JPH021510Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

TECHNICAL FIELD The present invention relates to a screw compressor, and more particularly, to an improvement of a cylinder that increases the suction efficiency of a screw compressor.

[Technical background]

The screw compressor main body 1 is shown in Figures 1 to 4.
As shown in the figure, a cylinder 6 is provided between the front casing 3 forming the suction side end wall 2 and the rear casing 5 forming the discharge side end wall 4, and this cylinder 6 has two hollow cylinders 7 arranged in parallel. . A pair of mutually meshing screw rotors, a male rotor 9 and a female rotor 10, are accommodated in the working space of this cylinder, and both shaft ends of each rotor are connected to bearings 11, 12, 13, 14 in the casings 3, 5.
The male rotor 9 is rotatably supported by
One shaft end is directly connected to a rotating shaft of an engine or motor (not shown). A suction passage 15 is formed inside the front casing 3, and one end of the suction passage 15 communicates with a suction port 16, and the other end communicates with an inner hole 17 formed in the suction end wall side 2 of the cylinder 6. It's communicating. This inner hole 17 is formed by protruding the cylinder 6 to a slightly larger diameter than the hollow cylinders 7, 8 on the inner wall of the cylinder, to which the tips of the lands 18, 19 of both rotors 9, 10 are as close as possible. The inhaled gas is
Due to the meshing rotation of both the rotors 9 and 10, the air is sucked into a separate working space 20 formed between the tips of the lands 18 and 19 and the inner wall of the cylinder 6. Normally, a pair of seal lines a-a', in which the tips of the lands 18 and 19 of both the rotors 9 and 10 forming the working space 20 are drawn as close as possible to the inner wall of the cylinder, form the inner hole 17 and the suction passage. When moving to the edge 21 (double-dashed line), which is the position where communication with 15 is cut off,
Inhaled gas is trapped in the working space 20 between the pair of seal lines a-a' and the other pair of seal lines (bb') preceding them, and compression begins (see Figure 4). . That is, suction and confinement begin from the edge 21 of the inner hole 17, and the fluid is compressed and discharged from the discharge port 22.

[Prior art and problems]

In the conventional screw compressor, the edge 21 of the inner hole 17 (double-dashed line in FIGS. 1 and 4), which forms the suction cut-off position, has the same lead angle as the tips of the lands 18 and 19 of both rotors 9 and 10. The position where the volume of the working space 20 is theoretically maximum (seal line 21-21 and c-
(c' working space) or its vicinity, and generally due to the resistance of the air cleaner and intake piping, the pressure of the suction gas drawn into the working space of the screw compressor is in a negative pressure state lower than atmospheric pressure. After the seal line drawn by the ends of the lands of both the male and female rotors passes through the edge, the intersection line part of the cylinder is isolated from the suction port, and the compression action starts from this point. but,
At this time, when inhaling the suction gas into the working space,
The intake gas is sucked in as it is at a pressure below atmospheric pressure (negative pressure). For this reason, the suction efficiency is poor, the amount of discharged air is substantially reduced when converted to the suction state (atmospheric state), and the screw compressor has the drawback of poor volumetric efficiency.

【composition】

The purpose of the present invention is to increase the suction efficiency and the volumetric efficiency of the screw compressor by simply making simple improvements to the cylinder of the conventional machine. To explain, two hollow cylinders 7 arranged in parallel,
A pair of male rotors 9 and female rotors 10 that mesh with each other are housed in a working space in a cylinder 6 formed by overlapping each other with a circular part of a cross section perpendicular to the axis of each cylinder 8 , and gas is sucked from an inlet 16 . In a screw compressor configured to compress and discharge from a discharge port 22, the volume is the largest at a portion that overlaps one intersection line 23 that partitions the inside of the cylinder 6 into two hollow cylinders in the axial direction. A cutout groove 30 extending from the suction side end wall 2 to the discharge side end wall 4 direction, which communicates with the working space and the suction port 16, is formed, and an edge 31 of the inner hole 17, which communicates with the suction port, is defined. The suction closing position is provided at the end of the cylinder 6 in the direction of the suction side end wall 2 from the position where the volume of the working space formed between the lands of both rotors is maximum.

[Effect]

Therefore, the volume of the working space is gradually expanded until the working space reaches the maximum volume, but the suction defined by the edge of the inner hole 17 communicating with the suction port. The closing position is a position (lead line 31) earlier than the normal closing position where the volume of the working space formed between the lands of both rotors is at its maximum (lead line 31), and in the process of expanding the space volume, the working space is The inside of the space is in a negative pressure state, and the working space where the volume is maximum after the seal lines of both rotors pass through the edge 31 of the inner hole communicates with the suction passage only through the notch groove 30. Therefore, due to the pressure difference between the negative pressure and the atmospheric pressure, a flow velocity is added to the incoming suction gas, and at the same time, due to the high speed rotation of both the male and female rotors, the tip edge of the land that engages near the suction side end wall is generated. Due to the synergistic effect with the flow velocity, the flow velocity of the intake gas in the notched grooves on the line of intersection is accelerated, and as a result, efficient supercharging of the intake gas into the working space is performed.

