JP6276118B2 - Screw compressor - Google Patents

Description

  The present invention relates to a screw compressor.

  In a screw compressor, it is known that pressure pulsation occurs due to a frequency determined by the product of the male rotor rotational speed and the number of screw teeth and its higher order components by performing compression. This pressure pulsation acts on the compressor body as an exciting force, and vibrates the rotor casing. This vibration changes the amount of clearance between the rotor and the rotor casing covering the periphery of the rotor.

  The gap between the rotor and the rotor casing has a great influence on the compressor performance. In addition, when the gap is narrowed, the rotor and the rotor casing come into contact with each other, causing performance degradation and damage.

  Patent Document 1 discloses a rotor casing having a constricted accommodating portion and having an outer wall surface formed so that the thickness of the constricted position is larger than that of other portions. This outer wall surface is formed for vibration countermeasures.

  However, increasing the thickness of the rotor casing leads to a significant increase in manufacturing costs.

Japanese Patent Laid-Open No. 08-247034

  An object of the present invention is to reduce vibration during operation of a screw compressor and prevent performance degradation and breakage without significantly increasing manufacturing costs.

As a means for solving the above problems, a screw compressor according to the present invention includes a pair of housing portions that house a pair of male and female screw rotors, a rotor casing having an intake port that communicates with the pair of housing portions, and the intake port. A suction space provided so as to surround; a main body casing having an air inlet that communicates the suction space with the outside; and a connecting portion that is disposed in the suction space and connects the rotor casing and the main body casing. The intake port is disposed at a side portion of the main body casing, the intake port is disposed at an axial intake port disposed at an end portion of the rotor casing in an axial direction of the screw rotor, and at a side portion of the rotor casing. A radial intake port disposed, wherein the connecting portion is located between the axial intake port and the radial intake port. Are arranged along the radial air supply port is disposed.

  According to this configuration, since the connecting portion is disposed in the suction space and the rotor casing and the main body casing are connected, it is possible to prevent the rotor casing from vibrating greatly when the screw compressor is operated. That is, vibration during operation of the screw compressor can be reduced. Thereby, it can suppress that the amount of clearance gaps between a screw rotor and a rotor casing changes. That is, it is possible to prevent the performance degradation and breakage of the screw compressor. Therefore, it is possible to eliminate the necessity of increasing the thickness of the main casing as a vibration countermeasure. Moreover, the necessity for improving the rigidity of a main body casing by adding components can be excluded. That is, vibration during operation of the screw compressor can be reduced and performance degradation and breakage can be prevented without significantly increasing the manufacturing cost.

  According to the present invention, it is possible to reduce vibration during operation of the screw compressor and prevent performance degradation and breakage without significantly increasing the manufacturing cost.

Sectional drawing which shows the principal part of the screw compressor of 1st Embodiment concerning this invention. The radial direction sectional view showing the rotor casing and suction space of the screw compressor of a 1st embodiment. The front perspective view of the main body casing of the screw compressor of a 1st embodiment. The rear perspective view of the main body casing of the screw compressor of a 1st embodiment. The rear perspective view of the main body casing of the screw compressor of a 1st embodiment. VV sectional view taken on the line of FIG. FIG. 6 is a sectional view taken along line VI-VI in FIG. 2. The upper perspective view of the main body casing of the screw compressor of a 2nd embodiment. Sectional drawing which shows the position of the connection part of the screw compressor of 2nd Embodiment. The upper perspective view of the main body casing of the screw compressor of a 3rd embodiment. The upper perspective view of the main body casing of the screw compressor of a 4th embodiment. Sectional drawing which shows the principal part of the screw compressor of 5th Embodiment. Radial direction sectional drawing of the screw compressor of 5th Embodiment which abbreviate | omitted illustration of the connection part. The upper perspective view which cut off some main body casings so that the connection part and intake port in the screw compressor of 5th Embodiment could be seen. The top view which cut off a part of main body casing so that the connection part and radial direction intake port in the screw compressor of 5th Embodiment could be seen. The front perspective view of the main body casing of the screw compressor of a 5th embodiment. The rear perspective view of the main body casing of the screw compressor of a 5th embodiment. The upper perspective view which shows the main body casing of an analysis model. The perspective view which shows the analysis position of a rotor casing. The figure which shows the relationship between the position and maximum displacement in an analysis model. The perspective view which shows the analysis position of a rotor casing. The figure which shows the relationship between the position and maximum displacement in an analysis model.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a main part of a screw compressor 10 according to a first embodiment of the present invention. A suction space 12 is provided inside the main casing 11. As shown in FIGS. 2 and 3, the suction space 12 is formed in a horizontally long cylindrical shape and extends in the axial direction. As shown in FIGS. 4A and 4B, the side wall (side part) 11 a of the main body casing 11 is provided with an intake port 13 that communicates the suction space 12 with the outside and sucks gas into the suction space 12.

