JPH021509Y2 - - Google Patents

Description

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

The present invention relates to a screw compressor, and more particularly, to a screw compressor that achieves high discharge pressure without increasing power consumption in a standard screw compressor.

[Technical background]

Screw compressors are designed and mass-produced to be directly connected to an engine or motor to obtain a predetermined discharge pressure (for example, 7 kg/cm ² ) with a constant output. However, some applications of such screw compressors may require higher discharge pressures than standard screw compressors. To address this in the simplest way,
The standard method is to use the screw compressor as is and simply adjust the unloader's set pressure upward to the required pressure value, but if you try to obtain a high discharge pressure with this method, the power consumption of the engine or motor will increase. increases. Therefore, a slightly larger engine or motor is required. In addition, at the design stage, we designed it as a special machine for high discharge pressure,
Manufacturing is also a commonly performed method. However, in any case, it is not a good idea because the advantage of commonality with the standard screw compressor is lost, economic efficiency has to be sacrificed, and mass production is not possible.

[Prior art and problems]

Therefore, the standard specification screw compressor,
It is conceivable that improvements could be made to obtain high discharge pressure without increasing power consumption. Japanese Patent Laid-Open No. 51-24906 discloses that in order to reduce the amount of gas passing through the compressor and increase the discharge pressure without changing power consumption, a cooperating rotor is used to extend the low pressure phase toward the normal compression section. A relief part is provided on the surface of the barrel in the operating area, with the periphery restricted by a screw line with the same lead angle as the tip of the compressor, which reduces the amount of gas passing through the compressor. Therefore, it is possible to reduce the compression volume and obtain a higher discharge pressure than the normal discharge pressure without increasing power consumption. However, in general, the pressure of the intake gas sucked into the working space of the screw compressor is in a negative pressure state lower than atmospheric pressure due to the resistance of the air cleaner and intake piping. The end face with the working space is circumferentially regulated by an end with a screw line having the same lead angle as the tip of the cooperating rotor, so the seal line drawn by the land tips of both the male and female rotors is a relief part. After passing through, the line of intersection of the cylinder is isolated from the low-pressure inlet, and the compression action starts from this point.At this time, when the suction gas is sucked into the working space, the suction gas remains as it is, with a large amount of Pressure state below atmospheric pressure (negative pressure state)
It gets sucked in. 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 present invention was developed to eliminate the drawbacks of the conventional machine and to obtain high discharge pressure without increasing power consumption with the standard screw compressor by making simple changes. , its characteristic is that two hollow cylinders 7 and 8 arranged in parallel form a pair that mesh with each other in the working space in the cylinder 6, which is formed by overlapping each other with circular parts of the cross sections perpendicular to the axis. In a screw compressor configured to house a male rotor 9 and a female rotor 10, suck gas from an inlet 16, compress it and discharge it from an outlet 22, two hollow cylinders are arranged in the cylinder 6 in the axial direction. A cutout groove 30 is formed at a portion that overlaps with one intersection line 23 of the partitions, and extends from the suction side end wall 2 communicating with the suction port in the direction of the discharge side end wall 4, communicating with the working space where the volume is the maximum. It's what I did.

[Effect]

Therefore, since the working space with the maximum volume is communicated with the suction port by the cutout groove 30, by delaying the start of the compression process of the intake gas, the compression working space, that is, the volume of the compression chamber is reduced, and the said working space is The amount of intake gas trapped within the space is also reduced. Therefore, the amount of discharged gas is also reduced, and the amount of work of the compressor associated with compression is also reduced by the amount of the intake gas, so that the discharge pressure can be increased with the same power consumption value. Further, the suction gas sucked into the notch groove by the distal end edges of the lands that mesh near the suction side end walls of both rotors 9 and 10 is also drawn in, increasing the suction action and efficiently supercharging the working space.

