JPS6332389Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a screw compressor with a capacity control slide valve that compresses gas by rotating a pair of screw rotors that mesh with each other within a rotor chamber.

Conventionally, the slide valve for capacity control of this type of screw compressor is shown in FIG. 1 which is a vertical sectional view of the screw compressor, FIG. 3 which is a BB sectional view of FIG. 1, and partially enlarged view of FIG. 3. As shown in FIG. 5 for explanation, an arcuate guide 32' is provided in the axial direction on a part of the rotor casing wall, and is guided by this guide surface and is spaced from the outer periphery of the male rotor 4 and female rotor 5. By moving in the axial direction, the discharge amount of the screw compressor is adjusted.

Although the gap between the slide valve 32 and the guide 32' is small, the contact angle ΘM,
Since ΘF is small, the vertical clearances SM and SF are quite large. The meshing screws of both rotors 4 and 5 closer to the suction port side are moving toward each other on their outer peripheries, and the two rotors 4 and 5 on the side closer to the suction port side of the slide valve 32 are approaching each other. The side is under pressure close to the suction pressure, and the gas on the discharge side goes around the gap between the slide valve 32 and the rotor casing 1 on the opposite side that is in contact with both rotors 4 and 5 and flows to the suction port side. Therefore, due to pressure fluctuations, the side of the slide valve 32 closer to the suction port moves upward by the amount of the gaps SM and SF, and comes into contact with the male rotor 4 and female rotor 5, damaging both rotors and increasing gas leakage. This resulted in a decrease in volumetric efficiency. The invention disclosed in Japanese Patent Publication No. 45-8590 provides a roller guide by providing an axial groove on the outer periphery of the slide valve on the side that contacts the casing. In this way, rotation of the slide valve about its axis can be stopped, but there are problems similar to those described above.

In response to these, various means have been proposed to prevent the upward movement of the slide valve. For example, in the device disclosed in Japanese Utility Model Application Publication No. 55-140781, guide grooves are provided on both sides of the slide valve in the horizontal direction (axial direction), and guide pins attached to the casing are respectively fitted into the guide grooves. In this way, the parallelism and indexing (division of the circumference) accuracy of the guide grooves must be achieved at separate positions on both sides of the slide valve, which makes machining (difficult). Since a hole must be drilled into which the guide pin will be driven, it is difficult to process and it is especially difficult to provide the hole in an accurate position.

The purpose of this invention is to prevent floating in the slide valve of a screw compressor as described above, and to improve reliability and efficiency.

This invention is a screw compressor in which both the slide valve and the rotor casing are connected to the bottom of the guide formed in the slide valve and the rotor casing in the axial direction of the slide valve, instead of the conventional guide block that prevents rotation of the slide valve. A new guide block is provided to stop the rotor casing, and the guide block is fitted into the slide valve and the rotor casing, respectively, to prevent relative displacement between the two above, and the slide valve and guide block are made slidable.

Embodiments of the present invention will be described below with reference to the drawings. The drawings all show screw compressors.
FIG. 2 is a sectional view taken along the line AA in FIG. 1.

Both sides of the rotor casing 1 form a suction side end wall and a discharge side end wall, which are sealed by a suction casing 2 and a discharge casing 3, and a male rotor 4 and a female rotor 5 having shapes as shown in FIG. 3 are engaged with each other. Both rotors are in contact with the bicircular arc-shaped outer periphery of the casing 1 on the discharge side. When both rotors rotate in the direction of the arrow shown in the figure, the positions where they engage each other gradually move even though they have the same lead.The male rotor 4 and female rotor 5, which engage with each other by providing thread grooves and threads with large leads on their outer peripheries, The integrated shaft portion 4a,
4b, 5a, 5b are supported in the radial direction by journal bearings 6, 7 fitted into the suction casing 2, respectively, and journal bearings 8, 9 fitted into the discharge casing 3, respectively, and thrust ball bearings 12, fitted into the discharge casing 3. The shaft portion 4a of the male rotor 4 and the shaft portion 5a of the female rotor 5 are fitted into the inner ring 13, and their axial movement is restrained by nuts 14 and 15 screwed into the respective shaft portions between them and the stepped portions. has been done.

An integral shaft portion 4a of the male rotor 4 projects outside the machine to form a shaft end portion 4c, and the male rotor 4 is driven by the shaft end portion 4c.

The shaft portion 4a is sealed by a shaft sealing device 18 such as a mechanical seal in a seal cover 17 fixed to a cover 16 fixed to the discharge casing 3. A liner ring 19 is also driven into the cover 16 at a portion through which the shaft portion 4a passes. A hydraulically actuated piston 37 for balancing the thrust of the male rotor 4 and the female rotor 5 is provided at the end of the shaft portion 4b.

The two ends of the suction casing are covered by a cover 21.

A suction passage 22 is provided in the upper part of the suction casing 2, and a suction port 23 is opened at a position on the upper end surface between the male rotor 4 and the female rotor 5. A discharge port 24 is provided on the end surface of the discharge casing 3 opposite to the position below the suction port 23 where the male rotor 4 and the female rotor 5 meet, and a discharge passage 25 in the discharge casing 3 communicates with the outside of the machine. ing.

A cylinder 26 is fitted into the suction casing 2 and the cover 21 and is held down by a cover 27.

