TWM630997U - Improved structure of dry vacuum pump - Google Patents

Abstract

The present invention provides a structural improvement of a dry vacuum pump, comprising: a first helical rotor having a first pivot shaft, a first front tooth blade, a second front tooth blade and a first rear tooth and the first front tooth blade spirally extends along the first pivot shaft with a first front helical tooth portion and a first front tooth slot, and the second front tooth blade spirally extends along the first pivot shaft with a first front tooth portion. Two front helical tooth portions and a second front tooth slot, the first front helical tooth portion and the second front helical tooth portion helically extend on the first pivot shaft spaced apart from each other, and the first front tooth slot and the first The two front tooth slots spirally extend on the first pivot shaft spaced apart from each other; and a second helical rotor has a second pivot shaft and a third front tooth blade and a fourth front tooth blade and a The second rear tooth blade, and the third front tooth blade spirally extends along the second pivot axis with a third front helical tooth portion and a third front tooth slot, and the fourth front tooth blade along the second pivot axis A fourth front helical tooth portion and a fourth front tooth slot are spirally extended, the third front helical tooth portion and the fourth front helical tooth portion are helically extended on the second pivot shaft at a distance from each other, and the third front helical tooth portion and the third front tooth The slot and the fourth front tooth slot are spaced apart from each other and extend on the second pivot shaft. Therefore, through the configuration design of the double front blade helix and the single rear blade, the dynamic balance can be improved, the rotation speed can be increased, the processing gas volume can be increased, It is convenient for processing and forming and improves the efficiency of mass production.

Description

Structure Improvement of Dry Vacuum Pump

This work is about a dry vacuum pump, especially a dry vacuum pump structure improvement that can improve dynamic balance, increase speed, increase processing gas volume, facilitate processing and forming, and improve mass production efficiency.

The use of vacuum pumps is mainly to inhale and discharge gas to form a pump that connects the cavity to generate negative pressure. There are many types of vacuum pumps, such as positive displacement dry vacuum pumps, which are mainly two-shaft type screw pumps. The shell has A suction port and a discharge port, and the housing transfers the gas from the suction port to the discharge port through a pair of rotors synchronously and reversely rotated. At present, dry vacuum pumps on the market are mainly divided into single-blade screw rotors and double-blade screw rotors. The single-blade helical rotor is inherently the geometric configuration of the mass eccentric, so on the section perpendicular to the rotating shaft, its centroid does not coincide with the rotating shaft, so it is prone to overall unbalance and abnormal vibration of the machine body. In order to solve the problem of balance, the conventional method used by the industry is to remove the material on the rotor blades through the dynamic balancing machine to reduce the weight. Although this method can improve the dynamic balance, the vacuum pump will also be airtight due to its holes. The effect becomes worse, and extra man-hours and construction costs are also added to the manufacturing. On the contrary, the rotor with the whole section of the airfoil is a double-blade helix, although it can effectively achieve a good level of rotational dynamic balance, but the design of the full-section double-blade helical rotor is easy. As a result, the aspect ratio of the helical tooth profile in the exhaust section will be too high, which will limit the shank diameter of the machining tool for the tooth profile, thereby causing processing difficulties.

Therefore, how to solve the above-mentioned problems and deficiencies of conventional use is the direction that the creators of this creation and related manufacturers in this industry are eager to research and improve.

Therefore, in order to effectively solve the above problems, the main purpose of this creation is to provide a dry vacuum pump structure improvement that can improve dynamic balance, increase rotational speed, increase processing gas volume, facilitate processing and forming, and improve mass production efficiency.

