阅读说明：本技术 干式气体泵和多个干式气体泵的组 (Dry gas pump and group of a plurality of dry gas pumps ) 是由 T·伊尔切夫 S·瓦芮 D·穆勒 于 2019-03-14 设计创作，主要内容包括：干式气体泵包括：第一转子(1),该第一转子包括第一凸轮部分(1A)和第一螺杆(1B),以及第二转子(2),该第二转子包括第二凸轮部分(2A)和第二螺杆(2B)。外壳界定内部容积,第一螺杆和第二螺杆(1B,2B)以及第一凸轮部分和第二凸轮部分(1A,2A)共同定位在所述内部容积中。每个第一螺杆和第二螺杆(1B,2B)均包括沿其长度不可变的螺纹。该第一转子和第二转子(1,2)在相反方向上转动,并且以连续配置定位。在转子的第一配置中,第一凸轮部分和第二凸轮部分(1A,2A)、第一螺杆(1B)的一部分、第二螺杆(2B)的一部分以及外壳共同界定封闭的腔室(30)。在转子的第二配置中,腔室(30)具有比该第一配置更小的容量。在转子的第三配置中,腔室(30)在第一螺杆和第二螺杆(1B,2B)处完全移位,并且与凸轮部分隔离。(The dry gas pump includes: a first rotor (1) comprising a first cam portion (1A) and a first screw (1B), and a second rotor (2) comprising a second cam portion (2A) and a second screw (2B). The housing defines an interior volume in which the first and second screws (1B, 2B) and the first and second cam portions (1A, 2A) are co-located. Each of the first and second screws (1B, 2B) comprises a thread that is non-variable along its length. The first and second rotors (1, 2) rotate in opposite directions and are positioned in a sequential arrangement. In a first configuration of the rotor, the first and second cam portions (1A, 2A), a portion of the first screw (1B), a portion of the second screw (2B), and the housing together define an enclosed chamber (30). In a second configuration of the rotor, the chamber (30) has a smaller volume than the first configuration. In a third configuration of the rotor, the chamber (30) is fully displaced at the first and second screws (1B, 2B) and isolated from the cam portion.)

1. A dry gas pump comprising:

a first rotor (1) comprising a first cam portion (1A) and a first screw (1B),

a second rotor (2) comprising a second cam portion (2A) and a second screw (2B), an

A housing (3) in which the first and second rotors (1, 2) are rotationally mounted such that the first and second screws (1B, 2B) mesh and the first and second cam portions (1A, 2A) engage with each other,

the housing (3) defining an inner volume (14), the first and second screws (1B, 2B) and the first and second cam portions (1A, 2A) being co-located in the inner volume, at least one inlet (15) entering the inner volume (14) at the first and second cam portions (1A, 2A), at least one outlet from the inner volume (14) being located opposite the inlet (15) with respect to the first and second screws (1B, 2B),

characterised in that each of the first and second screws (1B, 2B) comprises a thread that is non-variable along its length, the first and second rotors (1, 2) rotating in opposite directions so as to be sequentially positionable in the following configuration:

-a first configuration in which the first and second cam portions (1A, 2A), a portion of the first screw (1B), a portion of the second screw (2B) and the housing (3) together delimit a closed chamber (30),

-a second configuration in which the chamber (30) is always delimited by the first and second cam portions (1A, 2A), a portion of the first screw (1B), a portion of the second screw (2B) and the casing (3), so that the chamber is closed and has a smaller capacity than the first configuration,

-a third configuration in which the chamber (30) is completely displaced at the first and second screws (1B, 2B) and is isolated from the cam portion at least by the helix (21) of the threads of the first screw (1B), the helix (23) of the threads of the second screw (2B) and the interruption formed by the intersection of the helix (21) of the first screw (1B) and the helix (23) of the second screw (2B), and

-a fourth configuration in which the chamber (30) is displaced at the downstream ends of the first and second screws (1B, 2B) and communicates with the outlet (16).

2. Dry gas pump according to claim 1, characterized in that the first and second cam parts (1A, 2A) comprise cams (20, 22), each cam extending through one of the spirals (21, 23) of the thread of the first and second screw (1B, 2B).