【Example】

The details of the present invention will be explained below based on the illustrated embodiments. 1 to 3, the screw compressor main body 1 has a cylinder 6 between a front casing 3 forming a suction side end wall 2 and a rear casing 5 forming a discharge side end wall 4. 6
The two hollow cylinders 7 and 8 arranged in parallel are overlapped with each other at circular portions of the axially perpendicular cross sections to form the working space of the cylinder. The working space of this cylinder accommodates a pair of screw rotors that mesh with each other, that is, a male rotor 9 and a female rotor 10, and both shaft ends of each rotor are rotatable by bearings 11, 12, 13, and 14 in the casings 3 and 5. One shaft end of the male rotor 9 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 bulging out the cylinder 6 to a slightly larger diameter than the hollow cylinders 7, 8 of the cylinder inner wall where the tips of the lands 18, 19 of both rotors 9, 10 are as close as possible to each other. 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 ends of the lands 18 and 19 and the inner wall of the cylinder 6. Normally, in the case of a standard screw compressor, the tips of the lands 18 and 19 of both rotors 9 and 10 are drawn as close as possible to the inner wall of the cylinder, and a pair of seal lines are drawn between the inner hole 17 and the suction passage 15. When the suction gas moves to the edge 21, which is the position where the communication is cut off, the intake gas is trapped in the working space 20 between the pair of seal lines and the other pair of seal lines preceding this, and compression starts. do. 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. The edge 21 of the inner hole 17 has a screw line having the same lead angle as the tips of the lands 18 and 19 of both rotors 9 and 10, and is located at a position where the volume of the working space 20 is theoretically maximum. It is formed at a position nearby. The present invention has a notch that communicates with the suction passage 15 in the portion where the two hollow cylinders 7 and 8 overlap at the line of intersection 23 on the suction side where both the male and female rotors 9 and 10 begin to mesh. This cutout groove 30 extends from the edge 21 of the inner hole 17 to the suction side end wall 2 below the plane of the paper of both rotors 9 and 10 in FIG. 1 and to the right in FIG.
It is provided in a substantially rectangular shape perforated in the 4 directions of the discharge side end wall. That is, as shown in FIG. 4, the end of the notched groove 30 in the axial direction toward the discharge port is located at the edge 21 of the inner hole 17, which is the normal suction confinement position.
The working space 21- is formed so as to protrude further toward the discharge side, delays the suction confinement position of the suction gas, and has a maximum volume even in the normal suction confinement position.
21 and c-c' are arranged at a position communicating with the suction passage 15. In addition, in accordance with the setting of the notch groove, the discharge port 22 is arranged as shown in FIG. 1, FIG. As shown by the solid line in the figure, it is opened at a position later than the standard specification discharge port 22' (represented by a dashed line in the figure), and the gas in the working space 20 is opened at a high discharge pressure that requires gas. When the pressure is increased, it is discharged through the discharge port 22. That is, the discharge start position is delayed compared to the standard specifications. Therefore, the suction gas that reaches the notch groove 30 via the suction port 16 and the suction passage 15 flows through the notch groove 30 and the inner hole 17.
Because it protrudes in the direction of the discharge side end wall from the edge 21 of the
Even after the seal lines b, b' drawn by the tip of the land 0 pass through the edge 21 of the inner hole, the lines 21-21 and c preceding the seal lines b, b' and d, d' pass through the notch groove 30. −c′, the working space 20 with the maximum volume
is in communication with the suction passage 15, so suction confinement is not yet performed, and suction is not completed until both rotors further rotate and the seal lines b, b' reach the positions of the dashed-dotted lines c, c'. The compression process begins. That is, the notch groove 30 delays the start of the compression process, and the volume of the compression chamber after the start of the compression process decreases, and as a result, the amount of intake gas decreases and the amount of discharged gas also decreases, so the amount of intake gas decreases. Accordingly, the amount of work of the compressor associated with compression is reduced, and compressed gas with a high discharge pressure can be obtained with the same power consumption value. Note that the position of the end of the notched groove 30 in the direction of the discharge port and the opening position of the discharge port are not limited to the illustrated embodiment, and can be arbitrarily selected as appropriate depending on the desired pressure of the compressed gas. Furthermore, even after the seal lines b and b' pass through the edge 21 of the inner hole in FIG.
When inhaling into the working space 20 formed by b', d, d', the gas in the notch groove 30 communicating with the suction passage on the suction side end face of both rotors 9, 10 is transferred to the land tip edge of both rotors 9, 10. Through the meshing of the two, the working space is efficiently supercharged. That is, as both the male and female rotors rotate, the trailing seal line of both the rotors is attached to the edge 21 of the inner hole.
-21, and the working space gradually becomes spaced until reaching the working space 21-21 and c-c' where the volume of the working space formed between the teeth and the seal line leading thereto is maximum. The volume is expanded, but during this expansion process, the working space is in a negative pressure state, so the pressure difference between this negative pressure and atmospheric pressure adds a flow velocity to the incoming intake gas, which increases the volume. The synergistic effect with the flow velocity caused by the high speed rotation of both the male and female rotors accelerates the flow velocity, resulting in the working spaces b-b' and c-c just before the suction confinement position c-c'. Efficient suction gas is supercharged into the working space within '.

【effect】

As described above, according to the present invention, a notched groove extending from the suction side end wall to the discharge side end wall is formed in the portion of the cylinder that overlaps the joining line of the two hollow cylinders,
Since the working space with the maximum volume is communicated with the suction port through this notched groove, the start of the compression process is delayed and the amount of suction gas sucked into the working space is reduced. Since the amount of gas is reduced, compressed gas with high discharge pressure can be obtained with the same power consumption value. Further, since the cutout groove can be directly formed from the suction side end wall, machining is easy. In addition, because the notched groove is provided at the line of intersection of the cylinder on the suction side where the male and female rotors begin to mesh, when gas is sucked into the working space, the negative pressure adds to the incoming suction gas at an appropriate flow rate. Since the intake gas is stirred by the gas flow rate accompanying the rotation of both the male and female rotors, this "scraping effect" allows gas to be efficiently supercharged into the working space, and thus, Inhalation efficiency can be improved. Therefore, it is possible to provide a practically useful and efficient screw compressor.

[Brief explanation of drawings]

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... Discharge port, 23... Intersection line, 30... Notch groove.

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. What is claimed is: 1. A screw compressor characterized in that a notched groove is formed extending from a suction side end wall to a discharge side end wall communicating with a working space and communicating with a suction port.