JPS60138295A - Screw compressor - Google Patents

Abstract

PURPOSE:To enable the capacity of a slide valve to be 0-100% adjusted without causing any necessity for changing a stroke of the slide valve, by providing grooves, whose one end is opened to a suction side end face of the slide valve, on a slide surface of the slide valve in its opposite side to a rotor chamber. CONSTITUTION:A pair of grooves 16, one end of which is opened to a suction side end face 15, are provided to be cut on a slide surface 14 of a slide valve 9 in its opposite side to a rotor chamber. If the slide valve is moved to a full stroke, gas in the side of a delivery port 7 is allowed to flow into a bypass passage 11 in a suction port 6 through the groove 16, decreasing the capacity. While the groove 16 is formed in a trigonal pyramid shape gradually decreasing its capacity in accordance with a position from the side of the suction port 6 toward the side of the delivery port 7. In this way, the capacity corresponding to a protrusive distance of the groove 16 to the side of the delivery port can bypass the valve.

Description

[Detailed description of the invention] (Industrial application field) The present invention is a screwdriver having a slide valve for adjusting capacity.

The present invention relates to means for improving capacity control in the low capacity range of a compressor.

(Prior Art) As shown in FIGS. 1 and 2, the screw compressor has the following features:
A pair of female and male Scrico rotors (hereinafter referred to as rotors) 1 and 2 that rotate while meshing with each other is provided in the rotor chamber 4 of the casing 3. It communicates with the suction port 6 through the suction side opening 5 which is formed by partially cutting out the groove so as to correspond to the position of the groove.
Further, on the end face on the discharge side, although the shape of the opening 1 is different, it communicates with the discharge lower in the same manner. Furthermore, a cylindrical cavity is formed in the lower part of the rotor chamber 4, partially overlapping with the rotor chamber 4 and communicating with the suction port 6. A slide valve (length Ll) 9 having a curved surface 8 with a chevron-shaped arcuate cross section is slidably inserted in the rotor axial direction, and a slide valve (J
The forward limit position is determined by a fixed valve 1o.

Then, this screw compressor traps and compresses the gas sucked in through the suction port 6 in the rotor chamber 4 between the rotors 1 and 2 and the casing 3, and then discharges the gas to the discharge lower. On the other hand, when adjusting the capacity, a part of the gas trapped in the rotor chamber 4 is bypassed through the passage 11 to the suction side. That is, by moving the slide valve 9 forward and backward in the rotor axial direction, the closing start position by the rotor 1.2 is adjusted 4-
Capacity can be controlled by filtering.

Incidentally, the range in which the capacity can be adjusted only by this type of slide valve is 100 to 15%, and special work is required for low capacity adjustment below 15%. Specifically, as shown in Fig. 3, a so-called bypass line 13 is installed to return part of the gas discharged from the discharge lower to the suction side piping 12, and as shown in Fig. 4, the stroke of the slide valve (lateral It is necessary to extend the stroke of the slide valve until the adjustment capacity becomes zero to show the relationship between the adjustment capacity (vertical axis) and the adjustment capacity (vertical axis).

However, in the former case, it is necessary to install an extra bypass line, and in the latter case, the amount of movement of the slide valve increases and the compressor body becomes larger than the conventional one. , the length of the cylinder for driving the slide valve becomes long, and in both cases, there is a problem that an increase in cost is unavoidable and it is not practical.

(Purpose of the Invention) Therefore, the present invention (J) In view of the above-mentioned problems, the stator of the slide valve is changed from the conventional one by adding four dimensions to the conventional slide valve. 100% to 0%
We offer a screw compressor that allows capacity adjustment over the entire range of (
)

(Structure of the Invention) The present invention is characterized by a pair of male and female rotors meshing with each other, a rotor chamber surrounding the rotor, and a curved surface having a chevron-shaped arcuate cross section forming a part of the rotor chamber wall surface. - a screw compressor equipped with a capacity adjusting slide valve slidably provided in the rotor axial direction, one end of which is opened at the suction side end surface of the slide valve on the sliding surface of the slide valve on the side opposite to the rotor chamber; A groove is set up (located at the point J).

(Example) The present invention will be explained in detail below based on the illustrated embodiments.

The structure of the compressor main body is the same as that of the Scrico compressor except for the slide valve. On the sliding surface on the side opposite to the rotor chamber, a pair of grooves 16 are cut into the sliding surface 14, one end of which opens on the suction side end surface I5.The grooves 16 have a triangular pyramid shape with the opening side as the bottom surface. The length y is slightly longer than the overlapping length X of the slide valve guide 17 and the slide valve when the slide valve is fully stroked, as shown by the two-dot chain line in FIG.

In the Scrico compressor of the present invention configured as described below, when the slide valve 9 is moved by a full stroke I-+, the gas on the discharge lower side passes through the groove 16 and flows into the suction port 6. It flows into the bypass passage 11 for further volume adjustment. In particular, by forming the groove 16 into a triangular pyramid shape whose capacity gradually decreases from the suction port 6 side to the discharge lower side, the capacity corresponding to the amount of protrusion of the groove 16 toward the discharge port side 7 is bypassed. This makes it easy to adjust low capacity.

