JPH04358787A - Screw rotor - Google Patents

Abstract

PURPOSE:To reduce leakage of gas through a clearance between rotors to increase compression performance by forming seal edges on at least either of drive side and driven side tooth faces at a position where the seal edges are not made in contact with those on the other screw rotors. CONSTITUTION:In a screw compressor in which a pair of male and female rotors 1 and 2 engaged with each other are stored rotatably in a casing 3, multiple seal edges 4 are provided on the drive side tooth faces F1 and M1 among drive side tooth faces F1 and M1 and the driven side tooth faces F2 and M2 of the male and female rotors 1 and 2, at the positions where these seal edges 4 are not made in contact with those on the mating rotors during the rotation. Thus a clearance between the male and female rotors 1 and 2, and a clearance between the rotors and the easing 3 are reduced to lesson leakage of gas through the clearances. Also, when either of the rotors 1 and 2 is made of metal and the other is of plastic, the height of the seal edge of plastic is formed slightly higher than the clearance between the rotors.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw rotor applied to a screw compressor.

0002

2. Description of the Related Art Conventionally, as shown in FIG. 6, a screw compressor has a female screw rotor (hereinafter referred to as a female rotor) 12 having a seal edge 11 formed on its teeth, a male screw rotor (hereinafter referred to as a male rotor), and a male screw rotor (hereinafter referred to as a male rotor). )13 is used,
This seal edge 11 prevents gas leakage from between the female rotor 12, male rotor 13, and the casing 14 housing them. That is, male and female rotors 12,
The smaller the gap between the male and female rotors 13 and the casing 14, the less gas leakage will occur, and it is preferable to focus on this point alone, but contact between the male and female rotors 12, 13 and the casing 14 while they are rotating can cause a major accident, and may affect machining accuracy. There is a limit to how small the gap can be made without providing the seal edge 11. On the other hand, even if the seal edge 11 comes into contact with the casing 14, it will only cause a relatively small accident, so by forming the seal edge 11 on the tip of the rotor teeth as described above, the gap can be made sufficiently small to prevent gas leakage. Efforts are being made to minimize this and improve device performance.

0003

In a screw compressor, gas leakage between the rotors has a greater effect on its performance than gas leakage between the rotor and the casing. However, since the conventional screw rotor described above only has a seal edge 11 on each tooth tip, it is effective in preventing gas leakage from the gap between the male and female rotors 12, 13 and the casing 14. However, there is a problem in that it does not help prevent gas leakage between the rotors at all. The present invention has been made to address these conventional problems, and when applied to a screw compressor, it reduces the gap between the rotors to reduce gas leakage from there.
The present invention aims to provide a screw rotor that can improve the performance of a compressor.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a seal edge on at least one of the driving side tooth surface and the non-driving side tooth surface, and the seal edge is attached to the other tooth surface of the tooth surface of the driving side and the non-driving side tooth surface. It is formed in a position that does not come into contact with the seal edge of the rotor.

[0005]

[Operation] By constructing the rotor as described above, the possibility of rotor damage due to contact between the rotors is reduced, and the gap between the rotors can be reduced.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a screw compressor to which a female rotor 1 and a male rotor 2 are applied according to a first embodiment of the present invention. be. In addition, in this embodiment, a plurality of seal edges 4 are provided on the driving side tooth surfaces F1, M1 of the driving side tooth surfaces F1, M1 and the non-driving side tooth surfaces F2, M2 of the male and female rotors 1, 2. are provided at positions that do not come into contact with the seal edges 4 of the rotors during rotation, and are formed so as to reduce the gaps between the male and female rotors 1 and 2 and between them and the casing 3.

[0007] Curves I and I indicated by broken lines in FIGS. 2 and 3
I represents the change in the clearance between the rotors at each point when the points 0 to A of the male rotor 2 shown in Fig. 1 rotate while meshing with the female rotor 1, and Fig. 2 shows the change in the gap between the rotors at each point. In the case of an oil-cooled screw compressor in which rotation is directly transmitted from the teeth to the teeth of the other rotor, Figure 3 shows the transmission from one rotor to the other rotor via gears attached to each rotor shaft, without direct contact between the rotors. This is the case with an oil-free screw compressor that transmits rotation to. In Figures 2 and 3, the solid lines III and IV indicate the gap between the male and female rotors when a screw rotor without a seal edge is used in an oil-cooled screw compressor or an oil-free screw compressor. The changes are shown for comparison.

[0008] Except for the driving point in Fig. 2, curves III and IV indicate the presence of gaps throughout, because if a seal edge is not provided, the damage caused by contact between the rotors due to the small gap is large. This is because it is necessary to provide a certain amount of clearance. On the other hand, in the case of the male and female rotors 1 and 2 provided with the sealing edge 4, the damage caused by the rotor contact is small, so the gap between the rotors is obviously small as shown in FIGS. 2 and 3. In addition, in the case of a screw rotor for an oil-cooled screw compressor, it is not necessarily necessary to provide a seal edge in the drive region where the tooth surfaces of the rotor directly contact each other and rotate the other screw rotor. do not have. The reason is that even if a sealing edge is provided in this area, the sealing edge will be worn or scraped off in a short time due to contact between the rotors.

