Multi-stage variable-pitch screw vacuum pump with adjustable compression ratio

Abstract

The utility model provides a multistage variable-pitch screw vacuum pump with an adjustable compression ratio, taking two stages as an example, two parallel first-stage screws with equal pitch are arranged in a first-stage pump cavity, two parallel second-stage screws with equal pitch are arranged in a second-stage pump cavity, the pitch of the first-stage screws is larger than that of the second-stage screws, and the pitch of the second-stage screws is larger than that of the first-stage screws. A synchronous gear is installed on a shaft at one end of each first-stage screw rod and a shaft at one end of each second-stage screw rod, a variable gear is installed on a shaft at the other end of one first-stage screw rod, and the variable gear is located on the outer side of a bearing at the end. And a shaft at the other end of the second-stage screw positioned under the first-stage screw is also provided with a change gear. Through the adjustment of the change gear and the change of the screw pitch values of the upper and lower layers, the air suction and exhaust device is convenient to machine and install, the air suction and exhaust capacity is greatly improved, the working efficiency is high, the adjustment method is flexible, and the complex and changeable working conditions can be effectively coped with.

Description

Technical Field

[0001] The utility model belongs to the technical field of vacuum pump manufacturing, and in particular relates to a multi-stage variable pitch screw vacuum pump with adjustable compression ratio. Background Art

[0002] The utility model patent with the authorization announcement number CN 219529309 U discloses a two-stage series screw vacuum pump, which sets two sets of screws (two upper screws and two lower screws) in series along the flow direction of the airflow in the pump chamber, thereby forming a screw vacuum pump structure with two levels. Compared with a single-stage screw vacuum pump with the same power, the utility model improves the suction and exhaust capabilities. However, the utility model also has some obvious defects in the structural design, which are mainly manifested in the following two aspects:

[0003] First, from the attached drawings, the utility model uses rotors (impellers) of the same diameter and length in the upper and lower layers. There is no volume difference between the two sets of rotors in the upper and lower layers, and no compression ratio is formed, making it difficult to achieve a graded compression effect.

[0004] Second, the transmission of the upper and lower layers of the utility model is completed by belts, which have low transmission efficiency and poor reliability. In addition, the belt transmission requires the pre-tightening force of the belt to be tightened. This pre-tightening force acts on the main shaft all the time, which is easy to cause the operation failure of the main shaft, bearings or shaft seal components. In addition, if three belts are used, the transmission cannot be carried out, and the power cannot be directly transmitted to the third layer of rotor through the third gear like gears. Therefore, the utility model can only realize two-stage series connection, and cannot realize multi-stage series connection.

[0005] It should also be noted that utility model patent No. CN 219529309 U does not involve the field of variable pitch at all, and other existing technologies involving variable pitch (existing variable pitch screw vacuum pumps) are all achieved by changing the pitch of the screw on the same set of rotors, and the technical concept of layered variable pitch has never appeared.

[0006] In summary, due to the above-mentioned structural design defects, it is difficult for the utility model to effectively improve the vacuum degree of the screw vacuum pump and is difficult to apply to complex and changeable working conditions. Summary of the invention

[0007] The utility model aims to overcome the technical defects of the above-mentioned prior art that the transmission structure design of the upper and lower layers is unreasonable, the compression ratio between the layers cannot be adjusted, and thus it is difficult to apply to complex and changeable working conditions.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] A multi-stage variable pitch screw vacuum pump with adjustable compression ratio comprises an air inlet and an exhaust port, wherein the air inlet is communicated with a first-stage pump chamber, the first-stage pump chamber is communicated with a second-stage pump chamber below it, and the second-stage pump chamber is communicated with the exhaust port; two parallel first-stage screws with equal pitch are arranged in the first-stage pump chamber, and two parallel second-stage screws with equal pitch are arranged in the second-stage pump chamber, wherein the pitch of the first-stage screw is greater than the pitch of the second-stage screw; bearings and shaft sealing components are arranged on the shafts at both ends of each first-stage screw and each second-stage screw, a synchronous gear is installed on the shaft at one end of each first-stage screw and each second-stage screw, and the synchronous gear is located on the outside of the bearing at this end; a speed change gear is installed on the shaft at the other end of one of the first-stage screws, and the speed change gear is located on the outside of the bearing at this end, and correspondingly, a speed change gear is also installed on the shaft at the other end of a second-stage screw located directly below the first-stage screw, and the speed change gear is located on the outside of the bearing at this end.