In order to achieve the above purpose, the present invention provides a structural improvement of a dry vacuum pump, which includes: a first helical rotor, the first helical rotor has a first pivot shaft, a first front tooth blade, a second front tooth blade, and a first rear toothed blade, the first pivot has a first intake front end and a first air outlet rear end, and the first front toothed blade and the second front toothed blade are arranged on the first air intake At the front end, the first front tooth blade spirally extends along the first pivot shaft with a first front helical tooth portion and a first front tooth slot, and the second front tooth blade spirals along the first pivot shaft A second front screw tooth portion and a second front tooth slot are extended, and the first front screw tooth portion and the second front screw tooth portion are helically extended on the first pivot shaft at a distance from each other, and the first front tooth portion The slot and the second front tooth slot are spaced apart from each other and extend helically on the first pivot shaft, and the first rear tooth blade is arranged at the rear end position of the first air outlet, and the first rear tooth blade is along the first A pivot shaft spirally extends a first rear helical tooth portion, and a first rear tooth slot is formed between the first rear helical tooth portions; and a second helical rotor, the second helical rotor has a second pivot shaft and a first Three front lobes, a fourth front lobe and a second rear lobe, the second pivot has a second intake front end and a second air outlet rear end, and the third front lobe and the fourth The front toothed blade is arranged at the front end position of the second intake air, and the third front toothed blade spirally extends along the second pivot shaft with a third front screw tooth portion and a third front tooth slot, and the first A fourth front helical tooth portion and a fourth front tooth slot are spirally extended along the second pivot shaft by the four front toothed lobes, and the third front helical tooth portion and the fourth front helical tooth portion are helically extended on the On the second pivot shaft, the third front tooth slot and the fourth front tooth slot are helically extended on the second pivot shaft spaced apart from each other, and the first front helical tooth portion is engaged with the fourth front tooth slot and the fourth front tooth slot. The first front tooth slot engages the third front thread portion, the second front thread portion engages the third front tooth slot, and the second front tooth slot engages the fourth front thread portion part, and the second rear tooth blade is arranged on the first At the rear end position of the second air outlet, and the second rear tooth blade spirally extends along the second pivot shaft with a second rear helical tooth portion, a second rear tooth slot is formed between the second rear helical tooth portion, and the first A rear helical portion engages the second rear cogging and a first rear cogging engages the second rear helical portion.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, wherein the first front screw tooth portion and the second front screw tooth portion are spaced apart from each other and spirally extend along the first pivot shaft toward the rear end of the first outlet, and the other is The third front helical tooth portion and the fourth front helical tooth portion are spaced apart from each other and spirally extend toward the second air outlet rear end along the second pivot axis.

According to one embodiment of the structural improvement of the dry vacuum pump of the present invention, the end of the first front helical tooth portion and the end of the first rear helical tooth portion are extended and connected to each other, and the end of the third front helical tooth portion is connected to Ends of the second rear screw teeth are extended and connected to each other.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, a first extension space is formed between the end of the first front thread part and the end of the first rear thread part, and the third front thread part A second extension space is formed between the end and the end of the second rear screw tooth portion.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, the outer diameter formed by the first front screw tooth portion and the second front screw tooth portion is larger than the outer diameter formed by the first rear screw tooth portion, and the third front The outer diameter formed by the helical tooth portion and the fourth front helical tooth portion is larger than the outer diameter formed by the second rear helical tooth portion.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, the outer diameter formed by the first front screw tooth portion and the second front screw tooth portion is equal to the outer diameter formed by the first rear screw tooth portion, and the third front screw tooth portion is formed with an outer diameter equal to The outer diameter formed by the helical tooth portion and the fourth front helical tooth portion is equal to the outer diameter formed by the second rear helical tooth portion.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, the width of the first front tooth slot and the second front tooth slot is greater than the width of the first rear tooth slot, and the third front tooth slot and the fourth front tooth slot The width is greater than the width of the second rear tooth slot.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, the tooth shape of the first front tooth blade and the second front tooth blade is the same, and the tooth shape of the third front tooth blade and the fourth front tooth blade is the same.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, the tooth shapes of the first front tooth blade and the second front tooth blade are different.

According to an embodiment of the structural improvement of the dry vacuum pump of the present invention, the tooth shapes of the third front tooth blade and the fourth front tooth blade are different.

1: structural improvement of dry vacuum pump

2: The first helical rotor

21: First Pivot

211: First intake front end

212: First exhaust rear end

22: First anterior tooth lobe

221: The first front screw part

222: First front cogging

23: Second anterior tooth lobe

231: The second front screw part

232: Second front cogging

24: First posterior tooth lobe

241: The first rear screw part

242: First rear cogging

25: The first extension space

3: Second helical rotor

31: Second pivot

311: Second intake front end

312: Second exhaust rear end

32: Third anterior tooth lobe

321: The third front screw

322: Third front cogging

33: Fourth anterior tooth lobe

331: Fourth front screw tooth

332: Fourth front cogging

34: Second posterior tooth lobe

341: Second rear screw teeth

342: Second rear cogging

35: Second extension space

Figure 1 is a three-dimensional schematic diagram of the structural improvement of the dry vacuum pump created.

Figure 2 is a schematic side view of the structural improvement of the dry vacuum pump created.