3. Dry gas pump according to claim 2, characterized in that the number of cams (20) of the first cam section (1A) is equal to the number of the spirals (21) of the thread of the first screw (1B) and the number of cams (22) of the second cam section (2A) is equal to the number of the spirals (23) of the thread of the second screw (2B).

4. Dry gas pump according to any of the preceding claims, characterized in that the outlet (16) is located at a distance from the first and second screws (1B, 2B).

5. A dry gas pump according to any one of the preceding claims, characterized in that the chamber (30) is one of a plurality of successive chambers (18, 25, 30, 31, 32, 33) which are jointly delimited by the first and second rotors (1, 2) and a housing (3).

6. Dry gas pump according to claim 5, characterized in that there are always two closed chambers in the successive chambers (18, 25, 30, 31, 32, 33) regardless of the respective angular position of the first and second rotors (1, 2).

7. Dry gas pump according to any of claims 5 and 6, characterized in that one of the successive chambers (18, 25, 30, 31, 32, 33) is a collection chamber (18) having the outlet (16) from the inner volume (14).

8. Dry gas pump according to claim 7, characterized in that the threads of the first screw (1B) and the threads of the second screw (2B) delimit helical grooves, the downstream ends of which are open and enter the collection chamber (18) regardless of the angular position of the first and second rotors (1, 2).

9. A dry gas pump according to any of the preceding claims, characterized in that the first rotor (1) is a male rotor and the second rotor (2) is a female rotor.

10. Dry gas pump according to any of the preceding claims, characterized in that the second rotor (2) comprises one more cam than the first rotor (1).

11. Dry gas pump according to any of the preceding claims, characterized in that the first rotor (1) comprises a number of cams of two and the second rotor (2) comprises a number of cams of three.

12. Dry gas pump according to any of the preceding claims, characterized in that the cross section of the first rotor (1), except its angular orientation, is the same at the first cam section (1A) and at the first screw (1B), while the cross section of the second rotor (2), except its angular orientation, is the same at the second cam section (2A) and at the second screw (2B).

13. Dry gas pump according to any of the preceding claims, characterized in that the first rotor (1) comprises at least two monolithic elements held together, which are a first monolithic element comprising at least the first screw (1B) and a second monolithic element comprising at least a part of the first cam portion (1A).

14. A set of dry gas pumps according to any of the preceding claims, wherein the first screw (1B) of a first dry gas pump of the set is identical to the first screw of a second dry gas pump of the set, the second screw (2B) of the first dry gas pump is identical to the second screw of the second dry gas pump, the first and second cam portions (1A, 2A) of the first dry gas pump have an axial dimension which is a first axial dimension, and the first and second cam portions (1A, 2A) of the second dry gas pump have an axial dimension which is a second axial dimension different from the first axial dimension.

Technical Field

The present invention relates to the field of pumping and compressing gases. More particularly, the present invention relates to a dry gas pump and a set of multiple dry gas pumps.

Background

One type of dry gas pump is a progressive cavity pump. A progressive cavity pump comprises two screws, each on one of two parallel axes of rotation, which are in mesh and driven in opposite directions. In the case of some mixing pumps, each screw is subordinated to a rotor which also includes a lobe portion, so that the screw pump and lobe pump are therefore combined, as is the case, for example, in US 7611340B 2.

In a screw pump, the screw flight may vary along the screw, thereby defining an internal compression ratio of gas between the upstream end of the screw and its downstream end. For example, the screw thread may be varied by means of a gradual or stepwise change in the pitch of each thread. Also in screw pumps, the number of turns of the thread can be varied along the screw, that is to say the length of the screw can be varied in order to modify the dynamic "tightness" and thus the final pressure or final vacuum obtained by the screw pump. In any case, the modification of the compression ratio requires, for each screw, the realization of a new screw form, whereas in the case of the screw pumps, the shape of the screws with variable flight is very complex and therefore very difficult to design and machine.

To modify the rated flow of a screw pump, the pitch of the upstream end of the screw and/or the bottom diameter of the flight, and therefore the crest diameter (flight profile height) of the flight, can be modified while maintaining the same rotational speed and the same pitch. These modifications must be kept within the limits of mechanical stability during rotation and within the limits of industrial processing possibilities. In any case, the variation of the nominal flow rate requires, for each screw, the realization of a new screw format, whereas in screw pumps the shape of the screws with variable flight is very complex and therefore very difficult to design and machine.

