pumping chamber with the inlet of the second pumping chamber without passing between the first and the second pumping chamber.

Advantageously, over most of its length, the connecting duct has a cross section which is elongated in a direction substantially parallel to the axial passage.

The subject of the invention is also a multistage pump which comprises a multistage pump body as defined above. The outer surface of the heat conduction wall is on the outside of the pump. The multistage pump defined above can incorporate one or more other advantageous characteristics, individually or in combination, in particular among those defined below.

Advantageously, the multistage pump comprises at least a first rotor to produce a downstream movement of gas in the first pumping chamber, at least a second rotor to produce a

displacement of gas downstream in the second pumping chamber and a rotary shaft carrying the first and second rotors. Advantageously, the multistage pump is a lobe pump or a lobe pump or a gear pump and, advantageously, it comprises at least one other first rotor in the first pumping chamber, at least one other second rotor in the second pump chamber. pumping and another rotating shaft carrying the other first and second rotors, the first rotor and the other first rotor being able to produce a

movement of gas downstream in the first pumping chamber by being driven in opposite directions, the second rotor and the other second rotor being able to produce a movement of gas downstream in the second pumping chamber by being driven in opposite directions.

Brief description of the drawings

Other advantages and characteristics will emerge more clearly from the description which follows of a particular embodiment of the invention given by way of non-limiting example and shown in the accompanying drawings, among which:

- Figure 1 is a side view of a multistage pump according to one embodiment of the invention,

- Figure 2 is a sectional view along the line II-II of Figure 1 and shows the same multistage pump as this Figure 1,

- Figure 3 is a perspective view of a multistage pump body which is according to one embodiment of the invention and which is part of the multistage pump of Figures 1 and 2,

- Figure 4 is a longitudinal sectional view along the vertical plane IV of Figure 3 and shows the same multistage pump body as in Figure 3, - Figure 5 is a longitudinal sectional view along the horizontal line VV of Figure 4 and shows the same multistage pump body as Figures 3 and 4,

- Figure 6 is a cross-sectional view along the line VI-VI of Figure 4 and shows the same multistage pump body as Figures 3 and 4,

- Figure 7 is a cross-sectional view along line VII-VII of Figure 4 and shows the same multistage pump body as Figures 3 and 4, - Figure 8 is a cross-sectional view along line VIII- VIII of figure 4 and shows the same multistage pump body as figures 3 and 4,

- Figure 9 is a cross-sectional view along the line IX-IX of Figure 4 and shows the same multistage pump body as Figures 3 and 4,

- Figure 10 is a cross-sectional view along the line X-X of Figure 4 and shows the same multistage pump body as Figures 3 and 4, and

- Figure 11 is a cross-sectional view along the line XI-XI of Figure 4 and shows the same multistage pump body as Figures 3 and 4.

Description of a preferred mode of the invention

A multistage pump 1 according to one embodiment of the invention is shown alone in FIG. 1. It comprises a multistage pump body 2, each end of which carries a housing 3 provided with one of two synchronized electric motors 4 and 5. with each other. As can be seen in Figure 2, the multistage pump 1 is a lobe pump. The invention is not however limited to lobe pumps. For example, a pin pump or a gear pump may be in accordance with the invention. The multistage pump 1 comprises two rotary shafts 8, which are driven in rotation in opposite directions, one by the electric motor 4 and the other by the electric motor 5. Each rotary shaft 8 carries three rotors, each of which is part of. a pair of complementary rotors 9. Each rotor 9 has several lobes, of which there are four in the example shown. The number of lobes of the rotors 9 could however be different from four.

The multistage pump body 2 is shown on its own in FIG. 3. It consists of two housings 1 1 and 12, each of which has a discontinuous fixing flange 13. Visible only in Figure 1, screws 14 mounted at the mounting flanges 13 secure the housings 1 1 and 12 to each other by tightening.

The multistage pump body 2 has an inlet 16 for a cooling liquid, as well as two outlets 17 for this same cooling liquid. As can be seen in Figure 4, the multistage pump body 2 delimits several successive pumping chambers, which are aligned in a direction parallel to the rotary shafts 8 and which are a first pumping chamber 20, a second pumping chamber. pumping 21 succeeding the first pumping chamber 20 and a third pumping chamber 22 succeeding the second pumping chamber 21.

In the example shown, the pumping chambers 20 to 21 are 3 in number, but their number could be different from 3.

As can be seen in FIG. 2, one of the pairs of complementary rotors 9 is located in the first pumping chamber 20. De Similarly, a pair of complementary rotors is in each of the pumping chambers 21 and 22. For the sake of clarity, the two rotary shafts 8 and the rotors 9 of the multistage pump 1 are not shown in Figures 4 to 1. 1. As can be seen in FIG. 4, the suction 23 of the multistage pump 1 is extended by the inlet of the first pumping chamber 20, while the outlet of the third pumping chamber 22 is extended via the discharge 24 of the multistage pump 1.