FIG. 3 is a schematic view of the implementation of the inventive dry vacuum pump structure improvement with an extension space between the front screw tooth portion and the rear screw tooth portion.

Figure 4 is a schematic diagram of the implementation of the different outer diameters of the front and rear screw teeth of the improved structure of the dry vacuum pump.

The above-mentioned purpose of the present invention and its structural and functional characteristics will be described with reference to the preferred embodiments of the accompanying drawings.

In the following, for the composition and technical content of the structural improvement of the dry vacuum pump in the present creation, various applicable examples are listed and described in detail with reference to the accompanying drawings; however, the present creation is of course not limited to the listed ones. Such examples, drawings or detailed descriptions are only.

Furthermore, those who are familiar with this technology should also understand that: the enumerated embodiments and the attached drawings are only for reference and description, not for limiting the creation; it can be easily implemented based on these records. The creations completed by modification or alteration are also considered to be within the scope of the spirit and intent of this creation. Of course, such creations are also included in the scope of the patent application of this creation.

In addition, the directional terms mentioned in the following embodiments, such as "up", "down", "left", "right", "front", "rear", etc., are only for referring to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate rather than limit the present invention; furthermore, in the following embodiments, the same or similar elements will use the same or similar reference numerals.

Please refer to Figures 1 and 2, which are a three-dimensional schematic view and a schematic side view of the structural improvement of the dry vacuum pump of the present creation. It can be clearly seen from the figures that the structural improvement 1 of the dry vacuum pump mainly includes a first A helical rotor 2 and a second helical rotor 3, wherein the first helical rotor 2 and the second helical rotor 3 are arranged in a casing with a cavity, and the cavity defines an air inlet side and an air outlet side.

The first helical rotor 2 mainly has a first pivot shaft 21 . The end of the first pivot shaft 21 at the intake side is formed with a first intake front end 211 , and the end at the outlet side is formed with a first intake front end 211 . There is a first air outlet rear end 212, and the first helical rotor 2 further has a first front toothed blade 22 and a second front toothed blade 23, and the first front toothed blade 22 is disposed at the first intake air A first front tooth portion 221 and a first front tooth slot 222 are spirally extended from the first front tooth blade 22 along the first pivot shaft 21 at one side of the front end 211 , and the second front tooth blade 23 It is disposed at the position on the other side of the first intake front end 211 relative to the first front toothed blade 22 , and the second front toothed blade 23 spirally extends along the first pivot 21 with a second front screw tooth portion. 231 and a second front tooth slot 232, and the first front screw tooth portion 221 and the second front screw tooth portion 231 are spaced apart from each other and extend spirally along the first pivot shaft 21 toward the first air outlet rear end 212, In addition, the first rear tooth blade 24 is disposed on the At the position of the first air outlet rear end 212, and the first rear toothed blade 24 spirally extends along the first pivot shaft 21 toward the first air intake front end 211, a first rear helical tooth portion 241 is spirally extended. A first rear tooth slot 242 is formed between the screw teeth 241 .

The second helical rotor 3 mainly has a second pivot shaft 31 , and a second intake front end 311 is formed at the end of the second pivot shaft 31 at the position of the intake side, and formed at the end of the second pivot shaft at the position of the outlet side. There is a second air outlet rear end 312, and the second helical rotor 3 further has a third front toothed blade 32 and a fourth front toothed blade 33, and the third front toothed blade 32 is disposed at the second intake air A third front tooth portion 321 and a third front tooth slot 322 are spirally extended from the third front tooth blade 32 along the second pivot shaft 31 at one side of the front end 311 , and the fourth front tooth blade 33 It is disposed at the position on the other side of the second intake front end 311 relative to the third front toothed blade 32 , and the fourth front toothed blade 33 spirally extends along the second pivot 31 with a fourth front helical tooth portion. 331 and a fourth front tooth slot 332, and the third front screw tooth portion 321 and the fourth front screw tooth portion 331 are spaced apart from each other and spirally extend along the second pivot shaft 31 toward the second air outlet rear end 312, In addition, the second rear toothed blade 34 is disposed at the position of the second air outlet rear end 312 , and the second rear toothed blade 34 spirally extends along the second pivot shaft 31 toward the second air intake front end 311 with a first Two rear screw teeth 341 , and a second rear tooth slot 342 is formed between the second rear screw teeth 341 .