  As shown in FIG. 5, the main body casing 11 is provided with a rotor casing 15 in which a pair of male and female screw rotors 14 </ b> A and 14 </ b> B is disposed. As shown in FIG. 1, the rotor casing 15 is disposed in the suction space 12 and is supported on the entire circumference by one end (end portion) 16 of the screw rotor 14 in the axial direction. As shown in FIGS. 1 to 3, at the other end (end portion) 17 in the axial direction of the screw rotor 14, the rotor casing 15 is connected to the housing portions 19 </ b> A and 19 </ b> B on the side opposite to the intake port 13 side. Connected by. That is, the rotor casing 15 is connected at the end 17 at a part of the entire circumference. In this specification, the end 17 side is the front side, and the end 16 side is the back side.

  As shown in FIGS. 1 to 3, an intake port (axial intake port) 18 is provided at an end 17 of the rotor casing 15 in the axial direction of the screw rotor 14. The intake port 18 is an opening for sucking gas from the suction space 12 in a direction substantially parallel to the axial direction of the screw rotor 14. The intake port 18 communicates with the pair of accommodating portions 19A and 19B. The intake port 18 and the side portion 15 a on the intake port 18 side are adjacent to and surrounded by the suction space 12.

  Inside the rotor casing 15, a pair of accommodating portions 19 </ b> A and 19 </ b> B that accommodate a pair of male and female screw rotors 14 </ b> A and 14 </ b> B are provided. In FIG. 1, only one screw rotor 14 and one accommodating portion 19 appear. The accommodating portions 19 </ b> A and 19 </ b> B on the end portion 16 side are closed by the main body casing 11. An insertion hole 25 through which the rotor shaft 24 of the screw rotor 14 is inserted is provided in the main body casing 11 which is the end portion 16 of the accommodating portion 19.

  As shown in FIGS. 1, 5, and 6, a discharge portion 22 that discharges the compressed gas in the housing portion 19 is provided on the one end 16 side of the rotor casing 15 of the main body casing 11. As shown in FIGS. 1 and 6, the main body casing 11 is provided with a discharge space 26 adjacent to the discharge portion 22. As shown in FIG. 3, the discharge space 26 communicates with the outside through a discharge port 27 provided on the side wall 11 a opposite to the intake port 13.

  As shown in FIGS. 1 and 2, a suction space defining portion 21 that defines the suction space 12 so as to surround the intake port 18 is provided on the end 17 side of the main casing 11 as shown in FIG. 13. It is provided similarly. The rotor shafts 24 </ b> A and 24 </ b> B on the end portion 17 side are supported by the suction space defining portion 21.

  As shown in FIG. 3, the suction space 12 on the back side on the left and right sides of the connection wall 20 is defined by partition walls 28 </ b> A and 28 </ b> B. The connection wall 20 is connected to the partition walls 28A and 28B. As shown in FIG. 6, a cooling jacket 29 is provided between the partition walls 28 </ b> A and 28 </ b> B of the main casing 11 and the discharge space 26.