The casing 1 1 partially delimits the first pumping chamber 20, which one of the casings 3 closes at the level of a face at the end 2a of the multistage pump body 2. The casing 11 and the casing 12 together delimit the second pumping chamber 21. The casing 12 partially delimits the third pumping chamber 22, which one of the housings 3 closes at the level of one face at the end 2b of the multistage pump body 2. Seals compressed in grooves provide sealing between the casings 11 and 12. They are referenced 25 in Figure 5.

As can be seen in Figures 4 and 5 considered together, two connecting conduits 26a and 26b symmetrical to each other connect the outlet 27 of the first pumping chamber 20 to the inlet 28 of the second pumping chamber 21. The conduits 26a and 26b are the first connecting conduits. A pair of second connecting conduits 29a and 29b symmetrical to one another connect the outlet 30 of the second pumping chamber 21 to the inlet 31 of the third pumping chamber 22. In FIG. 4, the arrow C symbolizes the flow of gas from the suction 23 to the discharge 24.

The first connecting ducts 26a and 26b, as well as the second connecting ducts 29a and 29b, are lateral ducts of the multistage pump body 2. Each of the first connecting ducts 26a and 26b is partially delimited by a side wall which is a heat conduction wall 33 having an outer surface 34 outside the multistage pump 1. The heat conduction walls 33 are first heat conduction walls. Each of the second connecting conduits 29a and 29b is partially delimited by one of two side walls which are second heat conduction walls 36 each having an external surface 37 on the outside of the multistage pump 1.

The multistage pump body 2 delimits a sealed gallery 40 for the circulation of the cooling liquid which can be, for example, water.

As can be seen in Figure 6, the sealed gallery 40 communicates with the outlets 17, through which the cooling fluid present in this sealed gallery can be discharged.

As can be seen in Figure 7, the sealed gallery 40 partially surrounds the first pumping chamber 20.

As can be seen in Figure 9, the sealed gallery 40 partially surrounds the second pumping chamber 21.

As can be seen in Figure 10, the sealed gallery 40 comprises a distribution chamber 40a, into which the inlet 16 opens, which allows the sealed gallery 40 to be supplied with cooling fluid.

As can be seen in Figure 11, the sealed gallery 40 partially surrounds the third pumping chamber 22.

As can be seen in Figures 5 to 7, the sealed gallery 40 passes between the first pumping chamber 20 and each of the first connecting ducts 26a and 26b. A heat conduction partition 42 delimits

partially the first connecting duct 26a and the sealed gallery 40, which it separates from one another. Another heat conduction partition 42 partially delimits the first connecting duct 26b and the sealed gallery 40, which it separates from one another. A heat conduction partition 43 delimits partially the first pumping chamber 20 and the sealed gallery 40, which it separates from one another.

When the pump 1 is operating, the gas sucked by this pump 1 is compressed in the first, second and third pumping chambers 20 to 22, during which it heats up.

The heat of the gases passing through the first connecting ducts 26a and 26b is removed both by the heat conduction walls 33 and by the heat conduction partitions 42. A first cooling takes place due to a heat transfer. to the ambient air by radiation and natural convection, at the level of the external surfaces 34 of the heat conduction walls 33. A second cooling is carried out at the level of the heat conduction partitions 42, by the cooling liquid circulating in the sealed gallery 40. The gases passing through the first connecting ducts 26a and 26b therefore undergo the accumulation of two simultaneous cooling, which takes place on the two wide sides of each first connecting duct 26a or 26b.

In addition to cooling the heat conduction partition 42, the cooling liquid circulating in the sealed gallery 40 cools the heat conduction partition 43 and therefore the first pumping chamber 20 by means of this heat conduction partition 43 .

As can be seen in Figures 5 and 9, the sealed gallery 40 passes between the second pumping chamber 21 and each of the second connecting conduits 29a and 29b. A heat conduction partition 45 partially delimits the second connecting duct 29a and the sealed gallery 40, which it separates from one another. Another heat conduction partition 45 partially delimits the second connecting duct 29b and the sealed gallery 40, which it separates from one another. A heat conduction partition 46 partially delimits the second pumping chamber 21 and the sealed gallery 40, which it separates from one another. The heat of the gases passing through the second connecting ducts 29a and 29b is discharged both through the heat conduction walls 36 and through the heat conduction partitions 45. Cooling takes place by natural convection and heat transfer to the heat. 'ambient air at the level of the outer surfaces 37 of the heat conduction walls 36. Another cooling is carried out at the level of the heat conduction partitions 45, by the cooling liquid circulating in the sealed gallery 40. The gases passing through the second connecting ducts 29a and 29b therefore undergo the accumulation of two simultaneous cooling, which takes place on the two wide sides of each second connecting duct 29a or 29b.