Furthermore, the tooth shape of the first front toothed blade 22 and the second front toothed blade 23 can be designed according to the compression requirements, and the first front toothed blade 22 and the second front toothed blade 23 can have the same tooth shape or the tooth shape. The shapes are different, and the number of helical turns of the first front helical tooth portion 221 of the first front toothed blade 22 and the second front helical tooth portion 231 of the second front toothed blade 23 can be 1 to 2 turns, and the first rear toothed The number of helical turns of the first rear helical tooth portion 241 of the blade 24 may be 2-6 turns. In this embodiment, the tooth shape of the first front tooth blade 22 and the second front tooth blade 23 are the same, and the The number of turns of a front screw tooth portion 221 is 2 turns, the number of turns of the second front screw tooth portion 231 is 1 turn, the number of turns of the first rear tooth blade 24 is 4 turns, and the number of turns of the first front screw tooth portion 221 The end of the first rear screw tooth portion 241 is extended and connected to each other, and vice versa, If the number of turns of the second front threaded portion 231 is 2, the end of the second front threaded portion 231 and the end of the first rear threaded portion 241 are extended and connected to each other. In this embodiment, The outer diameter formed by the first front thread portion 221 and the second front thread portion 231 is equal to the outer diameter formed by the first rear thread portion 241 , and the first front tooth slot 222 and the second front tooth slot 232 The width is greater than the width of the first rear tooth slot 242 .

Furthermore, the tooth shape of the third front toothed blade 32 and the fourth front toothed blade 33 can also be designed according to the compression requirements, and the third front toothed blade 32 and the fourth front toothed blade 33 can have the same tooth shape or The tooth types are different, and the number of helical turns of the third front helical tooth portion 321 of the third front toothed blade 32 and the fourth front helical tooth portion 331 of the fourth front toothed blade 33 can be 1 to 2 turns, and the second rear The number of helical turns of the second rear helical tooth portion 341 of the toothed blade 34 may be 2˜6. In this embodiment, the tooth shape of the third front toothed blade 32 and the fourth front toothed blade 33 are the same, and the The number of turns of the third front threaded portion 321 is 2 turns, the number of turns of the fourth front threaded portion 331 is 1 turn, and the number of turns of the second rear tooth blade 34 is 4 turns, and the third front threaded portion 331 has 4 turns. The end of the 321 is extended and connected to the end of the second rear thread portion 341. On the contrary, if the number of turns of the fourth front thread portion 331 is 2, the end of the fourth front thread portion 331 and the end of the thread portion 331 are connected to each other. Ends of the second rear screw teeth 341 are extended and connected to each other. In this embodiment, the outer diameters formed by the third front screw teeth 321 and the fourth front screw teeth 331 are equal to the second rear screw teeth 341 . The formed outer diameter and the width of the third front tooth slot 322 and the fourth front tooth slot 332 are larger than the width of the second rear tooth slot 342 .

The first front thread portion 221 engages with the fourth front thread slot 332, the first front thread portion 222 engages with the third front thread portion 321, and the second front thread portion 231 is engaged with the third front thread portion 321. The third front tooth slot 322 and the second front tooth slot 232 are engaged with the fourth front screw tooth portion 331 , and the first rear screw tooth portion 241 is engaged with the second rear tooth slot 342 and the first screw tooth portion 331 . A rear tooth slot 242 is engaged with the second rear screw tooth portion 341 , and although the screw tooth portion and the tooth slot are engaged with each other, a small relative gap is maintained therebetween, and the extension design is made in the form of non-contact.

When the first helical rotor 2 and the second helical rotor 3 through their high-speed rotation, the gas is inhaled by the sealed inter-tooth volume of the rotor, and the strokes of suction, gas transmission and exhaust are started, and the main is through The first front tooth 22 and the second front tooth 23 of the first helical rotor 2 extend to the first rear tooth 24 , and the third front tooth 32 and the fourth front tooth 33 of the second helical rotor 3 extend The multi-stage lead rotor design to the second rear tooth blade 34 makes the first helical rotor 2 and the second helical rotor 3 easy to process and form, and the width of the first front tooth slot 222 and the second front tooth slot 232 is larger than The width of the first rear cogging 242 and the widths of the third front cogging 322 and the fourth front cogging 332 are larger than the width of the second rear cogging 342 to provide an operation mode with a large compression ratio and power saving, thereby achieving improved dynamic performance. Balance, can increase the speed, increase the processing gas volume, facilitate processing and forming, and improve the efficiency of mass production.