Disclosure of Invention

The present invention has at least the object of simplifying the design and/or creating a series of dry gas pumps with different compression ratios. More specifically, the invention has the object of creating a series of dry gas pumps with the flexibility and advantages of variable pitch screw pumps, but with rotors having a profile that is easier to design and/or machine, with the same or similar constraints in terms of volume, energy consumption, etc.

According to the invention, this object is achieved by means of a dry gas pump comprising: the first rotor includes a first cam portion and a first screw, the second rotor includes a second cam portion and a second screw, and a housing in which the first rotor and the second rotor are rotatably installed such that the first screw and the second screw are engaged and the first cam portion and the second cam portion are engaged with each other. The housing defines an interior volume in which the first and second screws and the first and second cam portions are co-located. At least one inlet enters the interior volume at a first cam portion and a second cam portion. The at least one outlet of the interior volume is positioned opposite the inlet with respect to the first screw and the second screw. Each of the first and second screws includes a thread that is non-variable along its length. The first and second rotors rotate in opposite directions so as to be sequentially positionable in the following configuration:

■ a first configuration in which the first and second cam portions, a portion of the first screw, a portion of the second screw, and the housing together define an enclosed chamber,

■ a second configuration in which the chamber is always bounded by the first and second cam portions, a portion of the first screw, a portion of the second screw, and the housing, such that the chamber is enclosed, and has a smaller volume than the first configuration,

■ a third configuration in which the chamber is fully displaced at the first and second screws and the chamber is isolated from the cam portion by at least the helix of the flight of the first screw, the helix of the flight of the second screw, and a break formed by the intersection of the helix of the first screw and the helix of the second screw, and

■ fourth configuration in which the chamber is displaced at the downstream ends of the first and second screws and is in communication with the outlet.

The first screw and the second screw have the function of blocking and opening the chamber. The first cam portion and the second cam portion have a function of performing compression. Therefore, the first screw and the second screw do not have a role of performing compression, and the flight of each of the first screw and the second screw is invariable in its length. For this reason, these first and second screws are not difficult to design and to produce compared to variable flight screws.

Further, the compression ratio is a function with respect to the first cam portion and the second cam portion. The compression ratio can be modified by adjusting the sizes of the first cam portion and the second cam portion in the axial direction. Starting from a given first screw and a given second screw, it is possible to construct a pump that does not have the same compression ratio, according to the axial dimensions of the cam portions associated with these first and second screws. Furthermore, the cam section is much less difficult to produce than a screw.

Thus, thanks to the present invention, a series of dry gas pumps with different compression ratios can be more easily designed and produced.

The dry gas pump defined above may comprise one or more other advantageous features, in particular including those defined below, alone or in combination.

Preferably, the first and second cam portions comprise cams, each cam extending through one of the helices of the threads of the first and second screws.

Preferably, the number of cams of the first cam portion is equal to the number of spirals of the thread of the first screw, and the number of cams of the second cam portion is equal to the number of spirals of the thread of the second screw.

Preferably, the outlet is located spaced apart from the first and second screws.

Preferably, the chamber is one of a plurality of successive chambers defined collectively by the first and second rotors and the housing.

Preferably, there are always two closed chambers in succession, regardless of the respective angular position of the first rotor and the second rotor.

Preferably, one of the successive chambers is a collection chamber having an outlet from the interior volume.

Preferably, the threads of said first screw and the threads of said second screw define helical grooves, the downstream ends of which are open and enter the collection chamber regardless of the angular position of the first rotor and the second rotor. In this case, the first screw and the second screw do not perform any compression. Heating of the gas due to compression of the gas occurs substantially at the first cam portion and the second cam portion. For this reason, it is easier to prevent the temperatures of the first and second screws from rising greatly in operation, thereby preventing significant deformation in these first and second screws due to expansion.

Preferably, one of the successive chambers is a suction chamber communicating with the inlet.

Preferably, the first rotor is a male rotor and the second rotor is a female rotor.