The relationship between the displacement and capacity of the slide valve 9 in the above embodiment is shown in FIG. 4 by a two-dot chain line.

4- Note that the groove I6 is not limited to the above embodiment, and the number of surfaces may be one or three or more, and
The groove shape is not limited to a regular pyramid, but can also be a square groove, a semicircular groove, etc., and by changing the length y or groove width for each groove, in other words, it can be connected to the lower discharge side according to the stroke of the slide valve. More delicate capacity adjustment is also possible by changing the number of communicating grooves 16. However, if the length y of the groove 16 is too long, it will bypass quickly and cause a power loss, so it is necessary to take this into consideration along with the groove shape when setting.

By the way, the slide valve is usually prevented from rotating by engaging an alignment frame installed in the casing of the compressor. Ill 6a with a concave cross section in the center of the bottom surface like a machine
The alignment frame 22 having the casing 2I penetrating the groove 16a may be slidably engaged with the groove 16a by using the slide valve 9a having a groove 16a formed therein. Furthermore, in this embodiment, as shown in the figure, the alignment frame 22 can be adjusted by moving the protruding finger into the casing 21 by raising and lowering the adjusting bolt 23 provided behind the alignment frame 22. This is provided so that the opening area of the IJ groove +6a can be adjusted as appropriate.

In FIG. 6, substantially the same parts as in FIG. 1 are given the same numbers.

Therefore, in the screw compressor using the slide valve 9 shown in FIG. 5, once the groove 16 is machined, the fourth
The capacitance characteristics shown in the figure are not only determined uniquely and cannot be changed, but also difficult to predict.However, if the slide valve 9a formed with the groove 16a as in this embodiment is used, it can be used commonly for alignment. , and the titer properties can also be adjusted appropriately as shown in FIG. 1O. Zunawaji, in Figure 10, A +
The a-+elli line and the A-a→h curve are the same as those shown in FIG. 4, and the former (A-1-a-1-e) is for the conventional slide valve 9 (without iM).

The latter (A->a-*h) shows the capacity characteristic curve when the grooved slide valve 9 shown in FIG. 5 is used.

The A-+a-+b-sr curve, the A→a-c-+g curve, and the A→a-+d-1-11 curve are shown in the screw compressor shown in FIG. At each stage when the opening area is expanded by
7, the position of the curve decreases as the area increases.

Furthermore, if the depression of a→b, a=c, or a→d becomes a problem as described above, instead of the groove 16a shown in FIG. 7, a slide valve 9b shown in FIG. 8 may be used. A groove +6b formed by narrowing the groove rj+ at the tip, or a groove 16 narrowed in the depth direction as in the slide valve 9C shown in Fig. 9.
You may also use chino that forms c. The capacitance characteristic curve in this case becomes a-+-i->f curve, a-j-g curve as the opening area is increased by the alignment frame 22 in the same manner as described above.
The curve changes to 84-h curve.

(Effects of the Invention) As detailed above, according to the present invention, the stroke of the slide valve can be increased by simply adding a groove in the sliding surface of the slide valve with one end opening on the suction side. Capacity adjustment over the entire range of 100% to 0% is possible without changing from the conventional method, and can be performed extremely easily and at low cost. Furthermore, even an existing screw pressure compressor can be improved by simply cutting a groove in the slide valve, and the effects produced by this can greatly contribute to the industrial world.

[Brief explanation of the drawings] Fig. 1 is a front cross-sectional view of a conventional screw compressor with a slide valve, Fig. 2 is a cross-sectional view taken along line I-1 in Fig. 1, and Fig. 3 is a cross-sectional view of a conventional screw compressor with a slide valve. An explanatory diagram, FIG. 4 is an explanatory diagram of the relationship between the slide valve stroke and adjustment capacity, and FIG. 5 is a perspective view of the slide valve in the screw compressor according to the present invention.
6 is a sectional view of a screw compressor showing another embodiment of the present invention, FIG. 7 is a bottom view of the slide valve in FIG. 6, and FIG. 8 is a sectional view of a screw compressor showing another embodiment of the present invention. FIG. 9 is a bottom view and a vertical sectional view showing another embodiment of the slide valve according to the present invention, and FIG. 1O is an explanatory diagram of the relationship between the slide valve stroke and the adjustment capacity. Patent applicant: Kobe Steel, Ltd. Representative Patent attorney: Aohaku Ao and 2 others 8-

Claims (1)

[Claims] (1) A pair of male and female rotors meshing with each other, a rotor chamber surrounding the rotors, and a curved surface with a chevron-shaped arc shape in cross section forming a part of the wall surface of the rotor chamber, and the rotor is slidably arranged in the axial direction of the rotor. ) A screw compressor equipped with a slide valve for adjusting the capacity of the slide valve, characterized in that a groove having one end open on the suction side end surface of the slide valve is provided on the sliding surface of the slide valve on the side opposite to the rotor chamber. Screw compressor.