A piston 28 sealed by a sealing ring 29 is fitted into the cylinder 26, and the piston rod 31 changes the suction side volume extended into the rotor casing 1 through the sealing ring 33 fitted into a hole in the suction casing 2. It is fixed to a slide valve 32 that adjusts the suction amount by adjusting the suction amount.

The cylinder 26 is covered by a cover 27 fixed to the cover 21, and the piston rod 31 passes through a sealing ring 33' inserted into a hole in the cover 27 and comes out. The suction amount is controlled by detecting the position of the 34 and 35 are cylinder 2
6 is the pressure oil inlet/outlet.

When the shaft end 4c rotates the male rotor 4 as shown by the arrow in FIG. 3, the female rotor 5 engages with the male rotor 4.
rotates at the same speed in the opposite direction. These rotation speeds are rotated at high speed by an electric motor with a synchronous speed of about 3000 rpm, as an example.

When the male rotor 4 and female rotor 5 rotate, they pass through the suction passage 22 from piping (not shown) and from the suction port 23 to the rotor casing 1, male rotor 4, and female rotor 5.
Gas is sucked into the suction space formed by
The gas is compressed as the volume between the male rotor 4, female rotor 5 and the casing gradually decreases, is discharged at the discharge port 24, and is sent to the discharge side piping through the discharge passage 25.

FIG. 4 is a partially enlarged view of FIG. 3. The slide valve 32 is fitted into a guide 32' having an arcuate cross section so as to be movable in the axial direction. A T-groove 41 is formed in the lower part of the slide valve 32 over the entire length of the slide valve 32, and the inner surface of the jaw of the T-groove 41 is finished to be parallel to the axis of the slide valve 32 in the axial direction with high accuracy.

A T-slot 42 is formed on the discharge-side end wall side of the guide 32' of the rotor casing 1 and has a length sufficient to accommodate the guide block 43, and the inner surface of the jaws of the T-slot 42 is axially aligned with the guide 32' with precision. Machined high and parallel.

A guide block 43 having an I-shaped cross section and having the same length as the T groove 42 is fitted across the T grooves 41 and 42, but the sections of the guide block 43 that contact the webs slide into the T grooves 41 and 42; The slide valve 3 is located between the surfaces 44 and 45 of the T grooves 41 and 42 that correspond to the back side of the jaws.
2 can move in the axial direction, the T-slot 4
The gap between the inner surface of the jaws 1 and 42 is made as small as possible.

The guide block 43 is guided in its axial movement by a slide valve guide 46 fixed to the discharge side end wall, and the slide valve 32 has a T-slot 41.
A blind cover 47 that reduces gas leakage is fixed to the.

The slide valve 32 is moved in the axial direction via the piston 28 and the piston rod 31 by the pressure oil flowing in and out from the pressure oil inlets and outlets 34 and 35. At this time, the guide 32' and the guide block 43
It cannot move upwards beyond 2' and cannot rotate.

The guide block 43 prevents the slide valve 32 from moving upward and coming into contact with the outer peripheries of the male rotor 4 and female rotor 5, and the guide block 43 prevents the slide valve 32 from rotating. Therefore, the clearance between the slide valve 32 and the male rotor 4 and female rotor 5 is ensured.
The outer peripheries of the male rotor 4 and female rotor 5 are not worn, and efficiency does not decrease. In the conventional design disclosed in Beta Utility Model Publication No. 55-140781, parallel grooves are provided on both sides of the slide valve, and the indexing (circumference is divided into two) accuracy must be accurate. The drilling of the holes in the casing into which the pins to be inserted are driven is difficult, and it is especially difficult to drill holes in accurate positions. It is also possible to insert the slide valve 32 into the block and process the guide block 43 while it is locked.In this state, the surfaces 44 and 45 of the guide block 43 can be ground to perform the current or selective fitting, making it extremely easy to process. It's advantageous. Of course, T-slots 41 and 4 are cut as in normal machining.
2, the slide valve 32 and the rotor casing may be machined, finished, assembled and measured, and the surfaces 44 and 45 of the guide block 43 may be ground in the same way for the current or selective fitting. .

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of this invention, Fig. 2 is a sectional view taken along line AA in Fig. 1, and Fig. 3 is a sectional view taken along line B-- in Fig. 1.
B sectional view, FIG. 4, a partially enlarged view of FIG. 3, and FIG. 5 are explanatory views regarding the clearance of the slide valve. 1... Rotor casing, 4... Male rotor, 5
...Female rotor, 32...Slide valve, 32'
... Guide, 41, 42 ... T groove, 43 ... Guide block, 44, 45 ... Surface, 46 ... Slide valve guide, 47 ... Blind cover.

Claims (1)

[Scope of utility model registration request] Two cylindrical bores are provided in the casing parallel to each other and overlapped with each other so that the distance between the axes is smaller than the diameter thereof, each of which is supported rotatably about the bore axis. The casing has a suction side end wall and a discharge side end wall perpendicular to the bore axis at both ends of the bore, and the suction side end wall and the discharge side end wall have a A screw compressor comprising an end wall suction port and an end wall discharge port, bearings for supporting the male and female rotors on the suction side and the discharge side, respectively, and a slide valve for controlling capacity on a part of the casing wall. , a T-groove is provided in the axial direction in the guide of the slide valve and the rotor casing into which the slide valve is fitted, on a plane that is substantially perpendicular to the plane that includes both the bore axes and includes the center of the slide valve, and the T-groove has a cross section I. A screw compressor characterized by an inset guide block.