Please refer to the aforesaid drawings and FIG. 3 , which are schematic diagrams of the implementation of the improved dry vacuum pump structure with an extension space between the front screw teeth and the rear screw teeth, wherein the first front tooth blade 22 is the first The number of helical turns of the front helical tooth portion 221 and the second front helical tooth portion 231 of the second front toothed blade 23 can be 1 to 2 turns, and the number of helical turns of the first rear helical tooth portion 241 of the first rear toothed blade 24 The number of turns may be 2 to 6 turns, and in this embodiment, the number of turns of the first front screw tooth portion 221 is 2 turns, the number of turns of the second front screw tooth portion 231 is 2 turns, and the first rear tooth blade 24 The number of turns is 3, and the end of the second front threaded portion 231 and the end of the first rear threaded portion 241 are not extended and connected to each other and a first extension space 25 is formed therebetween, and the third front The number of turns of the threaded portion 321 is 2, the number of turns of the fourth front threaded portion 331 is 2, and the number of turns of the first rear tooth blade 24 is 3, and the end of the fourth front threaded portion 331 It is not connected to the end of the second rear helical tooth portion 341 and forms a second extension space 35 therebetween. In this embodiment, it mainly describes the first helical rotor 2 and the second helical rotor. The lead design among the 3 can have different number of turns design and different extension methods, which also do not extend to the first rear tooth blade through the first front tooth blade 22 and the second front tooth blade 23 of the first helical rotor 2 24. The third front toothed blade 32 and the fourth front toothed blade 33 of the second helical rotor 3 do not extend to the second rear toothed blade 34 The multi-stage lead rotor design makes the first helical rotor 2 and the second helical rotor 3 easy to process and form, and the width of the first front tooth slot 222 and the second front tooth slot 232 is larger than the width of the first rear tooth slot 242. The width and the width of the third front cogging 322 and the fourth front cogging 332 are greater than the width of the second rear cogging 342 to provide a large compression ratio and power saving operation mode, thereby achieving improved dynamic balance, increased rotational speed, and increased power consumption. It can handle gas volume, facilitate processing and forming, and improve the efficiency of mass production.

Please refer to FIG. 4 again, which is a schematic view of the implementation of the structure improvement of the dry vacuum pump of the present invention with different outer diameters of the front helical part and the rear helical part, except for the first front helical part 221 and the second front helical part 231 The formed outer diameter is equal to the outer diameter formed by the first rear screw tooth portion 241 , and the outer diameter formed by the third front screw tooth portion 321 and the fourth front screw tooth portion 331 is equal to the outer diameter formed by the second rear screw tooth portion 341 . In this embodiment, the outer diameter formed by the first front thread portion 221 and the second front thread portion 231 may also be larger than the outer diameter formed by the first rear thread portion 241, and the The outer diameter formed by the third front helical part 321 and the fourth front helical part 331 can also be larger than the outer diameter formed by the second rear helical part 341 . Under the changing conditions, it can also achieve the effects of improving dynamic balance, increasing rotational speed, increasing processing gas volume, facilitating processing and forming, and improving mass production efficiency.

This creation has been described in detail above, but the above is only a preferred embodiment of this creation, and should not limit the scope of this creation, that is, all equal changes and modifications made according to the scope of this creation application etc., shall still be covered by the patent of this creation.

1: structural improvement of dry vacuum pump

2: The first helical rotor

21: First Pivot

211: First intake front end

212: First exhaust rear end

22: First anterior tooth lobe

221: The first front screw part

222: First front cogging

23: Second anterior tooth lobe

231: The second front screw part

232: Second front cogging

24: First posterior tooth lobe

241: The first rear screw part

242: First rear cogging

3: Second helical rotor

31: Second pivot

311: Second intake front end

312: Second exhaust rear end

32: Third anterior tooth lobe

321: The third front screw

322: Third front cogging

33: Fourth anterior tooth lobe

331: Fourth front screw tooth

332: Fourth front cogging

341: Second rear screw teeth

342: Second rear cogging

Claims (10)