【Example】

Hereinafter, with reference to FIGS. 1 to 4, the details of the present invention will be explained based on the illustrated embodiments, with respect to the differences from the prior art described above. That is, the present invention improves the conventional edge 21 of the inner hole 17.
(Figures 1 and 4, two-dot chain lines) are connected to both rotors 9 and 1.
The working space formed between the zero lands 18 and 19 is formed toward the suction side end wall from the position where the maximum volume is reached. In other words, the edge 31 of the inner hole 17 is formed in a curved shape corresponding to the twist line at the ends of the lands 18 and 19 of both rotors at a position earlier than the above position (lead line 31: solid line in FIGS. 1 and 4). is forming. In addition, a notch communicating with the suction passage 15 is provided on the suction side of the cylinder where the two rotors 9 and 10 start meshing, and at a portion that overlaps with the line of intersection 23 where the two hollow cylinders 7 and 8 formed in the cylinder 6 overlap. A groove 30 is formed. This notched groove 30 is formed by boring a cylinder 6 in a substantially rectangular shape from the suction end wall 2 to the discharge end wall 4 below the rotors 9 and 10 in FIG. 1 and to the right in FIG. 3. It is provided. That is, as shown in FIG. 4, the end of the notch groove 30 in the axial direction toward the discharge port is aligned with the seal line b-
The edge 2 of the inner hole 17, which is the normal suction confinement position that communicates the working spaces b' and d-d' with the suction passage.
It is formed to protrude further toward the discharge side than 1, delays the suction confinement position of the suction gas, and creates an action space (21-21 and c-c') where the volume is maximum even in the normal suction confinement position. It is provided at a position communicating with the passage 15. Note that the position of the end of the notched groove 30 in the discharge port direction is not limited to the illustrated embodiment, and can be arbitrarily selected as appropriate depending on the desired pressure of the compressed gas. Further, 22 is a discharge port for compressed gas. Next, the operation of the above embodiment will be explained. In FIG. However, the working space (a-a' and b-b')
is the volume formed by the seal lines 21-21 and c-c' after the seal lines of both rotors have passed through the edge 31 of the bore and preceding the seal lines b-b' and d-d'. Since the notch groove 30 protrudes toward the discharge side end wall from the edge 21 of the conventional inner hole 17, the working space 20, which is the maximum, communicates with the suction passage 15 only through the notch groove 30, and is still in communication with the suction passage 15. Since suction confinement does not occur and the working space whose volume is gradually expanded is under negative pressure during the expansion process, the incoming suction gas has a flow rate due to the pressure difference between this negative pressure and atmospheric pressure. is added, and the notch groove 30
The intake gas is supercharged through the intake port 16 and the intake passage 15. Furthermore, due to the synergistic effect of the flow velocity generated by the high-speed rotation of both the male and female rotors, which generate the leading edge of the land that engages near the suction side end wall, the flow velocity of the suction gas in the notched groove on the line of intersection is accelerated. Efficient supercharging of suction gas to the working spaces b-b' and c-c' immediately before the suction confinement position c-c' is carried out by sucking the gas in the notch groove 30. . Then, due to the rotation of both rotors 9 and 10, the seal line b-b' becomes the seal line after the discharge side end of the notched groove,
Only after passing through the dashed-dotted line c-c' is the action space b
-b' and dd' are cut off from communicating with the suction passage;
The intake gas is trapped and the compression process by both rotors begins. The suction gas passes through each working space formed between the lands of both rotors, which are gradually reduced in size, is compressed to a desired pressure, and is discharged to the outside from the discharge port 22.

【effect】

As described above, the present invention forms the edge of the inner hole provided in the cylinder, which is the gas suction cut-off position in the screw compressor, between the lands of both rotors that mesh and rotate in the cylinder where the edge is normally provided. The volume of the working space is the maximum at a portion that is provided toward the suction side end wall from the position where the volume of the working space is maximum, and overlaps with one intersection line that partitions the inside of the cylinder into two hollow cylinders in the axial direction. Since a cutout groove is provided that extends from the suction side end wall communicating with the suction port to the discharge side end wall, the seal line of both the male and female rotors and the edge of the inner hole communicating with the suction port are provided. Due to the early suction deadline of the working space defined by the parts, the working space with the largest volume communicates with the suction port only through the notched groove, and when gas is sucked into the working space, the negative pressure The suction gas is stirred by the moderate flow velocity applied to the inflowing suction gas and the gas flow velocity accompanying the rotation of both the male and female rotors, and this "scraping effect" efficiently moves the gas into the working space. Supercharging can be performed, thus improving suction efficiency. Therefore, it is possible to provide a practically useful and efficient screw compressor. Further, since the cutout groove can be directly formed from the suction side end wall, machining is easy.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, in which Fig. 1 is a cross-sectional view of the main body of the screw compressor, Fig. 2 is a longitudinal sectional view thereof, Fig. 3 is a sectional view taken along the line of Fig. 1, and Fig. 4 is a cross-sectional view of the main body of the screw compressor. is a developed view of the cylinder. 1...Screw compressor main body, 2...Suction side end wall, 3...Front casing, 4...Discharge side end wall,
5... Rear casing, 6... Cylinder, 7, 8... Hollow cylinder, 9... Male rotor, 10... Female rotor, 1
1, 12, 13, 14... bearing, 15... suction passage,
16... Suction port, 17... Inner hole, 18, 19... Land, 20... Working space, 21... Edge, 22... Outlet, 23... Intersection line, 30... Notch groove, 31... Edge of inner hole of the present invention Department.

Claims (1)

[Scope of utility model registration request] A pair of male and female rotors that engage with each other are accommodated in the working space in the cylinder, which is formed by overlapping each other with circular parts of the cross sections perpendicular to the axis of two hollow cylinders arranged in parallel, and gas is introduced from the inlet. In a screw compressor configured to suck in air, compress it, and discharge it from a discharge port, the volume is at its maximum at a portion that overlaps one intersection line that partitions the inside of the cylinder into two hollow cylinders in the axial direction. A notched groove extending from the suction side end wall toward the discharge side end wall communicating with the suction port is formed, and the suction closing position defined by the edge of the inner hole communicating with the suction port is defined by the suction closing position. A screw compressor characterized in that the screw compressor is provided at the end of the cylinder in the direction of the suction side end wall from the position where the volume of the working space formed between the lands of both rotors is maximum.