JPH0688581A - Screw compressor - Google Patents

Abstract

PURPOSE:To provide a screw compressor that is able to improve the extent of performance by way of reducing a sectional area in a coolant filling hole, without decreasing the injection rate of a coolant. CONSTITUTION:This compressor is provided with an opening part 24 of a coolant filling hole installed a discharge side end face part vertical to a rotor shaft in a wall part of a rotor chamber at the front side in the rotational direction of a screw rotor 15, a front side 26 lapping over a forward side tooth surface 25 of this screw rotor 15, and a rear side 28 lapping over a follow-up side tooth surface 27 of the screw rotor 15 at the rear side in the rotational direction, respectively, and in the state that this rear side 28 is overlapped with the follow-up side tooth surface 27 of the screw rotor 15, the front side 26 is formed in a position where this follow-up side tooth surface 27 is overlapped with the forward side tooth surface 25 forming a screw tooth together with this tooth surface 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw compressor provided with a coolant injection hole in a wall portion of a rotor chamber accommodating a screw rotor.

[0002]

2. Description of the Related Art Conventionally, a screw compressor of this type is known, and FIG. 6 shows a screw rotor 1 and a coolant injection hole 2 thereof.
And is shown. This screw compressor has a cooling liquid injection hole 2 having a circular cross section, which is bored by a drill, on a side surface portion of a wall portion of a rotor chamber accommodating the screw rotor 1 in parallel with a rotor axis, from which cooling is performed. For one purpose, for example, oil (in the case of an oil-cooled screw compressor), refrigerant (in the case of a heat pump, a refrigerator), or cooling water is injected so that the heat generated during gas compression is taken away by the heat of vaporization of the cooling liquid. It is the one. In addition, a cooling liquid injection hole similar to the above may be provided in an end surface portion of the wall portion of the rotor chamber perpendicular to the rotor axis.

[0003]

In the above-mentioned conventional device,
Since the coolant injection hole 2 has a circular cross section, the opening cross-sectional area of the coolant injection hole 2 that opens to one tooth groove of the screw rotor 1 as the screw rotor 1 rotates is only moderate. It won't change. FIG. 7 shows a state in which this cross-sectional area changes when the cooling liquid injection hole 2 has a diameter of 36 mm. The horizontal axis represents the rotor rotation angle (°), and the vertical axis represents the effective opening of the cooling liquid injection hole for one tooth groove. The ratio of the partial sectional area to the maximum value of the sectional area is taken. Further, the solid line shows the change of the above-mentioned ratio of the circular cooling liquid injection hole with respect to the female rotor and the broken line shows that of the male rotor, and the ideal change curves are shown by the two-dot chain line and the one-dot chain line.

On the other hand, the time during which the cooling liquid injection hole 2 is open to the one tooth groove is very short, and if it is attempted to inject a sufficient amount of the cooling liquid to cool the gas compression space during this period, the cooling liquid is cooled. It is necessary to enlarge the liquid injection hole 2. However, if the cooling liquid injection hole 2 is made large, there is a problem that gas leakage occurs between the adjacent tooth spaces of the screw rotor 1 via the cooling liquid injection hole 2 and the performance of the compressor deteriorates.
The amount of gas to be cooled is proportional to the cube of the outer diameter D of the screw rotor 1, whereas the amount of cooling liquid injected is the cooling liquid injection hole 2
Since it is proportional to the square of the inner diameter d of the screw compressor, the cross-sectional area of the cooling liquid injection hole 2 rapidly increases, especially when the screw compressor becomes large, and thus the cooling liquid injection hole 2 has a large adverse effect on the performance of the compressor. There is a problem of becoming. The present invention has been made to solve the above-mentioned conventional problems, and a screw compression that can improve the performance by reducing the cross-sectional area of the coolant injection hole without reducing the injection amount of the coolant. Is to provide a machine.

[0005]

In order to solve the above problems, the present invention provides a screw compressor having a cooling liquid injection hole opening in a wall portion of a rotor chamber accommodating the screw rotor. When the opening portion of the hole is provided on the side surface portion of the wall portion parallel to the rotor axis, the opening portion has a side that overlaps with the outer peripheral seal line of the screw rotor, and the side overlaps with the outer peripheral seal line. In addition, when the opening has a shape that does not protrude from between two adjacent outer peripheral seal lines, and when the opening is provided on the discharge side end surface portion of the wall portion that is perpendicular to the rotor axis, this opening portion Is a front side that overlaps the forward tooth surface of the screw rotor forward with respect to the rotation direction of the screw rotor, and a rear edge that overlaps the trailing tooth surface of the screw rotor rearward with respect to the rotation direction. A shape in which the opening does not protrude from between the tooth flank and the tooth flank forming the screw tooth together with the tooth flank of the screw rotor in a state in which any of these sides overlaps the tooth flank of the screw rotor. I assumed that.

[0006]

With the above-described structure, the cross-sectional area of the opening of the cooling liquid injection hole that opens into the tooth groove of the screw rotor changes rapidly, so that the screw rotor has a small rotation angle. Then, the required amount of cooling liquid is injected.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show an oil-cooled screw compressor according to a first embodiment of the present invention, which is used as a compressor for a heat pump, and the heat pump itself is separated from this compressor by an oil separation and recovery not shown. The condenser, the condenser, the expansion valve, and the evaporator form a well-known closed loop back to the compressor. Further, this heat pump has an oil reservoir at the lower part of the oil separation / recovery device, and is provided with an oil supply flow path from here to at least an oil cooler to an oil injection point in the compressor described below. This compressor has a pair of male and female screw rotors 15 and 16 housed in a rotor chamber 14 in a casing 13 having one end opened to the suction port 11 and the other end opened to the discharge port 12, and bearing parts 17, 18 are provided. The screw rotors 15 and 16 are rotatably supported by.
Further, bearings 17, 18 and oil-compressing holes 19, 20, 21 for lubricating the gas compression space in the rotor chamber 14 are provided, and the oil supply passages are used to cool these holes. It is formed to feed oil.

Furthermore, the rotor shaft 2 on the wall of the rotor chamber 14
2 is provided with a cooling liquid injection hole 23 that is open at the end face on the discharge side, and a part of the refrigerant liquid condensed in the condenser is passed through a cooling liquid supply flow path (not shown). Two
It is supposed to be sent to 3. FIG. 2 shows II-II of FIG.
Only the portions of the screw rotors 15 and 16 in the line cross section are shown, and the opening 24 of the coolant injection hole 23, which does not actually appear in the II-II cross section, has a relative positional relationship with the screw rotors 15 and 16. , And for the purpose of explaining the shape, cross hatching is added. As shown in the figure, the opening 24 of the coolant injection hole 23 is located at the front side with respect to the direction of rotation of the screw rotor 15 which is the female rotor, as shown by the arrow.
There is a front side 26 that overlaps with the forward-side tooth surface 25 of the screw rotor 15, and a rear side 28 that overlaps with the following-side tooth surface 27 of the screw rotor 15 on the rear side with respect to the rotation direction. The front side 2 is overlapped with the trailing side tooth surface 27 of the screw rotor 15 and at a position overlapping with the advancing side tooth surface 25 forming the screw teeth.
6 is formed.

Then, the refrigerant liquid is injected from the cooling liquid injection hole 23 into the gas compression space, the refrigerant liquid is vaporized in this space, and the heat of vaporization is used to remove the heat generated by the gas compression. It is like this. Here, since the opening 24 has the above-described shape, when the trailing side tooth surface 27 rotates from the state shown in FIG. 2, the opening is suddenly opened in one tooth groove of the screw rotor 15 over the entire length of the rear side 28. Then, the cross-sectional area of the opening is widened, and the cross-sectional area of the opening is narrowed after the forward tooth surface 25 of the screw tooth shown in FIG. As they rotate, the opening 2
4 is closed at once.

FIG. 3 shows the case of this embodiment corresponding to FIG. 7, in which the horizontal axis and the vertical axis are the same as above, and the effective aperture under the same conditions as those shown in FIG. The change of the above-mentioned ratio of sectional area is shown. Of the two curves shown by the solid line in FIG. 3, the one on the left side shows the case of this embodiment,
The curve indicated by the chain double-dashed line that overlaps this is the same as the curve on the left side in the case of the conventional compressor in FIG. 7. As is clear from the figure, the opening cross-sectional area changes abruptly, and as a result, a required amount of the refrigerant liquid is injected within a small rotation angle of the screw rotor 15. Therefore, the cross-sectional area of the cooling liquid injection hole 23 can be reduced and the performance of the compressor can be improved without reducing the injection amount of the refrigerant liquid.

In the above embodiment, only one cooling liquid injection hole 23 is provided, but a plurality of cooling liquid injection holes 23 may be provided. Further, in the above-described embodiment, the trailing edge 28 is the trailing edge 28 of the screw rotor 15.
Although the front side 26 is formed at a position where the front side 26 overlaps with the advancing side tooth surface 25 that forms the screw tooth in the overlapping state with the front side 26, the rear side 28 and the front side 26 are not necessarily the above tooth surfaces at the same time. It is not necessary to form a shape that overlaps with the trailing side tooth surface 27 of the screw rotor 15 with the trailing side 28 overlapping the trailing side tooth surface 27 of the screw rotor 15.
Along with this, the shape may be such that the front side 26 is formed at a position that does not protrude from the front tooth surface 25 that forms the screw tooth.

FIG. 4 is a view corresponding to FIG. 2 and shows only the screw rotors 15 and 16 and the opening 24a of the coolant injection hole 23 of the screw compressor according to the second embodiment of the present invention. For parts other than those shown in the figure,
The description is omitted because it is similar to the embodiment. This opening 24
a is a front side 32 that overlaps the forward-side tooth surface 31 of the screw rotor 16 on the front side with respect to the rotation direction of the screw rotor 16, and a trailing-side tooth surface 33 of the screw rotor 16 on the rear side with respect to the rotation direction. The trailing side 34 overlaps with the trailing side tooth surface 33 of the screw rotor 16, and the trailing side tooth surface 33 and the advancing side tooth surface 31 that forms the screw tooth together with the trailing side tooth surface 33. The front side 32 is formed at a position where it does not protrude from the space.

By providing the cooling liquid injection hole 23 having the opening 24a having such a shape, it is formed so as to improve the performance of the compressor by the same operation as that of the first embodiment. . Of the two curves indicated by the solid line in FIG. 3, the one on the right side shows the case of the present embodiment, and the curve shown by the two-dot chain line which overlaps with this is the same as the curve on the right side in the case of the conventional compressor in FIG. Is. As is clear from the figure,
The change in the cross-sectional area of the opening is abrupt. In addition,
Also in the above-mentioned embodiment, the example in which only one cooling liquid injection hole 23 is provided is shown, but a plurality of cooling liquid injection holes 23 may be provided. Further, in the first and second embodiments, if the openings 24, 24a are shaped so as not to protrude from between the advancing side tooth surface 25 and the following side tooth surface 27, the front sides 26, 3
2, only one of the rear sides 28 and 34 may be shaped so as to overlap with the tooth surface of the screw rotor 15.

FIG. 5 shows only the screw rotor 16 and the opening 24b of the cooling liquid injection hole 23 of the screw compressor according to the third embodiment of the present invention. It is the same as the first embodiment except that the cooling liquid injection hole 23 having the portion 24 is not provided, and the description thereof will be omitted. Although the opening 24b does not actually appear in FIG. 5, it is shown with cross hatching for the same reason as in FIG. The opening 24b is provided on a side surface of the rotor chamber parallel to the rotor axis, and the outer peripheral seal line 4 of the screw rotor 16 is provided at this different position.
1 has two sides 42 and 43 overlapping with each other.
The space L1 of 43 is not larger than the space L2 between the adjacent outer peripheral seal lines 41, 41, that is, L1 ≦ L2.

By providing the cooling liquid injection hole 23 having the opening 24b having such a shape, it is formed so as to improve the performance of the compressor by the same operation as that of the first embodiment. . A plurality of cooling liquid injection holes 23 having the openings 24b may be provided, or may be provided only on the screw rotor 15 side, and the screw rotors 15 and 16 may be provided.
May be provided on either side of. Further, as in the case of the first and second embodiments, any one of the sides 42, 43 may be used as long as the opening 24b has a shape that does not protrude from between the two adjacent outer peripheral seal lines 41, 41. Only one of them may be shaped so as to overlap the outer peripheral seal line 41. The three types of coolant injection holes 2 of the first, second and third embodiments are used.
3 may be installed side by side. Further, the screw compressor according to the present invention is not limited to the one applied to a heat pump, and other application examples include, for example, a refrigerator, various gas compression devices, and a water injection type compression device for LNG compression. The cooling liquid to be injected is not limited to the refrigerant and may be oil or water.
Therefore, the oil injection hole 21 shown in FIG. 1 is also a kind of the coolant injection hole in the present invention, and its opening has the same shape as the opening 24b shown in FIG. Furthermore, the present invention is not limited to oil cooled screw compressors.

[0016]

As is apparent from the above description, according to the present invention, in the screw compressor having the cooling liquid injection hole opened in the wall portion of the rotor chamber accommodating the screw rotor, the cooling liquid injection hole is provided. When the opening is formed on a side surface of the wall parallel to the rotor axis, the opening has a side that overlaps with the outer peripheral seal line of the screw rotor, and the side is overlapped with the outer peripheral seal line. , Adjacent 2
If the opening has a shape that does not stick out between the outer peripheral seal lines of the book, and if the opening is provided on the discharge side end face of the wall that is perpendicular to the rotor axis, this opening should be rotated. At least one of a front side that overlaps the forward-side tooth surface of the screw rotor on the front side with respect to the direction, and a rear side that overlaps on the trailing-side tooth surface of the screw rotor on the rear side with respect to the rotation direction. In a state in which any one of these sides overlaps the tooth surface of the screw rotor, the opening does not protrude from between the tooth surface and the tooth surface forming the screw teeth with the tooth surface.

For this reason, since the change in the opening cross-sectional area of the cooling liquid injection hole opening into one tooth groove of the screw rotor becomes abrupt, the required amount of cooling liquid can be obtained within a small rotation angle of the screw rotor. Is injected, and the effect of being able to improve the performance of the compressor by reducing the cross-sectional area of the cooling liquid injection hole without reducing the injection amount of the cooling liquid is provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an oil-cooled screw compressor according to a first embodiment of the present invention.

FIG. 2 is a view showing a screw rotor and an opening portion of a coolant injection hole in a cross section taken along line II-II of FIG.

FIG. 3 is a diagram showing the relationship between the rotation angle of the screw rotor and the ratio of the effective opening cross-sectional area for one tooth groove of the cooling liquid injection hole to the maximum value of the cross-sectional area.

FIG. 4 is a view corresponding to FIG. 2 and showing a screw rotor and an opening portion of a coolant injection hole of a screw compressor according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a screw rotor of a screw compressor according to a third embodiment of the present invention and openings of cooling liquid injection holes.

FIG. 6 is a view showing a screw rotor of a conventional screw compressor and openings of cooling liquid injection holes.

FIG. 7 is a diagram showing the relationship between the rotation angle of the screw rotor and the ratio of the effective opening cross-sectional area for one tooth groove of the cooling liquid injection hole to the maximum value of the cross-sectional area.

[Explanation of symbols]

14 rotor chamber 15 and 16 screw rotor 23 cooling liquid injection hole 24, 24a and 24b
Opening 25,31 Forward tooth flank 26,32 Front edge 27,33 Following tooth flank 28,34 Rear edge 41 Peripheral seal line 42,43 Side L1 Two side gap L2 Perimeter seal line gap

Claims (1)

[Claims] 1. A screw compressor having a cooling liquid injection hole opened in a wall portion of a rotor chamber accommodating a screw rotor, wherein an opening portion of the cooling liquid injection hole is a side surface portion of the wall portion parallel to a rotor axis. In this case, the opening has a side that overlaps with the outer peripheral seal line of the screw rotor, and in a state where this side overlaps with the outer peripheral seal line, the opening is between the two outer peripheral seal lines adjacent to each other. When the opening is provided on the discharge side end surface of the wall perpendicular to the rotor axis, the opening of the opening should be forward with respect to the rotation direction of the screw rotor. It has at least one of a front side overlapping with the side tooth surface and a rear side overlapping with the following side surface of the screw rotor on the rear side with respect to the rotation direction. A screw compressor having a shape in which the above-mentioned opening does not stick out between the tooth surface of this rotor and the tooth surface forming the screw teeth together with the tooth surface of the rotor.