A structural improvement of a dry vacuum pump, comprising: a first helical rotor, the first helical rotor having a first pivot, a first front tooth blade, a second front tooth blade and a first rear tooth blade, the first A pivot has a first air intake front end and a first air outlet rear end, and the first front toothed blade and the second front toothed blade are arranged at the first air intake front end position, and the first front toothed blade is The tooth blade spirally extends along the first pivot shaft with a first front helical tooth portion and a first front tooth slot, and the second front tooth blade spirally extends along the first pivot shaft with a second front helical tooth portion and A second front tooth slot, and the first front screw tooth portion and the second front screw tooth portion spirally extend on the first pivot shaft at a distance from each other, and the first front tooth slot and the second front tooth slot are mutually The interval spiral extends on the first pivot shaft, and the first rear tooth blade is arranged at the position of the first air outlet rear end, and the first rear tooth blade spirally extends along the first pivot shaft with a first rear tooth blade. a helical tooth part, a first rear tooth slot is formed between the first rear helical tooth part; and a second helical rotor, the second helical rotor has a second pivot, a third front tooth blade and a fourth front The toothed blade and a second rear toothed blade, the second pivot has a second intake front end and a second air outlet rear end, and the third front toothed blade and the fourth front toothed blade are arranged on the first At the front end position of the two intake air, and the third front toothed blade spirally extends along the second pivot shaft with a third front helical tooth portion and a third front tooth slot, and the fourth front toothed blade is along the second A fourth front helical tooth portion and a fourth front tooth slot are spirally extended on the pivot shaft, and the third front helical tooth portion and the fourth front helical tooth portion are helically extended on the second pivot shaft at a distance from each other. The three front tooth grooves and the fourth front tooth groove are helically extended on the second pivot shaft at a distance from each other, and the first front helical tooth portion engages the fourth front tooth groove and the first front tooth groove. The third front helical tooth portion, and the second front helical tooth portion engages the third front tooth slot and the second front tooth slot engages the fourth front helical tooth portion, and the second rear tooth blade is arranged at the rear end of the second air outlet, and the first The two rear tooth blades spirally extend along the second pivot shaft with a second rear helical tooth portion, a second rear tooth slot is formed between the second rear helical tooth portions, and the first rear helical tooth portion engages the first rear helical tooth portion. The second rear splines engage the second rear helical teeth with the first rear cogging. The structural improvement of the dry vacuum pump according to claim 1, wherein the first front helical tooth portion and the second front helical tooth portion are spaced apart from each other and spirally extend along the first pivot shaft toward the rear end of the first gas outlet, and the other is The third front helical tooth portion and the fourth front helical tooth portion are spaced apart from each other and spirally extend toward the second air outlet rear end along the second pivot axis. The structural improvement of the dry vacuum pump as claimed in claim 2, wherein the end of the first front helical tooth portion and the end of the first rear helical tooth portion are extended and connected to each other, and the end of the third front helical tooth portion is connected to Ends of the second rear screw teeth are extended and connected to each other. The structural improvement of the dry vacuum pump as claimed in claim 2, wherein a first extension space is formed between the end of the first front thread portion and the end of the first rear thread portion, and the third front thread portion A second extension space is formed between the end and the end of the second rear screw tooth portion. The structural improvement of the dry vacuum pump according to claim 1, wherein the outer diameter formed by the first front helical part and the second front helical part is larger than the outer diameter formed by the first rear helical part, and the third front The outer diameter formed by the helical tooth portion and the fourth front helical tooth portion is larger than the outer diameter formed by the second rear helical tooth portion. The structural improvement of the dry vacuum pump according to claim 1, wherein the outer diameter formed by the first front helical tooth portion and the second front helical tooth portion is equal to the outer diameter formed by the first rear helical tooth portion, which is the same as the third front helical tooth portion. The outer diameter formed by the helical tooth portion and the fourth front helical tooth portion is equal to the outer diameter formed by the second rear helical tooth portion. The structural improvement of the dry vacuum pump as claimed in claim 1, wherein the widths of the first front cogging and the second front cogging are greater than the width of the first rear cogging, and the third front cogging and the fourth front cogging The width is greater than the width of the second rear tooth slot. The structural improvement of the dry vacuum pump as claimed in claim 1, wherein the tooth shape of the first front tooth blade and the second front tooth blade is the same, and the tooth shape of the third front tooth blade and the fourth front tooth blade is the same. The structural improvement of the dry vacuum pump as claimed in claim 1, wherein the tooth shapes of the first front tooth blade and the second front tooth blade are different. The structural improvement of the dry vacuum pump as claimed in claim 1, wherein the tooth shapes of the third front tooth blade and the fourth front tooth blade are different.

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