Furthermore, if one of the male and female screw rotors 1 and 2 is made of metal and the other is made of plastic, the seal edge height of the plastic one is formed to be slightly larger than the gap between the rotors. is preferable. When a compressor incorporating a screw rotor formed in this way is operated, the seal edge with increased height initially comes into contact with the other screw rotor, creating a large resistance to rotor rotation. However, this sealing edge quickly wears out and functions to almost completely eliminate the gap between the rotors. Therefore, when the compressor is operated for a long time as shown in Fig. 4, the insulation efficiency with the seal edge shown by curve VI is higher than that without the seal edge shown by curve V. Efficiency will be 5-10% better.

As described above, in the above embodiment, a plurality of seal edges 4 are provided on the drive side tooth surfaces F1, M1 of the male and female rotors 1, 2, but the screw rotor according to the present invention does not necessarily have a drive side It is not necessary to provide only the side tooth surfaces F1, M1 or only the non-drive side tooth surfaces F2, M2.
Further, the number of seal edges 4 does not necessarily have to be plural. That is, in the present invention, the seal edge 4 is attached to the driving side tooth surface F1, M
1. It is provided on at least one of the non-drive side tooth surfaces F2 and M2, and FIG. 5 shows the second embodiment of the present invention.
An example will be shown, and as an example, the driving side tooth surface F of the female rotor 1a
1. One sealing edge 4 is provided on each of the non-drive side tooth surfaces M2 of the male rotor 2a. However, the portion L2 in FIG. 5 is a range where the seal edge 4 of the female rotor 1a may come into contact with the male rotor 2a during rotation, and the portion L1 in the figure is a range where the seal edge 4 of the male rotor 2a comes into contact with the female rotor 1a. Indicates the area that may come into contact during rotation, and both seal edges 4, 4
is formed at a position where the two never touch. Other parts in FIG. 5 that are common to those in FIG. 1 are given the same numbers and their explanations are omitted.

Furthermore, in the case of an oil-cooled screw compressor, the seal edge 4 is provided only on the non-drive side tooth surface, and in the case of an oil-free screw compressor, the seal edge 4 is provided around the entire circumference.
It is preferable to provide Furthermore, the screw rotor according to the present invention may be made of plastic and applied to a screw compressor in combination with a metal screw rotor that is not provided with a sealing edge. In addition, in the case of this plastic screw rotor, in order to form the seal edge 4,
For example, while injection molding is performed using a mold having a through hole that has the same cross-sectional shape as the screw rotor provided with the seal edge 4,
It can be formed by pulling out the molded object while twisting it. In this case, when the shrinkage rate of the plastic resin is low, the seal edge shape becomes a spiral shape, but when the shrinkage rate is high, the above-mentioned drawing is possible even if the seal edge shape is not a spiral shape. That is, the seal edge 4 in the present invention may have a helical shape, but it is not necessarily limited to this shape; it may also be provided parallel to the rotor axis, for example, and in this case also, the gap between the rotors is becomes smaller.

0012

As is clear from the above description, according to the present invention, a seal edge is attached to at least one of the drive side tooth surface and the non-drive side tooth surface, and the seal edge is attached to the other screw rotor that is in mesh with the other tooth surface. The seal edge is formed at a position that does not come into contact with the seal edge. For this reason, when applied to a screw compressor, the possibility of damage due to contact between the rotors is reduced, and the gap between the rotors can be reduced, resulting in less gas leaking from this gap. This has the effect of making it possible to improve the performance of the compressor.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a screw compressor to which a screw rotor according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram showing a change in the inter-rotor gap in an oil-cooled screw compressor when the screw rotor according to the present invention is applied and when a screw rotor without a seal edge is applied.

FIG. 3 is a diagram showing a change in the inter-rotor gap when a screw rotor according to the present invention is applied to an oil-free screw compressor and when a screw rotor without a seal edge is applied.

FIG. 4 is a diagram showing the relationship between operating time and adiabatic efficiency in a screw compressor to which a screw rotor according to the present invention is applied and a screw compressor to which a screw rotor without a seal edge is applied.

FIG. 5 is a partial sectional view of a screw compressor to which a screw rotor according to a second embodiment of the present invention is applied.

FIG. 6 is a partial cross-sectional view of a screw compressor to which a conventional screw rotor is applied.

[Explanation of symbols]

1 Female rotor 2 Male rotor 4 Seal edge M1, F1　Drive side tooth surface M2, F2　Non-drive side tooth surface

Claims (1)

[Claims] Claim 1: A seal edge is formed on at least one of the drive side tooth surface and the non-drive side tooth surface at a position that does not come into contact with the seal edge of the other mating screw rotor. A screw rotor characterized by: