JP2012229640A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw compressor capable of reducing leakage loss while suppressing increase in discharge loss.SOLUTION: This screw compressor 100 includes: a screw rotor 4 on whose outer peripheral surface a plurality of lines of screw grooves 10 are formed; a gate rotor 7 on whose outer periphery a plurality of gate rotor teeth meshed with the screw grooves 10 are formed; and a casing 1 in which an accommodation part 1c rotatably accommodating the screw rotor 4 and a discharge port 15 opening to the accommodation part 1c are formed. A gate rotor opening 1d for inserting a gate rotor 7 into the accommodation part 1c is formed in the casing 1. A distance between the discharge port 15 and the gate rotor opening 1d at a discharge side is relatively longer than that at a suction side along a rotary shaft direction of the screw rotor 4.

Description

  The present invention relates to a screw compressor used in a refrigeration cycle for refrigeration and air conditioning.

  As a conventional screw compressor for improving the performance of the screw compressor, for example, a screw compressor described in Patent Document 1 has been proposed. The conventional screw compressor described in Patent Document 1 forms a compression chamber by combining a screw rotor having a plurality of helical screw grooves and a gate rotor having a plurality of teeth in a casing. Further, the conventional screw compressor described in Patent Document 1 includes a columnar slide valve that slides in the direction of the rotation axis of the screw rotor. The opening of the bypass port and the opening of the discharge port can be adjusted by sliding the slide valve.

  A discharge port of a conventional screw compressor described in Patent Literature 1 is formed by a wall surface of an opening provided in a casing and a discharge-side end surface of a slide valve, and a variable port whose area is changed by movement of the slide valve, and a variable port And a fixed port provided between the lower portion of the upper portion and an opening portion into which the gate rotor teeth are inserted (hereinafter referred to as an opening portion for the gate rotor). Furthermore, the conventional screw compressor described in Patent Document 1 is provided with a parallelogram-shaped subport on the suction side of the fixed port in order to increase the discharge area during full load operation. In other words, the sub port communicates with the compression chamber and the variable port during full load operation when the slide valve slides to the suction side, and the sub port is the side portion of the slide valve during partial load operation when the slide valve slides to the discharge side. And is separated from the variable port. That is, in the conventional screw compressor described in Patent Document 1, during the partial load operation, the slide valve slides from the suction side to the discharge side, and the bypass port is opened, thereby delaying the compression start timing. Further, in the conventional screw compressor described in Patent Document 1, since the subport is in a fixed position on the suction side, the discharge start timing does not change during partial load operation, and the internal volume ratio becomes small. Is preventing.

JP 2005-54719 A

  In the screw compressor, the opposed area between the spiral screw groove that moves relatively from the suction side to the discharge side of the casing as the screw rotor rotates and the discharge port formed in the casing is a substantial discharge area. In the conventional screw compressor described in Patent Document 1, in order to secure the discharge area at the end of the discharge stroke, the casing is cut out to the discharge side corner of the discharge port to form a fixed port. Thereby, the conventional screw compressor described in Patent Document 1 suppresses an increase in discharge loss. Here, in the conventional screw compressor described in Patent Document 1, the wall surface of the fixed port on the gate rotor opening side and the fixed port side wall surface of the gate rotor opening along the rotation axis of the screw rotor. It has a parallel shape. That is, the distance between the wall surface on the gate rotor opening side of the discharge port and the discharge port side wall surface of the gate rotor opening is larger than the range in which the fixed port is provided in the range where the fixed port is provided. It is getting shorter.

  Here, a high-pressure screw groove and a low-pressure gate rotor support chamber are defined between the wall surface on the gate rotor opening side of the discharge port and the discharge port side wall surface of the gate rotor opening. It also functions as a sealing part. For this reason, in the conventional screw compressor described in Patent Document 1, the distance between the wall surface on the gate rotor opening side of the discharge port and the discharge port side wall surface of the gate rotor opening portion is short in the formation range of the fixed port. Therefore, there is a problem that high-pressure refrigerant gas leaks through the portion, and leakage loss increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a screw compressor capable of reducing leakage loss while suppressing increase in discharge loss.

  A screw compressor according to the present invention includes a screw rotor having a plurality of screw grooves formed on the outer peripheral surface, a gate rotor having a plurality of teeth meshed with the screw grooves formed on the outer peripheral portion, a housing portion, A discharge port that opens in the housing portion, and a casing that rotatably houses the screw rotor in the housing portion, and the casing includes a gate rotor opening that opens in the housing portion, The outer periphery of the gate rotor is inserted into the accommodating portion through the gate rotor opening, the screw groove and the teeth are meshed, and the screw rotor rotates, whereby the peripheral wall of the accommodating portion, Refrigerant was sucked into the compression chamber, which is a space surrounded by the screw rotor and the gate rotor, and compressed from the discharge port. In the screw compressor that discharges the medium, a distance between the discharge port and the gate rotor opening is relatively longer on the discharge side than on the suction side along the rotation axis direction of the screw rotor. Is.