  As shown in FIGS. 3 and 4A, a connecting portion 23 formed in a columnar shape is disposed in the suction space 12 on the intake port 13 side when the screw rotor 14 (not shown) is viewed in the axial direction. An end portion of the connecting portion 23 is connected to an intermediate portion in the axial direction of the side portion 15 a of the rotor casing 15. The connecting portion 23 extends in a direction substantially orthogonal to a plane including the axis of the accommodating portion 19A and the axis of the accommodating portion 19B. The connecting portion 23 connects the rotor casing 15 and the main body casing 11. That is, it can be said that the rotor casing 15 is supported by the main body casing 11 by the connecting portion 23, and that the main body casing 11 is supported by the rotor casing 15.

  As shown in FIGS. 3 and 6, the gas sucked from the intake port 13 flows into the suction space 12 and flows into the rotor casing 15 through the intake port 18. The gas that has flowed in is compressed by a pair of male and female screw rotors 14A and 14B and is discharged from the discharge portion 22 to the discharge port 27 through the discharge space 26.

  In the screw compressor 10, pressure pulsation is generated due to the frequency determined by the product of the male rotor rotational speed and the number of screw teeth and its higher order components by performing compression. This pressure pulsation vibrates the main casing 11 as an excitation force.

  As shown in FIG. 1, in the main body casing 11 of the screw compressor 10 having the intake port 18 installed in the rotor casing 15 on the axial direction side of the screw rotor 14, the intake port 13 is provided on the radial side of the screw rotor 14. . Therefore, it is necessary to connect the intake port 18 on the axial direction side and the intake port 13 on the radial direction side through the suction space 12. When this structure is adopted, the rotor casing 15 is supported by the end 16 over the entire circumference. When the screw compressor 10 is an oil-free screw compressor, it is necessary to provide the cooling jacket 29 on the discharge port 27 side as shown in FIGS. 1 and 3, so that the connection is made on the discharge port 27 side of the end portion 17. Connected by a wall 20. However, since the end portion 17 is surrounded by the suction space 12, when the connecting portion 23 is not provided, the end portion 17 is likely to vibrate greatly due to pressure pulsation.

  However, according to the present invention, as shown in FIGS. 1 and 3, the connecting portion 23 is disposed in the suction space 12 on the intake port 13 side to connect the rotor casing 15 and the main body casing 11. It is possible to prevent the rotor casing 15 from vibrating greatly in the suction space 12 side, that is, in the radial direction when the compressor 10 is operated. That is, vibration during operation of the screw compressor 10 can be reduced. Thereby, it can suppress that the amount of clearance gaps between the screw rotor 14 and the rotor casing 15 changes. That is, the performance degradation of the screw compressor 10 can be prevented. Therefore, it is possible to eliminate the necessity of increasing the thickness of the main casing 11 as a countermeasure against vibration. Moreover, the necessity for improving the rigidity of the main body casing 11 by adding components can be eliminated. That is, vibration during operation of the screw compressor can be reduced and performance degradation and breakage can be prevented without significantly increasing the manufacturing cost.

  Further, as shown in FIGS. 1 and 3, a main body casing in which the intake port 18 is disposed at the end portion 17 of the rotor casing 15 in the axial direction of the screw rotor 14 and the intake port 13 is opposed to the side portion 15 a of the rotor casing 15. The screw compressor 10 arrange | positioned at 11 side parts 11a can be comprised. By disposing the intake port 13 on the side portion 11 a of the main body casing 11, an increase in the axial dimension of the main body casing 11 can be avoided.

  Further, as shown in FIGS. 1 and 3, since the connecting portion 23 is disposed on the intake port 13 side in the axial direction view of the screw rotor 14, they are opposed to each other via the suction space 12 on the intake port 13 side. The rigidity of the rotor casing 15 and the main body casing 11 can be increased. Therefore, vibration generated in the rotor casing 15 in a region adjacent to the suction space 12 on the intake port 13 side can be reduced intensively.

(Second Embodiment)
FIG.7 and FIG.8 shows the main body casing 11 of the screw compressor 10 of 2nd Embodiment. The connecting portion 23 is formed in a prismatic shape. The connecting portion 23 is disposed along the end portion 17 of the rotor casing 15 in a direction intersecting the axial direction of the screw rotor 14 (not shown). In more detail, the connection part 23 is provided in the edge part 17 of the side part 15a of the accommodating part 19B near the inlet port 13. The connecting portion 23 extends in a direction substantially orthogonal to a plane including the axis of the accommodating portion 19A and the axis of the accommodating portion 19B.