[0010] On the basis of the above technical solutions, the present invention may be supplemented with the following technical means so as to better or more specifically solve the technical problems to be solved by the present invention.

[0011] An oil tank is respectively arranged beside each of the speed change gears and the synchronous gears.

[0012] Furthermore, a third-stage pump chamber is provided below the second-stage pump chamber, the second-stage pump chamber is communicated with the third-stage pump chamber below it, the third-stage pump chamber is communicated with the exhaust port below it, two parallel third-stage screws with equal pitches are arranged in the third-stage pump chamber, synchronous gears are installed on the shafts at the same end of the two third-stage screws, one of which is located directly below the second-stage screw on which the speed change gear is installed, and a speed change gear is installed on the shaft at the other end of the third-stage screw, through the mutual engagement of the upper and lower speed change gears, the third-stage screw can rotate in the opposite direction to the second-stage screw, and drive the other third-stage screw to rotate synchronously in the opposite direction relative to it through the synchronous gear at its other end.

[0013] Furthermore, a fourth-stage pump chamber is provided below the third-stage pump chamber, the third-stage pump chamber is communicated with the fourth-stage pump chamber below it, the fourth-stage pump chamber is communicated with the exhaust port below it, two parallel fourth-stage screws with equal pitches are arranged in the fourth-stage pump chamber, synchronous gears are installed on the shafts at the same end of the two fourth-stage screws, one of which is located directly below the third-stage screw on which the speed gear is installed, and a speed gear is installed on the shaft at the other end of the fourth-stage screw, through the mutual engagement of the upper and lower speed gears, the fourth-stage screw can rotate in the opposite direction to the third-stage screw, and drive the other fourth-stage screw to rotate synchronously in the opposite direction with it through the synchronous gear at its other end.

[0014] Compared with the prior art, the main beneficial effects of the utility model are as follows:

[0015] The compression ratio between each level of the utility model can be adjusted by adjusting the speed ratio of the speed gear. In addition, the utility model adopts a structural design in which the screw pitches in the same level are equal and the screw pitches in different levels are different. This structural design can further improve the vacuum degree of the screw pump. In particular, compared with the existing variable pitch screw pump technology, the utility model adopts a layered variable pitch scheme in which each layer has an equal pitch. The difficulty of processing and installing the screw is greatly reduced, and the rotor is not prone to stuck failure. In addition, the impurity components in the gas are easier to discharge out of the pump, and the reliability of equipment operation is greatly improved. In short, the utility model is not only easy to process and install, but also greatly improves the ability of the screw vacuum pump to evacuate and exhaust air. It has high working efficiency and flexible adjustment methods, and can effectively cope with complex and changeable working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a vertical section structure schematic diagram of an embodiment of the utility model;

[0017] Figure 2 yes Figure 1 Schematic diagram of the AA horizontal section structure in;

[0018] Figure 3 yes Figure 2 A partial enlarged view of .

[0019] In the figure:

[0020] 1——first stage screw; 2——second stage screw;

[0021] 3 – air inlet; 4 – exhaust outlet;

[0022] 501——first stage speed gear; 502——second stage speed gear;

[0023] 601——first stage synchronous gear; 602——second stage synchronous gear;

[0024] 7——shaft seal components; 8——bearings;

[0025] 9——Fuel tank. DETAILED DESCRIPTION

[0026] In order to facilitate those skilled in the art to more fully understand the technical solution and working principle of the present utility model, an embodiment of the present utility model is described below in conjunction with the accompanying drawings.

[0027] like Figures 1 to 3As shown, a multi-stage variable pitch screw vacuum pump with adjustable compression ratio includes an air inlet 3 and an exhaust port 4, the air inlet 1 is connected to the first-stage pump chamber, the first-stage pump chamber is connected to the second-stage pump chamber below it, and the second-stage pump chamber is connected to the exhaust port 4; two parallel first-stage screws 1 with equal pitches are arranged in the first-stage pump chamber, and two parallel second-stage screws 2 with equal pitches are arranged in the second-stage pump chamber, the pitch of the first-stage screw 1 is greater than the pitch of the second-stage screw 2, specifically, the screw pitch of the first-stage screw is 1.2 to 4 times the screw pitch of the second-stage screw; bearings 8 and shaft sealing components 7 are arranged on the shafts at both ends of each first-stage screw 1 and each second-stage screw 2, and a first-stage synchronous gear 6 is installed on the shaft at one end (the left end in the figure) of each first-stage screw 1 01, a second-stage synchronous gear 602 is installed on the shaft of one end (the left end in the figure) of each second-stage screw rod 2, and the first-stage synchronous gear 601 and the second-stage synchronous gear 602 are located on the outside of the bearing 8 of the corresponding end; a speed change gear 501 is installed on the shaft of the other end (the right end in the figure) of one of the first-stage screw rods 1, and the speed change gear 501 is located on the outside of the bearing 8 of this end. Correspondingly, a second-stage speed change gear 502 is installed on the shaft of the other end (the right end in the figure) of a second-stage screw rod 2 located directly below the first-stage screw rod 1, and the second-stage speed change gear 502 is located on the outside of the bearing 8 of this end. Oil tanks 9 are respectively arranged next to the first-stage speed change gear 501, the second-stage speed change gear 502, the first-stage synchronous gear 601, and the second-stage synchronous gear 602.

[0028] Among the two first-stage screws 1, one first-stage screw 1 equipped with a first-stage speed gear 501 is driven by a motor matched with the present invention, and correspondingly, one second-stage screw 2 equipped with a second-stage speed gear 502 is located directly below the first-stage screw 1, and the first-stage speed gear 501 and the second-stage speed gear 502 are in contact with each other. When the motor drives a first-stage screw rotor (the first-stage screw rotor is composed of the first-stage screw 1 and an impeller installed on the shaft of the first-stage screw 1) to rotate, the synchronous gears 6 installed on the shafts of the two first-stage screws 1 mesh with each other, thereby driving the other first-stage screw rotor to rotate synchronously in the opposite direction. At the same time, the second-stage screw rotor (the second-stage screw rotor consists of a second-stage screw 2 and an impeller installed on the shaft of the second-stage screw 2) is driven to rotate in the opposite direction through the mutual engagement of the upper and lower speed gears (i.e., the first-stage speed gear 501 and the second-stage speed gear 502), and the driven second-stage screw rotor is driven to rotate in the opposite direction synchronously with the other second-stage screw rotor through the mutual engagement of the synchronous gears 602 installed at the other ends of the two second-stage screws 2.

[0029] In this embodiment, different layers of screw rotors are designed with different diameters and pitches, but each layer of rotors itself has equal pitches, and the air pumping rate of the upper screw rotor (upper layer of screw rotor) is 1.5 to 3 times the air pumping rate of the lower screw rotor (lower layer of screw rotor), which can achieve multi-stage layered compression, thereby forming an overall layered variable pitch screw vacuum pump. The rotation speed ratio of the first-stage speed change gear 501 and the second-stage speed change gear 502 can be adjusted and replaced according to the needs of the working conditions, so that the compression ratio between layers can be further adjusted by changing the speed.

[0030] The structural features and working principle of an embodiment of the utility model are described above in conjunction with the accompanying drawings. It should be particularly noted that in the actual implementation of the utility model, the level of the screw vacuum pump can be increased according to actual needs.

[0031] For example, a third-stage pump chamber is also provided below the second-stage pump chamber, the second-stage pump chamber is connected to the third-stage pump chamber below it, the third-stage pump chamber is connected to the exhaust port below it, two parallel third-stage screws with equal pitches are arranged in the third-stage pump chamber (the third-stage screw and its impeller constitute the third-stage screw rotor), and third-stage synchronous gears are installed on the shafts at the same end of the two third-stage screws, wherein a third-stage speed gear is installed on the shaft of the other end (corresponding to the right end in the figure) of a third-stage screw located directly below the second-stage screw on which the second-stage speed gear 502 is installed, and through the mutual engagement of the upper and lower speed gears (i.e., the second-stage speed gear 502 and the third-stage speed gear), the third-stage screw can rotate in the opposite direction relative to the second-stage screw, and drive the other third-stage screw to rotate synchronously in the opposite direction relative to it through the third-stage synchronous gear at its other end.

[0032] For another example, a fourth-stage pump chamber can be arranged below the third-stage pump chamber, the third-stage pump chamber is connected to the fourth-stage pump chamber below it, the fourth-stage pump chamber is connected to the exhaust port below it, two parallel fourth-stage screws with equal pitch are arranged in the fourth-stage pump chamber (the fourth-stage screw and its rotor constitute the fourth-stage screw rotor), and fourth-stage synchronous gears are installed on the shafts at the same end of the two fourth-stage screws, wherein the fourth-stage speed gear is installed on the shaft of the other end (corresponding to the right end in the figure) of the fourth-stage screw directly below the third-stage screw on which the third-stage speed gear is installed, and the fourth-stage screw can rotate in the opposite direction relative to the third-stage screw through the mutual engagement of the upper and lower speed gears (i.e., the third-stage speed gear and the fourth-stage speed gear), and drive the other fourth-stage screw to rotate synchronously in the opposite direction relative to it through the fourth-stage synchronous gear at its other end.