  Discharge loss and leakage loss are in a trade-off relationship. In the present invention, the distance between the discharge port and the gate rotor opening is relatively small in the first half of the discharge stroke in which the discharge area (opposite region between the screw groove and the variable port) is small in the overall discharge stroke. doing. Thereby, the discharge overshoot pressure can be reduced by increasing the discharge area in the first half of the discharge stroke. Further, in the present invention, the middle of the discharge stroke in which the discharge area (opposite area between the screw groove and the variable port) becomes larger in the discharge stroke in general, since the influence on the discharge loss is small even if the discharge area is reduced. The distance between the discharge port and the gate rotor opening is relatively long. As a result, the frictional resistance in the middle of the discharge stroke and the leakage path can be increased, and leakage loss from high pressure to low pressure can be reduced. In the present invention, the end of the discharge stroke in which the discharge area (opposite area between the screw groove and the variable port) is reduced again in the overall discharge stroke is also relative to the distance between the discharge port and the gate rotor opening. Is long. As in the middle of the discharge stroke, the frictional resistance of the leakage path is increased to reduce leakage loss from high pressure to low pressure. This is because, at the end of the discharge stroke, since the volume change rate of the compression chamber (that is, the refrigerant outflow amount) is small, the influence on the discharge loss is small even if the discharge area is reduced.

  As described above, according to the present invention, the discharge port is formed in a shape that takes into account the change in the discharge area and the volume during the discharge stroke, so that it is possible to reduce leakage loss while suppressing increase in discharge loss. A screw compressor is obtained.

It is a schematic sectional drawing (plane sectional drawing) of screw compressor 100 concerning Embodiment 1 of the present invention. It is AA sectional drawing of FIG. It is a perspective view which shows the discharge port 15 vicinity (accommodating part) of the screw compressor 100 which concerns on Embodiment 1 of this invention. It is explanatory drawing of the discharge port 15 vicinity of the screw compressor 100 which concerns on Embodiment 1 of this invention. It is an expanded view of the accommodating part 1c inner surface and screw rotor 4 outer peripheral surface of the screw compressor 100 which concern on Embodiment 1 of this invention. It is the perspective view which looked at the discharge port 15 of the screw compressor 100 which concerns on Embodiment 1 of this invention from the accommodating part 1c. It is explanatory drawing which shows the compression principle of the screw compressor 100 which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the rotation angle of the screw rotor 4 and the volume of the compression chamber 11 in the screw compressor 100 which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed typically the refrigerant | coolant leak path | route from the clearance gap formed between the screw rotor 4 and the accommodating part 1c. It is explanatory drawing for demonstrating the relationship between the screw rotation angle and discharge area in the screw compressor 100 which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the screw rotation angle and discharge area in the screw compressor 100 which concerns on Embodiment 1 of this invention. It is an expanded view of the accommodating wall 1c inner surface and screw rotor 4 outer peripheral surface of the screw compressor 100 which concerns on Embodiment 2 of this invention. It is the perspective view which looked at the discharge port 15 of the screw compressor 100 which concerns on Embodiment 2 of this invention from the accommodating part 1c. It is an expanded view of the accommodating wall 1c inner surface and screw rotor 4 outer peripheral surface of the screw compressor 100 which concerns on Embodiment 3 of this invention. It is the perspective view which looked at the discharge port 15 of the screw compressor 100 which concerns on Embodiment 3 of this invention from the accommodating part 1c. It is an expanded view of the accommodating part 1c inner wall surface and screw rotor 4 outer peripheral surface of the screw compressor 100 which concerns on Embodiment 4 of this invention. It is the perspective view which looked at the discharge port 15 of the screw compressor 100 which concerns on Embodiment 4 of this invention from the accommodating part 1c. It is an expanded view of the accommodating part 1c inner surface and screw rotor 4 outer peripheral surface of the screw compressor 100 which concern on Embodiment 5 of this invention. It is the perspective view which looked at the discharge port 15 of the screw compressor 100 which concerns on Embodiment 5 of this invention from the accommodating part 1c. It is an expanded view of the accommodating wall 1c inner surface and screw rotor 4 outer peripheral surface of the screw compressor 100 which concerns on Embodiment 6 of this invention. It is the perspective view which looked at the discharge port 15 of the screw compressor 100 which concerns on Embodiment 6 of this invention from the accommodating part 1c.

Embodiment 1 FIG.
Hereinafter, the screw compressor 100 according to Embodiment 1 of the present invention will be described.
1 is a schematic cross-sectional view (planar cross-sectional view) of a screw compressor according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. In FIGS. 1 and 2 and the drawings shown below, the same reference numerals denote the same or corresponding parts, which are common throughout the entire specification. Furthermore, the form of the constituent elements appearing in the whole specification is merely an example, and is not limited to these descriptions.