  According to this configuration, since the connecting portion 23 is disposed along the end portion 17 of the rotor casing 15 in a direction intersecting with the axial direction of the screw rotor 14, the end portion 17 of the rotor casing 15 in which the vibration displacement is maximized. Can be reduced intensively.

  Other configurations and operations of the second embodiment are the same as those of the first embodiment.

(Third embodiment)
FIG. 9 shows the main body casing 11 of the screw compressor 10 of the third embodiment. The connecting portions 23A and 23B are formed in a prismatic shape. The connecting portions 23A and 23B are arranged in a plurality of locations (two locations in the present embodiment). More specifically, one connecting portion 23A is disposed at the end portion 17 of the side portion 15a of the accommodating portion 19A, and the other connecting portion 23B is disposed at the end portion 17 of the side portion 15a of the accommodating portion 19B.

  According to this structure, the vibration reduction effect of the screw compressor 10 obtained by providing the single connection part 23 can be obtained with a smaller material weight. Thereby, the raise of suction resistance and the increase in operating cost can be suppressed.

  Other configurations and operations of the third embodiment are the same as those of the second embodiment.

(Fourth embodiment)
FIG. 10 shows the main body casing 11 of the screw compressor 10 of the fourth embodiment. The connecting portion 23 is formed in a substantially rectangular flat plate shape. The air inlet 13 is disposed on the side portion 11a so as to face the one accommodating portion 19B, and the connecting portion 23 is disposed on the other accommodating portion 19A. Therefore, the connecting portion 23 can be disposed in the accommodating portion 19A far from the intake port 13 at a position away from the flow path where the gas flow rate is relatively high, and an increase in gas suction resistance can be suppressed.

  Other configurations and operations of the fourth embodiment are the same as those of the second embodiment.

(Fifth embodiment)
11 to 14 show a screw compressor 10 of the fifth embodiment. The intake port includes an axial intake port 181 and a radial intake port 182. The axial suction port 181 is an opening for sucking gas from the suction space 12 in a direction substantially parallel to the axial direction of the screw rotor 14. The axial intake port 181 is the same as the intake port 18 of the first embodiment, and is disposed at the end 17 of the rotor casing 15 in the axial direction of the screw rotor 14. The radial intake port 182 is an opening for sucking gas from the suction space 12 in a direction substantially perpendicular to the axial direction of the screw rotor 14. The radial intake port 182 is disposed on the side portion 15 a of the rotor casing 15. As shown in FIG. 14, the radial intake port 182 is substantially rectangular in plan view. The connecting portion 23 is formed in a substantially rectangular flat plate shape. The connecting portion 23 is disposed between the radial intake port 182 and the axial intake port 181 in the axial direction of the screw rotor 14.

  More specifically, as shown in FIGS. 14 to 16, the connecting portion 23 is disposed along the end portion 17 of the side portion 15 a of the rotor casing 15. The radial intake port 182 is disposed along the connecting portion 23. When viewed in the axial direction of the screw rotor 14, the connecting portion 23 has substantially the same width as that of the radial intake port 182. In addition, in FIG. 12, illustration of the connection part 23 is abbreviate | omitted.

  According to this configuration, since the connecting portion 23 is disposed along the radial intake port 182 of the side portion 15a of the rotor casing 15, the radial intake port 182 is provided on the side portion 15a of the rotor casing 15. The rigidity of the lowered side portion 15a of the rotor casing 15 can be increased. Therefore, vibration during operation of the screw compressor 10 can be effectively reduced.

  Further, the connecting portion 23 is provided in the main body casing 11 so as to have substantially the same width as the radial intake port 182 when the screw rotor 14 is viewed in the axial direction. Therefore, it is possible to rectify the gas sucked from the intake port 13 and to suppress a large amount of the gas from moving to the axial intake port 181. In other words, intake from the radial intake port 182 is facilitated, and performance degradation of the screw compressor 10 can be prevented.

  Other configurations and operations of the fifth embodiment are the same as those of the second embodiment.

  In order to demonstrate the vibration reduction effect, numerical analysis was performed using an analysis model with the following set conditions.

[Common conditions]
-Axial intake port: Existent-Radial intake port: Existence-Distance between rotor casing end and radial intake port L1: 0.1 Lmm
・ Length of radial intake port L2: 0.55Lmm
・ Width W of radial direction intake port: 0.5Lmm
・ Connection wall: Existence [Setting condition 1]
The main body casing shown in FIG. 17 according to the present invention.
-Rotor casing thickness: t (mm)
・ Connecting part: Existence [Setting condition 2]
Main body casing equivalent to Condition 1 except that no connecting portion is provided.
-Rotor casing thickness: t (mm)
・ Connecting part: None (no stiffening)
[Setting condition 3]
A main body casing equivalent to condition 2 except that the thickness of the rotor casing is changed to 1.3 t (mm).
-Rotor casing thickness: 1.3t (mm)
・ Connecting part: None (no stiffening)

  In the rotor casing 15 of the analysis model shown in FIG. 18, the direction is located on the side portion 15a of the accommodating portion 19B that accommodates the female rotor 14B and is parallel to the axial direction of the female rotor 14B along the radial intake port 182. A plurality of points located on a line (thick dotted line) extending in the direction was sampled. In FIG. 19, the maximum displacement δ (m) at each position x (m) of a plurality of sampled points is plotted. The point on the end 17 side (suction end face side) on the thick dotted line is P (x = −L), and the point on the end 16 side (discharge end face side) is Q (x = 0). The coordinate axis in the right part of FIG. 18 corresponds to the position x (m) on the thick dotted line. The points on the line segment PQ excluding the point Q are located in the region of x <0.

In FIG. 19, the maximum displacement δ (m) at each position x (m) of the rotor casing analysis model of the setting condition 1 (the present invention), the setting condition 2 and the setting condition 3 is plotted with ◯, ■, and △. Has been. In the region on the discharge end face side (point Q side) located at the end portion 16, the value of the maximum displacement δ (m) of each setting condition does not change greatly, but the suction end face side (point P side) located at the end portion 17 It can be seen that there is a large difference in the value as it goes to. At the point P, the maximum displacement δ of the rotor casing under the setting conditions 1, 2 and 3 is 0.55 × 10 ⁻⁵ (m), 6.1 × 10 ⁻⁵ (m), 3 4 × 10 ⁻⁵ (m).

According to the above results, at the point P (x = −L), the maximum displacement δ (= 0.55 × 10 ⁻⁵ (m)) of the rotor casing analysis model of the setting condition 1 (present invention) is the setting condition. 2 is about 1/10 of the maximum displacement δ (= 6.1 × 10 ⁻⁵ (m)) of the rotor casing analysis model. That is, by adding the connecting portion 23 of the present invention to the main body casing 11 having the same thickness (= t (mm)), the vibration displacement is reduced to about 1/10 on the suction end face side (end portion 17 side) where the vibration displacement is large. Can be reduced.

At point P (x = −L), the maximum displacement δ (= 0.55 × 10 ⁻⁵ (m)) of the rotor casing analysis model under the setting condition 1 (the present invention) is It is about 1/6 of the maximum displacement δ (= 3.4 × 10 ⁻⁵ (m)). That is, the maximum displacement δ of the rotor casing under the setting condition 1 (the present invention) is the maximum displacement δ of the rotor casing of the main body casing having a thickness (= t (mm)) increased by 1.3 times without providing a connecting portion. On the other hand, vibration displacement can be reduced to about 1/6 on the suction end face side (end portion 17 side).

FIG. 20 shows the position of the cusp portion 30 (thick dotted line) on the intake port 13 side of the accommodating portions 19A and 19B where a plurality of points are sampled. The cusp part 30 is a connecting part of the accommodating parts 19A and 19B. As shown in FIG. 21, in the region on the discharge end face side (point Q side) located at the end portion 16, the value of the maximum displacement δ (m) of each setting condition does not change greatly, but is located at the end portion 17. It can be seen that there is a large difference in the above values toward the suction end face side (point P side). At the point P, the maximum displacement δ of the rotor casing under the setting conditions 1, 2 and 3 is 0.75 × 10 ⁻⁵ (m), 1.25 × 10 ⁻⁴ (m), 6 respectively. 60 × 10 ⁻⁵ (m). In FIG. 21, a region where no value is plotted is a region of the radial direction intake port 182.