Preferably, the second rotor comprises one more cam than the first rotor.

Preferably, the number of the plurality of cams included in the first rotor is two, and the number of the plurality of cams included in the second rotor is three.

Preferably, the cross-section of the first rotor is identical at the first cam portion and at the first screw, except for its angular orientation, and the cross-section of the second rotor is identical at the second cam portion and at the second screw, except for its angular orientation.

Preferably, the first rotor comprises at least two unitary elements held together, the at least two unitary elements being a first unitary element comprising at least the first screw and a second unitary element comprising at least a portion of the first cam portion.

The invention also has the subject of a set of a plurality of dry gas pumps as defined previously. The first screw of the first dry gas pump of the group is identical to the first screw of the second dry gas pump of the group, the second screw of the first dry gas pump is identical to the second screw of the second dry gas pump, the first cam portion and the second cam portion of the first dry gas pump have an axial dimension that is a first axial dimension, and the first cam portion and the second cam portion of the second dry gas pump have an axial dimension that is a second axial dimension that is different from the first axial dimension.

Drawings

Further advantages and characteristics will appear more clearly from the description of a particular embodiment of the invention, represented by way of non-limiting example in the accompanying drawings, in which:

FIG. 1 is an axial cross-sectional view and schematic illustration of a dry gas pump according to one embodiment of the present invention;

FIG. 2 is a perspective view showing two component rotors of the pump of FIG. 1, and the shafts of these rotors have been omitted for simplicity;

FIG. 3 is a side and exploded view showing a single one of the two rotors of the pump of FIG. 1, and the shaft of the rotor shown omitted for simplicity;

FIG. 4 is a simplified view as in FIGS. 2 and 3, showing the same rotors as in FIG. 2, and the chambers partially defined by the rotors in the pump of FIG. 1, with the rotors viewed from one end;

FIG. 5 is a simplified perspective view as in FIGS. 2 and 3, showing the same rotor as in FIG. 2, and the chamber partially defined by the rotors in the pump of FIG. 1;

FIG. 6 is a perspective view showing one of the chambers seen in FIGS. 4 and 5;

FIG. 7 is a perspective view of the same chamber as in FIG. 6 but after, that is, at a time subsequent to the time at which the chamber is at as shown in FIG. 6;

fig. 8 is a perspective view of the same chamber as fig. 6 and 7 but after, that is, at a time after the time at which this chamber is as shown in fig. 7; and

fig. 9 is a graph showing the evolution of the capacity of the chambers of fig. 6 to 8 over time.

Detailed Description

In fig. 1, a dry gas pump according to an embodiment of the present invention includes a first rotor 1 and a second rotor 2, and the first rotor 1 and the second rotor 2 are installed in a housing 3 in such a manner that several parts remain assembled.

A plurality of bearings 5 support the shaft 6 of the first rotor 1 such that this first rotor 1 is at the axis of rotation X₁-X'₁And (4) upward rotation. A plurality of bearings 7 support the shaft 8 of the second rotor 2 so that this second rotor 2 is parallel to the rotation axis X₁-X'₁Of (2) a rotation axis X₂-X'₂And (4) upward rotation. In the sense of what is referred to herein and in the claims that follow, the axial direction is the direction parallel to the axis of rotation X₁-X'₁And X₂-X'₂Parallel to the axis of rotation X, and the axial dimension₁-X'₁And X₂-X'₂The dimension in the parallel direction.

One end of the shaft 8 is coupled with a motor 10 for driving the first and second rotors 1 and 2. Opposite to the motor 10, the shaft 8 of the second rotor 2 carries a toothed wheel 11 which meshes with a toothed wheel 12 carried by the shaft 6 of the first rotor 1. The toothed wheels 11 and 12 form a gear transmission with a gear ratio equal to 3/2 so that the first rotor 1 rotates faster than the second rotor 2.

The first rotor 1 comprises a first cam portion 1A and a first screw 1B, which follow each other in the axial direction without a distance between them. The second rotor 2 comprises a second cam portion 2A and a second screw 2B, which follow each other in the axial direction with no distance therebetween. The first cam portion 1A, the first screw 1B, the second cam portion 2A and the second screw 2B are all in the same internal volume 14, which is delimited by the housing 3, without being partitioned.

An inlet 15 for sucking in gas passes through the housing 3 and, at the first cam portion 2A and the second cam portion 2B, passes through the rotation axis X₁-X'₁And X₂-X'₂Into the interior volume 14. An outlet 16 for the discharge of the gases passes through the casing 3 and communicates with the internal volume 14 at a collection chamber 18 constituted by a downstream portion of the internal volume 14, which is located at the outlet of the first screw 1B and of the second screw 2B, that is to say, with respect to these first screw 1B and second screw 2B, opposite the first cam portion 1A and the second cam portion 2A.

The internal volume 14 is cylindrical at least at the first screw 1B and at the second screw 2B, and is constituted by a combination of two mutually penetrating rotating cylinders, the respective axes of which are the rotation axis X₁-X'₁And X₂-X'₂. At the first cam portion 1A and the second cam portion 2A, at least about the axis X of rotation₁-X'₁And X₂-X'₂On the opposite side of the plane of the inlet 15, the internal volume 14 is cylindrical in the same way. At the inlet 15, the downstream and lateral portions of the internal volume 14 may constitute a suction chamber where the internal volume 14 is laterally enlarged and forms the inlet 15.

Reference numeral 17 designates devices each of which effects a seal between the housing 3 and one of the shafts 6 and 8.

As can be seen from fig. 2, the first rotor 1 is maleAnd a rotor. The first cam portion 1A comprises a plurality of identical cams 20, and in the embodiment shown the number of cams 20 is two. The screw 1B comprises a thread formed by a helix 21, the number of said helices being the same as the number of cams 20 here. This thread is invariable over the entire length of the screw 1B. The pitch, mean diameter and profile of the thread, that is, along the axis of rotation X₁-X'₁The shape and size of the cross section of the thread of the axial plane of (a) is invariable over the entire length of the screw 1B. Each cam 20 extends through one of two identical helical lines 21. The number of cams 20 may be different from two. The same applies to the number of spirals 21.

The second rotor 2 is a female rotor. The second cam portion 2A comprises a plurality of identical cams 22, and in the embodiment shown the number of cams 22 is three. The screw 2B comprises a thread formed by a helix 23, the number of said helices being the same as the number of cams 22 here. This thread is not variable over the entire length of the screw 2B. The pitch, mean diameter and profile of the thread, that is, along the axis of rotation X₂-X'₂The shape and size of the cross section of the thread of the axial plane of (a) is invariable over the entire length of the screw 2B. Each cam 22 extends through one of three identical helical lines 23. The number of cams 22 may be different from two. The same applies to the number of spirals 23.

The first cam portion 1A engages with the second cam portion 2A. The first screw 1B is interlocked with the second screw 2B.

The cross section of the first rotor 1, except for its angular orientation, is the same at the first cam section 1A and the first screw 1B. In the same way, the cross section of the second rotor 2, except for its angular orientation, is the same at the second cam portion 2A and the second screw 2B.

As can be best seen from fig. 3, the first rotor 1 is assembled from a plurality of single elements, wherein the first single element comprises the first cam portion 1A, and wherein the second single element comprises the first screw 1B. The shaft 6 may be part of a first monolithic element of the first rotor 1, or may be part of a second monolithic element of the first rotor 1. Likewise, the third monolithic element of the first rotor 1 may constitute the shaft 6. The second rotor 2 is assembled from a plurality of single elements, wherein the first single element comprises the second cam portion 2A, and wherein the second single element comprises the second screw 2B. The shaft 8 may be part of a first unitary element of the second rotor 2 or may be part of a second unitary element of the second rotor 2. Likewise, a single element distinct from the first and second single elements of the second rotor 2 may constitute the shaft 8.

At any one time, the first rotor 1, the second rotor 2 and the housing 3 jointly define a plurality of successive chambers, some of which are visible in fig. 4 and all of which are visible in fig. 5. Among these successive chambers are the collection chamber 18, the suction chamber mentioned above and designated by the reference numeral 25 in fig. 4 and 5, and the chambers 30, 31, 32 and 33.