The screw compressor 100 includes a casing 1, a screw rotor 4, a gate rotor 7, an electric motor 8 that rotationally drives the screw rotor 4, a slide valve 12, and the like.
The casing 1 accommodates a screw rotor 4, a gate rotor 7, an electric motor 8 that rotationally drives the screw rotor 4, a slide valve 12, and the like, and a substantially cylindrical space in which the screw rotor 4 is accommodated. The accommodating part 1c which is is formed. Further, the casing 1 is formed with a discharge port 15 that opens to the accommodating portion 1c. Details of the discharge port 15 will be described later.

  A substantially cylindrical screw rotor 4 is accommodated in the accommodating portion 1c. A plurality of screw grooves 10 are spirally formed on the outer peripheral surface of the screw rotor 4. Further, the screw rotor 4 is provided with a screw shaft 9 at the center axis (rotary shaft) thereof. The screw shaft 9 is rotatably supported by a high pressure side bearing 2 and a low pressure side bearing 3 provided in the casing 1. An electric motor 8 whose frequency is controlled by an inverter (not shown), for example, is connected to the end of the screw shaft 9 on the low-pressure side bearing 3 side.

  The casing 1 is formed with gate rotor support chambers 6 for accommodating a substantially disc-shaped gate rotor 7 on the left and right sides of the accommodating portion 1c (that is, the screw rotor 4). The gate rotor 7 accommodated in the gate rotor support chamber 6 is provided in the gate rotor support 5 accommodated in the gate rotor support chamber 6. The gate rotor support 5 is disposed so that the center axis (rotation axis) thereof is substantially perpendicular to the rotation axis of the screw rotor 4 (that is, the screw shaft 9), and is disposed at the upper and lower portions of the gate rotor support chamber 6. The bearing 5a is rotatably supported. As shown in FIG. 2, the gate rotor 7 and the gate rotor support 5 accommodated in the gate rotor support chamber 6 formed on the left side of the accommodating portion 1c (that is, the screw rotor 4), and the accommodating portion 1c (that is, the screw) The gate rotor 7 and the gate rotor support 5 housed in the gate rotor support chamber 6 formed on the right side of the rotor 4) are rotated by 180 ° around the rotation axis of the screw rotor 4 (that is, the screw shaft 9). It has been arranged.

  The gate rotor 7 forms a compression chamber 11 together with the accommodating portion 1c and the screw rotor 4, and a plurality of gate rotor teeth 7a that are engaged with the screw grooves 10 are formed on the outer peripheral portion thereof. More specifically, the casing 1 is formed with a gate rotor opening 1d that allows the housing 1c and the gate rotor support chamber 6 to communicate with each other (open to the housing 1c). The outer periphery of the gate rotor 7 is inserted into the gate rotor opening 1d. That is, the gate rotor 7 is inserted into the accommodating portion 1 c through the gate rotor opening 1 d, and the gate rotor teeth 7 a of the gate rotor 7 are engaged with the screw grooves 10 of the screw rotor 4. As a result, the space surrounded by the gate rotor 7, the inner wall of the accommodating portion 1 c and the screw rotor 4 (in other words, the screw rotor 10 partitioned by the gate rotor teeth 7 a of the gate rotor 7 and the accommodating portion 1 c) is connected to the compression chamber 11. Become.

Further, the casing 1 is formed with two slide holes 14 for accommodating the slide valve 12 so as to be movable in the direction of the rotation axis of the screw rotor 4 (that is, the screw shaft 9) on the outer peripheral side of the accommodating portion 1c. ing. Specifically, the two slide holes 14 are formed in a substantially cylindrical shape, and have a shape in which a part of the side surface portion communicates with the accommodating portion 1c. These slide holes 14 are arranged to be rotated 180 ° around the rotation axis of the screw rotor 4 (that is, the screw shaft 9).
Similar to the slide hole 14, the slide valve 12 provided in the slide hole 14 is formed in a substantially cylindrical shape. And these slide valves 12 are formed in the shape where the outer peripheral surface facing the accommodating part 1c followed the inner peripheral wall of the accommodating part 1c. A linear motion actuator (not shown) is connected to the slide valve 12, and the linear motion actuator is driven to move in the slide hole 14 in the direction of the rotation axis of the screw rotor 4 (that is, the screw shaft 9). .

(Detailed configuration near the discharge port 15)
Next, a detailed configuration near the discharge port 15 of the screw compressor 100 according to Embodiment 1 will be described.
FIG. 3 is a perspective view showing the vicinity (container) of discharge port 15 of screw compressor 100 according to Embodiment 1 of the present invention. FIG. 4 is an explanatory view of the vicinity of the discharge port 15 of the screw compressor 100. FIG. 5 is a development view of the inner wall surface of the accommodating portion 1 c and the outer peripheral surface of the screw rotor 4 of the screw compressor 100. FIG. 6 is a perspective view of the discharge port 15 of the screw compressor 100 as viewed from the inside of the accommodating portion 1c. FIG. 3 is a perspective view seen from the white arrow side of FIG. 3A shows a state where the slide valve 12 is moved to the discharge side, and FIG. 3B shows a state where the slide valve 12 is moved to the suction side.