[0033] When the utility model adopts a four-stage structure from top to bottom, the screw pitch of the first-stage screw is 1.2 to 4 times the screw pitch of the second-stage screw, the screw pitch of the second-stage screw is 1.2 to 4 times the screw pitch of the third-stage screw, and the screw pitch of the third-stage screw is 1.2 to 4 times the screw pitch of the fourth-stage screw.

[0034] In the process of implementing the utility model, the sizes of the speed gears of different layers can be replaced according to the needs of actual working conditions, and different gear ratios can achieve different speed ratios, so that the speed of each stage of the screw can be adjusted according to the needs of the working conditions, and the compression ratio between layers can also change accordingly after the speed is adjusted.

[0035] In short, due to the adoption of the above-mentioned technical means, the utility model is not only easy to process and install, but also greatly improves the suction and exhaust capabilities of the screw vacuum pump. It has high working efficiency and flexible adjustment methods, and can effectively cope with complex and changeable working conditions.

Claims

1. A multi-stage variable pitch screw vacuum pump with adjustable compression ratio, comprising an air inlet and an exhaust port, wherein the air inlet is communicated with a first-stage pump chamber, the first-stage pump chamber is communicated with a second-stage pump chamber below it, and the second-stage pump chamber is communicated with the exhaust port; two parallel first-stage screws with equal pitches are arranged in the first-stage pump chamber, and two parallel second-stage screws with equal pitches are arranged in the second-stage pump chamber, bearings and shaft sealing components are arranged on the shafts at both ends of each first-stage screw and each second-stage screw, and a synchronous gear is installed on the shaft at one end of each first-stage screw and each second-stage screw, and the synchronous gear is located outside the bearing at this end; characterized in that: The pitch of the first-stage screw is greater than the pitch of the second-stage screw; a speed change gear is installed on the shaft at the other end of one of the first-stage screws, and the speed change gear is located on the outside of the bearing at this end. Correspondingly, a speed change gear is also installed on the shaft at the other end of a second-stage screw located directly below the first-stage screw, and the speed change gear is located on the outside of the bearing at this end.

2. The multi-stage variable pitch screw vacuum pump with adjustable compression ratio as claimed in claim 1, characterized in that: An oil tank is respectively arranged beside each of the speed change gears and the synchronous gears.

3. The multi-stage variable pitch screw vacuum pump with adjustable compression ratio as claimed in claim 1, characterized in that: A third-stage pump chamber is also provided below the second-stage pump chamber. The second-stage pump chamber is communicated with the third-stage pump chamber below it, and the third-stage pump chamber is communicated with the exhaust port below it. Two parallel third-stage screws with equal pitches are arranged in the third-stage pump chamber. Synchronous gears are installed on the shafts at the same end of the two third-stage screws. A speed gear is installed on the shaft at the other end of the third-stage screw, which is located directly below the second-stage screw on which the speed change gear is installed. Through the mutual engagement of the upper and lower speed change gears, the third-stage screw can rotate in the opposite direction to the second-stage screw, and drive the other third-stage screw to rotate synchronously in the opposite direction relative to it through the synchronous gear at its other end.

4. The multi-stage variable pitch screw vacuum pump with adjustable compression ratio as claimed in claim 3, characterized in that: A fourth-stage pump chamber is also provided below the third-stage pump chamber. The third-stage pump chamber is communicated with the fourth-stage pump chamber below it, and the fourth-stage pump chamber is communicated with the exhaust port below it. Two parallel fourth-stage screws with equal pitches are arranged in the fourth-stage pump chamber. Synchronous gears are installed on the shafts at the same end of the two fourth-stage screws. A speed gear is installed on the shaft at the other end of the fourth-stage screw, which is located directly below the third-stage screw on which the speed change gear is installed. Through the mutual engagement of the upper and lower speed change gears, the fourth-stage screw can rotate in the opposite direction to the third-stage screw, and drive the other fourth-stage screw to rotate synchronously in the opposite direction relative to it through the synchronous gear at its other end.

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