When the first rotor 1 and the second rotor 2 are in the configuration represented in fig. 4 and 5, the chambers 30, 31, 32 and 33 are closed. When the dry gas pump of fig. 1 is operated, the first rotor 1 and the second rotor are rotated in opposite directions as indicated by arrows in fig. 4. Thus, the chambers 30, 31, 32 and 33 evolve, which is illustrated by fig. 6 to 8, which show a single chamber 30 at successive instants.

When the first rotor 1 and the second rotor 2 are in the configuration represented in figures 4 and 5, the chamber 30 is as shown in figure 6. After a half turn and a third turn of the first rotor 1 and the second rotor 2, respectively, from the positions they had in fig. 3 and 4, the chamber 30 is shown in fig. 7. When the chamber is as shown in fig. 7, the chamber 30 has the shape and position of the chamber 31 in fig. 3 and 4. After one revolution and 2/3 revolutions of the first rotor 1 and the second rotor 2, respectively, from the positions they had in fig. 3 and 4, the chamber 30 is shown in fig. 8. When the chamber is as shown in fig. 8, the chamber 30 has the shape and position of the chamber 32 in fig. 3 and 4.

As will now be described, the evolution of the chamber 30 over time as the first and second rotors rotate continuously in opposite directions.

In fig. 6, the chamber 30 is closed at its downstream end, that is to say at P1, by the intersection of the spiral 21 and the spiral 23. Also in fig. 6, the first 1A and second 2A cam portions, a portion of the first screw 1B, a portion of the second screw 2B and the housing 3 together define a chamber 30 which reaches almost its maximum capacity.

The first rotor 1 and the second rotor 2 continue to rotate continuously in opposite directions starting from their positions in fig. 4 and 5. Thus, the first cam portion 1A and the second cam portion 2A reach a configuration from which they jointly reduce the volume of the chamber 30, the downstream end of which is still interrupted at P1 by the intersection of the spiral wire 21 and the spiral wire 23. In fig. 7, the chamber 30 is represented by the timing at which the first cam portion 1A and the second cam portion 2A together reduce the capacity of the chamber 30 as the selected timing. While the first cam portion 1A and the second cam portion 2A together reduce the volume of the chamber 30, compression of the gas present in this chamber 30 occurs.

When the first rotor 1 and the second rotor 2 continue to rotate in the opposite direction, after compression in the chamber 30, the upstream end of this chamber 30 is interrupted by the intersection of the spiral 21 and the spiral 23. When the upstream end of the chamber is blocked, the chamber 30 is shown in figure 8. The upstream end of the chamber 30 is blocked at P2 in this figure 8.

Once the blockage occurs at P2, continued rotation of the first and second rotors 1, 2 in opposite directions causes the chamber 30 to be displaced downstream in the axial direction without changing capacity. In other words, there is no compression in the cavity 30 after the blockage occurs at P2.

When the chamber 30 reaches the downstream end of the first screw 1B and the second screw 2B, there is still no compression in this chamber 30 because the outlet 16 is at a distance from the first screw 1B and the second screw 2B.

Curve C in fig. 9 is a graphical representation of the volume V of the chamber 30 as a function of time t.

From the foregoing, it can be seen that the effect of the first screw 1B and the second screw 2B does not bring about a reduction in capacity and, thus, compression. The effect of the first and second screws is to make a series of identical interruptions at the interruption point at P1, which causes the gas to be retained as it is compressed by the first and second cam portions 1A and 2A in the chamber 30. The first and second screws also have the effect of making a series of identical interruptions at the interruption point at P2, which allows the gas present in the chambers 30 of the first and second cam portions 1A and 2A to be isolated after compression.

Since compression occurs substantially at the first cam portion 1A and the second cam portion 2A, heating due to such compression also occurs substantially at the first cam portion 1A and the second cam portion 2A. With the benefit of this, a low temperature rise of the first and second screws 1B, 2B can be obtained, enabling an efficient cooling of the inner volume 14 at the first and second cam portions 1A, 2A. Further, with respect to the following: since such a screw has a complicated shape, it is considerably complicated to grasp the result of expansion of the screw, and therefore, the low temperature rise of the first screw 1B and the second screw 2B is advantageous.