  As shown in FIG. 3, the slide valve 12 is movably fitted in a slide hole 14 (not shown) parallel to the screw shaft 9, and the discharge start timing is changed by changing the position of the discharge side end face 12 d of the slide valve 12. Adjust. That is, in the screw compressor 100 according to the first embodiment in which the slide valve 12 is provided, the discharge port 15 has an opening formed in the casing 1 (more specifically, an opening that opens in the housing portion 1c). And the discharge-side end surface 12d of the slide valve 12 are surrounded.

  Here, in the following description, the discharge port 15 is defined as shown in FIG. That is, a region of the discharge port 15 that opens to the same screw rotor central angle range as the slide valve 12 is defined as a variable port 15a (thick hatched portion in the figure). Further, in the discharge port 15, a region other than the variable port 15 a is set as a fixed port 15 b (a thin hatched portion in the figure). Further, a part of the peripheral wall of the discharge port 15 and a part of the peripheral wall of the gate rotor opening 1d are defined as shown in FIG. That is, as shown in FIG. 3, the gate rotor opening 1 d is formed below the discharge port 15 (that is, the gate rotor opening 1 d is above the discharge port 15 on the back side of FIG. 3. Formed). Here, a wall surface on the discharge port 15 side of the gate rotor opening 1d formed along the screw shaft 9 is defined as a casing lip surface 1a. The wall surface on the gate rotor opening 1d side of the fixed port 15b is defined as a discharge port wall surface 1b.

  As shown in FIGS. 5 and 6, in the first embodiment, the distance from the casing lip surface 1a of the gate rotor opening 1d to the discharge port wall surface 1b of the fixed port 15b is varied in the direction of the screw shaft 9. ing. That is, on the suction side of the fixed port 15b, the distance from the casing lip surface 1a of the gate rotor opening 1d to the discharge port wall surface 1b of the fixed port 15b is shortened so that the opening area is increased. The distance from the casing lip surface 1a of the gate rotor opening 1d to the discharge port wall surface 1b of the fixed port 15b is gradually increased so that the opening area decreases toward the discharge side. Further, in the first embodiment, in order to adjust the discharge area at the end of the discharge stroke, an opening on the screw groove 10 side (that is, in the accommodating portion 1c) is formed at the discharge side corner of the fixed port 15b (discharge port wall surface 1b). A notch 15c having a rectangular shape is formed. Further, the notch 15c is opened on the screw groove 10 side (that is, in the accommodating portion 1c), the discharge port wall surface 1b of the fixed port 15b, and the outer peripheral surface of the accommodating portion 1c. Furthermore, the suction side wall surface of the discharge port 15 (the variable port 15a and the fixed port 15b) has a shape along the inclination of the screw groove 10 at the start of discharge. Here, the notch 15c corresponds to the discharge area adjusting section in the present invention.

(Description of operation)
Next, the operation of the screw compressor 100 configured as described above will be described.
FIG. 7 is an explanatory diagram illustrating the compression principle of the screw compressor 100 according to Embodiment 1 of the present invention. FIG. 8 is a characteristic diagram showing the relationship between the rotation angle of the screw rotor 4 and the volume of the compression chamber 11 in the screw compressor 100.

  As shown in FIG. 7, when the screw rotor 4 is rotated by the electric motor 8 via the screw shaft 9, the suction stroke, the compression stroke, and the discharge stroke are repeated. FIG. 7A shows the state of the compression chamber 11 during the suction stroke. When the screw rotor 4 is driven by the electric motor 8 and rotated in the direction of the solid arrow, the lower gate rotor 7 shown in FIG. 7 rotates in the direction of the white arrow as the screw rotor 4 rotates. Further, the upper gate rotor 7 shown in FIG. 7 rotates in the opposite direction to the lower gate rotor 7 as indicated by a hollow arrow. In the suction stroke, the compression chamber 11 has the largest volume, and the compression chamber 11 is filled with a low-pressure refrigerant gas in a state of communicating with the low-pressure space.

When the screw rotor 4 further rotates, the two gate rotor teeth 7a sequentially rotate toward the discharge port 15 as shown in FIG. 7B, whereby the refrigerant gas in the compression chamber 11 is moved into the compression chamber. 11, the volume (volume) of the compression chamber 11 is reduced, and the refrigerant gas is compressed.
When the screw rotor 4 continues to rotate, the compression chamber 11 communicates with the discharge port 15 as shown in FIG. As a result, the compressed high-pressure refrigerant gas is discharged from the discharge port 15 to the outside. Then, the same compression is performed again on the back surface of the screw rotor 4.
The open screw groove 10 not covered by the casing 1 (that is, the inner wall surface of the housing portion 1c) communicates with the gate rotor support chamber 6 in which the gate rotor 7 and the gate rotor support 5 on the opposite side are housed. Inhalation pressure atmosphere.