In addition to cooling the heat conduction partition 45, the cooling liquid circulating in the sealed gallery 40 cools the heat conduction partition 46 and therefore the second pumping chamber 21 via this heat conduction partition 46 A portion of the sealed gallery 40 is located in the partition wall 50 between the first pumping chamber 20 and the second pumping chamber 21, between which it passes, which results in improved cooling of these first and second chambers. pumping chamber 20 and 21. A portion of the sealed gallery 40 is located in the partition wall 51 between the second pumping chamber 21 and the third pumping chamber 23, between which it passes, which improves the cooling of these second and third pumping chambers 21 and 22.

In Figures 6 to 10, two axial passages each for one of the rotary shafts 8 are referenced 53 and pass right through the partition wall 50 and the partition wall 51.

The invention is not limited to the embodiment described above. In particular, a multistage pump body according to the invention may have only a single axial passage 53 for a single rotary shaft 8, for example in the case where it forms part of a vane pump.

Claims

1. Multistage pump housing, comprising at least:

¨ a first pumping chamber (20),

¨ a second pumping chamber (21), ¨ a connecting duct (26a) placing an outlet in communication

(27) of the first pumping chamber (20) with an inlet (28) of the second pumping chamber (21), and

¨ a sealed gallery (40) for the circulation of a cooling liquid, characterized in that the connecting duct (26a) is a lateral duct of the multistage pump body which comprises at least one heat conduction wall (33) partially delimiting the connecting duct (26a) and having an external surface (34) on the outside, at least a portion of the connecting duct (26a) passing between this external surface (34) of the heat conduction wall (33 ) and the waterproof gallery (40).

2. Multistage pump body according to claim 1, characterized in that at least a portion of the sealed gallery (40) passes between the connecting duct (26a) and at least one of the first and second pumping chambers ( 20, 21). 3. Multistage pump body according to any one of claims 1 and 2, characterized in that at least a portion of the sealed gallery (40) passes between the first pumping chamber (20) and the second pumping chamber ( 21).

4. Multistage pump body according to any one of the preceding claims, characterized in that it comprises at least one heat conduction partition (42) separating the connecting duct (26a) and the sealed gallery (40) from one another.

5. Multistage pump body according to any one of the preceding claims, characterized in that it comprises at least one heat conduction partition (43) separating the sealed gallery (40) and the first pumping chamber (20) l 'one from the other.

6. Multistage pump body according to any one of the preceding claims, characterized in that the sealed gallery (40) partially envelops the first pumping chamber (20) and / or the second pumping chamber (21).

7. Multistage pump body according to any one of the preceding claims, characterized in that the sealed gallery (40) comprises at least one inlet (16) for the cooling liquid and at least one outlet (17) for the cooling liquid. cooling. 8. Multistage pump body according to any one of the preceding claims, characterized in that the multistage pump body comprises at least one axial passage (53) for a rotary shaft (8), a segment of this axial passage (53) connecting the first and second pumping chambers (20, 21). 9. Multi-stage pump body according to any one of the preceding claims, characterized in that it has a first side and a second side opposite to the first side with respect to the axial passage (53), the connecting duct (26a) passing at the level of the first side of the multistage pump body, the multistage pump body delimiting another connecting duct (26b) placing the outlet (27) of the first pumping chamber (20) in communication with the inlet (28) of the second pumping chamber (21), this other connecting duct (26b) passing through the second side of the multistage pump body. 10. Multistage pump body according to any one of the preceding claims, characterized in that the connecting duct (26a) is a first connecting duct (26a), the multistage pump body

comprising a third pumping chamber (22) and a second connecting pipe (29a) which is a pipe placing an outlet (30) of the second pumping chamber (21) in communication with an inlet (31) of the third chamber of pumping, the heat conduction wall (33) being a first heat conduction wall (33), the multistage pump body comprising at least one second heat conduction wall (36), this second heat conduction wall ( 36) partially delimiting the second connecting duct (29a) and having an external surface (37) on the outside, at least a portion of the second connecting duct (29a) passing between this external surface (37) of the second wall of heat conduction (36) and the sealed gallery (40). 11. Multistage pump, characterized in that it comprises a multistage pump body (2) according to any one of the preceding claims, the outer surface (34) of the heat conduction wall (33) being on the outside. of the pump.

12. Multistage pump according to claim 1 1, characterized in that it comprises at least a first rotor (9) for producing a downstream movement of gas in the first pumping chamber (20), at least a second rotor. to produce a downstream gas movement in the second pumping chamber (21) and a rotary shaft (8) carrying the first and second rotors. 13. Multistage pump according to any one of the claims

11 and 12, characterized in that it is a lobe pump or a lobe pump or a gear pump and in that it comprises at least one other first rotor (9) in the first pumping chamber (20) , at least one further second rotor in the second pumping chamber (21) and another rotary shaft (8) carrying the other first and second rotors, the first rotor and the other first rotor (9) being able to produce a movement of gas downstream in the first pumping chamber (20) while being driven in direction contrary, the second rotor and the other second rotor being able to produce a downstream movement of gas in the second pumping chamber (21) by being driven in opposite directions.