According to the above results, at the point P (x = −L), the maximum displacement δ (= 0.75 × 10 ⁻⁵ (m)) of the rotor casing analysis model of the setting condition 1 (present invention) is the setting condition. 2 or less of the maximum displacement δ (= 1.25 × 10 ⁻⁴ (m)) of the rotor casing analysis model 2. That is, by adding the connecting portion 23 of the present invention to the main body casing 11 having the same thickness (= t (mm)), the vibration displacement is reduced to 1/10 or less on the suction end surface side (end portion 17 side) where the vibration displacement is large. Can be reduced.

At point P (x = −L), the maximum displacement δ (= 0.75 × 10 ⁻⁵ (m)) of the rotor casing analysis model under the setting condition 1 (the present invention) is It is 1/6 or less of the maximum displacement δ (= 6.60 × 10 ⁻⁵ (m)). That is, the maximum displacement δ of the rotor casing under the setting condition 1 (the present invention) is the maximum displacement δ of the rotor casing of the main body casing having a thickness (= t (mm)) increased by 1.3 times without providing a connecting portion. On the other hand, vibration displacement can be reduced to 1/6 or less on the suction end face side (end portion 17 side).

  From the above, the same vibration reducing effect was confirmed in both the side portion 15a of the accommodating portion 19B that accommodates the female rotor 14B and the cusp portion 30 on the intake port 13 side of the accommodating portions 19A and 19B.

  According to the present invention, the vibration of the screw compressor 10 can be reduced, so that contact between the rotor 14 and the rotor casing 15 can be avoided even if the gap between the rotor 14 and the rotor casing 15 is reduced. Since the gap between the rotor 14 and the rotor casing 15 can be reduced, the performance of the screw compressor 10 can be improved.

  In addition, the screw compressor 10 of this invention is not limited to the structure of the said embodiment, A various change is possible so that it may illustrate below.

  The connecting portion 23 may have any cross-sectional shape including an ellipse and a polygon.

  In 3rd Embodiment, the connection part 23 may be divided and provided in three or more places.

  The present invention can also be applied to the screw compressor 10 that does not have the connection wall 20.

DESCRIPTION OF SYMBOLS 10 Screw compressor 11 Main body casing 11a Side wall (side part) of main body casing
12, 12A, 12B Suction space 13 Inlet port 14, 14A, 14B Screw rotor 15 Rotor casing 15a Side of rotor casing 16 One end of rotor casing 17 Other end (end) of rotor casing
18 Intake port (Axial intake port)
19, 19A, 19B accommodating portion 20 connection wall 21 suction space defining portion 22 discharge portion 23, 23A, 23B connecting portion 24, 24A, 24B rotor shaft 25 insertion hole 26 discharge space 27 discharge port 28, 28A, 28B partition wall 29, 29A 29B Cooling jacket 30 Cusp part 181 Axial intake port 182 Radial intake port

Claims (3)

A rotor casing having a pair of housing portions for housing a pair of male and female screw rotors, an intake port communicating with the pair of housing portions, a suction space provided so as to surround the suction port, and the suction space and the outside A main body casing having an intake port in communication;
A connecting portion that is disposed in the suction space and connects the rotor casing and the main body casing;
The intake port is disposed on a side portion of the main body casing,
The intake port includes an axial intake port disposed at an end of the rotor casing in the axial direction of the screw rotor, and a radial intake port disposed at a side of the rotor casing,
The connecting portion is a screw compressor , wherein the connecting portion is disposed and disposed along the radial air supply port between the axial intake port and the radial intake port . The screw compressor according to claim 1, wherein the connecting portion has a flat plate shape. The screw compressor according to claim 2, wherein the connecting portion has the same width as the radial air supply port in the axial view of the screw rotor.

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