  In the screw compressor 100 according to the first embodiment, the compression operation from the start of compression to the completion of discharge described above is performed when the rotation angle of the screw rotor 4 (hereinafter also referred to as screw rotation angle) is 0 ° to 180 °. The volume change of the compression chamber 11 with respect to the screw rotation angle is as shown in FIG.

  In order to perform the above-described compression operation, the screw rotor 4 and the gate rotor 7 need to be moved relative to each other, and the screw rotor 4 and the casing 1 need to be moved relative to each other. For this reason, it is necessary to form a gap between the screw rotor 4 and the gate rotor 7 and between the screw rotor 4 and the casing 1, and the compression chamber 11 is not completely sealed. For this reason, the screw compressor 100 according to the first embodiment prevents leakage of compressed refrigerant gas from the high pressure compression chamber 11 to the low pressure compression chamber 11 and the gate rotor support chamber 6 through the gap. Refrigerant leakage from the gap is reduced by actively injecting oil (lubricating liquid) such as refrigeration oil into the compression chamber 11.

  FIG. 9 is an explanatory view schematically showing a refrigerant leakage path from a gap formed between the screw rotor 4 and the casing 1 (accommodating portion 1c). In FIG. 9, an arrow (1) is a refrigerant leakage path between adjacent compression chambers 11. In the screw compressor 100 according to the first embodiment, refrigerant leakage between the compression chambers 11 is suppressed by forming a plurality of compression chambers 11 to reduce the leakage differential pressure. Arrow (2) is a refrigerant leakage path from the compression chamber 11 to the suction pressure space in which the high-pressure side bearing 2 is accommodated. In the screw compressor 100 according to the first embodiment, by providing an orthogonal labyrinth seal (not shown) at the end of the screw rotor 4, refrigerant leakage from the path is suppressed. An arrow (3) is a refrigerant leakage path from the fixed port 15b to the gate rotor support chamber 6. In the screw compressor 100 according to the first embodiment, the distance from the casing lip surface 1a serving as the refrigerant leakage path to the discharge port wall surface 1b is partially increased to increase the frictional resistance of the flow path, thereby Is suppressed.

  Here, regarding the shape of the discharge port wall surface 1b, if the leakage flow path length of the arrow (3) is increased as described above, the discharge area is reduced, and there is a concern that the discharge loss increases. However, in the screw compressor 100 according to the first embodiment, the discharge is performed so that the distance from the casing lip surface 1a of the gate rotor opening 1d to the discharge port wall surface 1b of the fixed port 15b is formed as described above. A port wall surface 1b is formed. That is, in the screw compressor 100 according to the first embodiment, the shape of the discharge port wall surface 1b is made to close the region where the influence on the discharge loss is small (the length of the leakage flow path becomes long). Hereinafter, the details of the operation during the discharge stroke of the screw compressor 100 according to the first embodiment will be described with reference to FIGS. 10 and 11. In addition, the substantial discharge area of a screw compressor becomes an opposing area | region of a discharge port and a screw groove.

FIG. 10 is an explanatory diagram for explaining the relationship between the screw rotation angle and the discharge area in the screw compressor 100 according to Embodiment 1 of the present invention. FIG. 11 is a characteristic diagram showing the relationship between the screw rotation angle and the discharge area in the screw compressor 100.
In addition, FIG. 10 has shown the discharge area area | region on the expanded view of the screw rotor 4 outer peripheral surface. More specifically, FIG. 10A shows a discharge area around the screw rotation angle of 80 ° (opposite region C between the screw groove 10 and the discharge port 15 represented by a horizontal line portion) and a discharge around the screw rotation angle of 140 °. The area (the opposed region D between the screw groove 10 and the discharge port 15 represented by the hatched portion) is shown. FIG. 10B shows a discharge area around the screw rotation angle of 90 ° (opposite area C between the screw groove 10 and the discharge port 15 represented by a horizontal line portion) and a discharge area around the screw rotation angle of 150 ° (hatched portion). 2 shows a facing region D) between the screw groove 10 and the discharge port 15. FIG. 10C shows a discharge area (a confronting region C between the screw groove 10 and the discharge port 15 represented by a horizontal line portion) near a screw rotation angle of 130 °.
Moreover, as shown in FIG. 11, the discharge area of the screw compressor 100 according to the first embodiment is maximized around a screw rotation angle of 120 ° and is expressed by a convex parabola.

  As can be seen from FIGS. 10 and 11, immediately after the compression chamber 11 communicates with the discharge port 15, the discharge area is small and the discharge flow rate is increased. The dynamic pressure loss increases in proportion to the square of the discharge flow rate. However, the screw compressor 100 according to the first embodiment attempts to reduce the discharge loss by enlarging the discharge area immediately after the start of discharge by taking a large opening on the suction side of the fixed port 15b. On the other hand, since the discharge area increases near the screw rotation angle of 120 °, the contribution of the discharge area of the fixed port 15b portion decreases. For this reason, as described above, the opening is made small at the center of the fixed port 15b to reduce the leakage of the route indicated by the arrow (3) in FIG.

  After the screw rotation angle of 120 °, the discharge area decreases with the rotational movement of the screw groove 10. When the screw rotation angle is near 150 °, only the facing portion between the screw groove 10 and the fixed port 15b becomes the discharge area. However, the volume change becomes small after the screw rotation angle of around 130 ° enclosed by the broken line in FIG. 8, and the volume change becomes 1% or less of the suction volume when the screw rotation angle reaches 150 °. Since the power required for the discharge stroke is represented by the integration of the volume change and the pressure in the compression chamber, even if the discharge area is reduced and the pressure rises at the end of the discharge stroke, the volume change is small and the loss itself becomes small. Further, after the screw rotation angle of 140 °, the adjacent screw grooves 10 communicate with each other through the discharge port 15 as shown in FIGS. 10A and 10B, so that the pressure rise does not become excessive. Accordingly, the discharge-side corner of the fixed port 15b through which the screw groove 10 at the end of the discharge stroke passes is provided with a small slit-shaped notch 15c as described above to reduce the leakage of the arrow (3) in FIG. ing.

  As described above, in the screw compressor 100 according to the first embodiment, the shape of the fixed port 15b takes into consideration the discharge area and volume that change according to the screw rotation angle, and the leakage loss is reduced within a range that does not increase the discharge loss. Since it has a shape that can be made, it can be a highly efficient screw compressor with low overall loss.

Embodiment 2. FIG.
In the first embodiment, as a discharge area adjusting portion, a notch 15c having a rectangular opening shape on the screw groove 10 side (that is, in the accommodating portion 1c) is formed at the discharge side corner of the fixed port 15b (discharge port wall surface 1b). Formed. Not only this but the discharge area adjustment part formed in the discharge side corner part of the fixed port 15b (discharge port wall surface 1b) is good also as following shapes. Items that are not particularly described in the second embodiment are the same as those in the first embodiment.

FIG. 12 is a development view of the inner wall surface of the accommodating portion 1c and the outer peripheral surface of the screw rotor 4 of the screw compressor 100 according to Embodiment 2 of the present invention. FIG. 13 is a perspective view of the discharge port 15 of the screw compressor 100 as viewed from the inside of the accommodating portion 1c.
As shown in FIGS. 12 and 13, in the screw compressor 100 according to the second embodiment, a notch 15d is formed at the discharge-side corner of the fixed port 15b (discharge port wall surface 1b) as a discharge area adjusting unit. ing. The notch 15d is formed in a right triangle whose opening shape on the screw groove 10 side (that is, in the accommodating portion 1c) has an acute angle at the discharge side corner. Further, the notch 15d is opened on the screw groove 10 side (that is, in the accommodating portion 1c), the discharge port wall surface 1b of the fixed port 15b, and the outer peripheral surface of the accommodating portion 1c.

  As described above, also in the screw compressor 100 according to the second embodiment, the fixed port 15b is formed in a shape that can reduce the leakage loss in a range that does not increase the discharge loss in consideration of the discharge area and the volume that change according to the screw rotation angle. Since it formed, it can be set as a highly efficient screw compressor with a comprehensively small loss similarly to Embodiment 1. FIG. Further, in the screw compressor 100 according to the second embodiment, the discharge area adjusting portion is formed like a notch 15d, so that leakage from the fixed port 15b to the gate rotor support chamber 6 is made as compared with the first embodiment. The discharge area in the screw rotation angle range having a large volume change can be increased while maintaining the flow path length.

Embodiment 3 FIG.
Moreover, you may form a discharge area adjustment part as follows, for example. Items that are not particularly described in the third embodiment are the same as those in the first embodiment.

FIG. 14 is a development view of the inner wall surface of the accommodating portion 1c and the outer peripheral surface of the screw rotor 4 of the screw compressor 100 according to Embodiment 3 of the present invention. FIG. 15 is a perspective view of the discharge port 15 of the screw compressor 100 as seen from the inside of the accommodating portion 1c.
As shown in FIGS. 14 and 15, the screw compressor 100 according to the third embodiment is provided with a screw groove 10 side (on the discharge side corner of the fixed port 15 b (discharge port wall surface 1 b) as a discharge area adjustment unit. That is, a through hole 15e communicating with the inside of the housing portion 1c is formed. The other end of the through hole 15e communicates with the discharge port wall surface 1b of the fixed port 15b. The other end of the through hole 15e may be communicated with the outer peripheral surface of the housing portion 1c.

  As described above, also in the screw compressor 100 according to the third embodiment, the fixed port 15b is formed in a shape that can reduce the leakage loss in a range that does not increase the discharge loss in consideration of the discharge area and volume that change according to the screw rotation angle. Since it formed, it can be set as the highly efficient screw compressor with a small loss comprehensively similarly to Embodiment 1 and Embodiment 2.

Embodiment 4 FIG.
For example, the discharge area adjusting unit may be formed as follows. Items that are not particularly described in the fourth embodiment are the same as those in the second embodiment.

FIG. 16 is a development view of the inner wall surface of the accommodating portion 1c and the outer peripheral surface of the screw rotor 4 of the screw compressor 100 according to Embodiment 4 of the present invention. FIG. 17 is a perspective view of the discharge port 15 of the screw compressor 100 as viewed from the inside of the accommodating portion 1c.
As shown in FIGS. 16 and 17, in the screw compressor 100 according to the fourth embodiment, a notch 15f is formed at the discharge-side corner of the fixed port 15b (discharge port wall surface 1b) as a discharge area adjusting unit. ing. The notch 15f is formed in a right triangle whose opening shape on the screw groove 10 side (that is, in the accommodating portion 1c) has an acute angle at the discharge side corner. Here, unlike the notch 15d shown in the second embodiment, the notch 15f has a shape that does not open to the outer peripheral surface of the accommodating portion 1c. In other words, the notch 15f is open to the screw groove 10 side (that is, in the accommodating portion 1c) and the discharge port wall surface 1b of the fixed port 15b, and is formed between the outer peripheral surface of the screw rotor 4 and the inner wall surface of the accommodating portion 1c. It is deep enough to expand the gap.

  As described above, also in the screw compressor 100 according to the fourth embodiment, the fixed port 15b is formed in a shape that can reduce the leakage loss in a range that does not increase the discharge loss in consideration of the discharge area and volume that change according to the screw rotation angle. Since it formed, it can be set as a highly efficient screw compressor with a comprehensively small loss similarly to Embodiment 2. FIG. Further, the screw compressor 100 according to the fourth embodiment can easily process the discharge area adjusting section as compared with the second embodiment by forming the discharge area adjusting section like the notch 15f. .

Embodiment 5 FIG.
For example, the discharge area adjusting unit may be formed as follows. Items that are not particularly described in the fifth embodiment are the same as those in the first embodiment.

FIG. 18 is a development view of the inner wall surface of the accommodating portion 1c and the outer peripheral surface of the screw rotor 4 of the screw compressor 100 according to Embodiment 5 of the present invention. FIG. 19 is a perspective view of the discharge port 15 of the screw compressor 100 as viewed from the inside of the accommodating portion 1c.
As shown in FIGS. 18 and 19, in the screw compressor 100 according to the fifth embodiment, a notch 15g is formed at the discharge side corner of the fixed port 15b (discharge port wall surface 1b) as a discharge area adjusting unit. ing. The notch 15g has a rectangular opening shape on the screw groove 10 side (that is, in the accommodating portion 1c). Here, unlike the notch 15c shown in Embodiment 1, the notch 15g has a shape that does not open to the outer peripheral surface of the accommodating portion 1c. In other words, the notch 15g is open to the screw groove 10 side (that is, inside the accommodating portion 1c) and the discharge port wall surface 1b of the fixed port 15b, and is between the outer peripheral surface of the screw rotor 4 and the inner wall surface of the accommodating portion 1c. It is deep enough to expand the gap.

  As described above, also in the screw compressor 100 according to the fifth embodiment, the fixed port 15b is formed in a shape that can reduce the leakage loss in a range that does not increase the discharge loss in consideration of the discharge area and volume that change according to the screw rotation angle. Since it formed, it can be set as a highly efficient screw compressor with a comprehensively small loss similarly to Embodiment 1. FIG. Further, the screw compressor 100 according to the fifth embodiment can easily process the discharge area adjusting section as compared with the first embodiment by forming the discharge area adjusting section like a notch 15g. .

Embodiment 6 FIG.
The discharge area adjusting section (notch 15c, notch 15d, through hole 15e, notch 15f, notch 15g) shown in the first to fifth embodiments is not necessarily provided. For example, a high-efficiency screw compressor can be obtained similarly to the screw compressor 100 shown in each of the above embodiments without forming the discharge area adjusting section. Note that items not particularly described in the sixth embodiment are the same as those in the first embodiment.

FIG. 20 is a development view of the inner wall surface of the accommodating portion 1c and the outer peripheral surface of the screw rotor 4 of the screw compressor 100 according to Embodiment 6 of the present invention. FIG. 21 is a perspective view of the discharge port 15 of the screw compressor 100 as viewed from the inside of the accommodating portion 1c.
As shown in FIGS. 20 and 21, the screw compressor 100 according to the sixth embodiment has a configuration in which the discharge area adjusting portion is not formed at the discharge side corner of the fixed port 15 b (discharge port wall surface 1 b). ing.

  As can be seen from FIG. 10, the screw rotation angle at which the discharge side corner of the fixed port 15b (discharge port wall surface 1b) starts to have a large influence as the discharge area region is after the vicinity of 140 °. Further, as can be seen from FIG. 8, this range is a range in which the volume change is small. For this reason, when there is a sufficient gap between the outer peripheral surface of the screw rotor 4 and the inner wall surface of the accommodating portion 1c, the gap functions as a discharge area adjusting portion.

  As described above, in the screw compressor 100 according to the sixth embodiment, since the discharge area adjusting portion is not formed at the discharge side corner of the fixed port 15b (discharge port wall surface 1b), the arrow (3) in FIG. It is possible to further reduce the leakage of the refrigerant in the path shown, and to further improve the efficiency of the screw compressor 100.

  In each of the above-described embodiments (Embodiments 1 to 6), the slide valve 12 is provided (in other words, a part of the peripheral wall of the discharge port 15 is configured by the discharge-side end face 12d of the slide valve 12). ) The screw compressor 100 has been described. Not limited to this, even in the case of a screw compressor not provided with the slide valve 12, the discharge port 15 is formed in the shape shown in each of the above-described embodiments, so that highly efficient screw compression with a small overall loss is achieved. Can be a machine.

  In the above embodiments (Embodiments 1 to 6), the twin type screw compressor 100 provided with the two gate rotors 7 has been described. Not limited to this, even in a single type screw compressor provided with one gate rotor, by making the discharge port 15 in the shape shown in each of the above embodiments, the overall efficiency is small and the loss is small. It can be a screw compressor.

  DESCRIPTION OF SYMBOLS 1 Casing, 1a Casing lip surface, 1b Discharge port wall surface, 1c accommodating part, 1d Gate rotor opening, 2 High pressure side bearing, 3 Low pressure side bearing, 4 Screw rotor, 5 Gate rotor support, 5a bearing, 6 Gate rotor support Chamber, 7 Gate rotor, 7a Gate rotor teeth, 8 Electric motor, 9 Screw shaft, 10 Screw groove, 11 Compression chamber, 12 Slide valve, 12d Discharge end face, 14 Slide hole, 15 Discharge port, 15a Variable port, 15b Fixed port 15c notch, 15d notch, 15e through hole, 15f notch, 15g notch, 100 screw compressor.

Claims (8)

A screw rotor having a plurality of screw grooves formed on the outer peripheral surface;
A gate rotor having a plurality of teeth meshed with the screw groove formed on the outer periphery; and
A casing forming an accommodating portion in which the screw rotor is accommodated;
A discharge port that opens into the housing;
With
The casing is formed with an opening for a gate rotor that opens to the accommodating portion,
The outer periphery of the gate rotor is inserted into the accommodating portion via the gate rotor opening, and the screw groove and the teeth are engaged with each other.
As the screw rotor rotates, the refrigerant is sucked into the compression chamber, which is a space surrounded by the inner wall of the casing (the peripheral wall of the housing portion), the screw rotor, and the gate rotor, and is compressed and compressed from the discharge port. In screw compressors that discharge the refrigerant,
The screw compressor, wherein a distance between the discharge port and the gate rotor opening is relatively longer on the discharge side than on the suction side along the rotation axis direction of the screw rotor.   2. The screw compressor according to claim 1, wherein the casing is formed with a discharge area adjusting section for adjusting a discharge area at a discharge side corner of the discharge port.   The discharge area adjusting portion is formed at a discharge side end portion of the discharge port so as to open to the housing portion, and the opening shape in the housing portion is a notch formed in a rectangular shape. Item 3. The screw compressor according to Item 2.   The discharge area adjusting portion is formed at a discharge side end portion of the discharge port so as to open to the accommodating portion, and the opening shape in the accommodating portion is a notch formed in a triangular shape. Item 3. The screw compressor according to Item 2.   The screw compressor according to claim 2, wherein the discharge area adjusting portion is a through hole communicating with the housing portion.   The screw compressor according to any one of claims 2 to 5, wherein the discharge area adjusting portion is opened in the inside of the housing portion and in a wall surface of the discharge port.   The screw compressor according to any one of claims 1 to 6, wherein a suction side surface portion of the discharge port is formed along the inclination of the screw groove in the casing. An electric motor connected to the screw rotor via a drive shaft and rotating the screw rotor;
The screw compressor according to any one of claims 1 to 7, wherein the electric motor is an electric motor driven by an inverter.