JPH0642474A - Single screw compressor - Google Patents

Abstract

PURPOSE:To prevent the generation of seizure between a screw rotor and a casing inner cylinder covering the outer peripheral part of the screw rotor by reducing the difference of thermal expansion between both. CONSTITUTION:The front part of a partitioning wall 8 for partitioning a low pressure chamber 6 which communicates to a suction side and a high pressure chamber 7 which communicates to a discharge side is erected in close to the edge surface part on the suction side in the axial direction of a screw rotor 1 in close to the low pressure chamber 6, at the position averting from the opened port part to the low pressure chamber 6 side which is formed on a casing inner cylinder 4, i.e., a suction port 41 which is formed by cutting one side contiguous part of a gate rotor 2 and a bypass port 42 which is formed by cutting the installation part of a capacity control valve 3, and the casing inner cylinder 4 is brought into contact in a wide range for the high pressure chamber 7, and the excessive cooling from the low pressure chamber 6 is prevented, and the difference of thermal expansion between the screw rotor 1 and the casing inner cylinder 4 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single screw compressor which is used as a refrigerant compressor of a refrigerator by engaging one or more gate rotors with a single screw rotor.

[0002]

2. Description of the Related Art Conventionally, this type of compressor has been disclosed in Japanese Utility Model Laid-Open No. 63-9.
As disclosed in Japanese Patent Publication No. 485 and shown in FIG. 6, a screw rotor R having a screw groove M, a gate rotor (not shown) engaged with the screw rotor R, and a slide type rotor attached to an outer peripheral portion of the screw rotor R are provided. A capacity control valve V, a casing inner cylinder T that covers the outer peripheral portion of the screw rotor R, and a casing outer cylinder C that constitutes an outer frame are provided, and between the inner cylinder T and the outer cylinder C, the screw rotor R A partition W that divides a low pressure chamber L communicating with the suction side and a high pressure chamber H communicating with the discharge side
Is provided. In this case, in the casing inner cylinder T, the suction port is opened adjacent to the one end surface of the gate rotor, and the bypass port B is opened corresponding to the attached portion of the capacity control valve V. Therefore, in order to avoid the opening to the suction chamber L side, the partition wall W is erected at a position closer to the rear side of the screw rotor R on the axial discharge side.

[0003]

However, if the partition wall W is erected at the position closer to the rear portion of the screw rotor R as described above, the casing inner cylinder T is strongly influenced by the low temperature chamber L having a low temperature. Therefore, the casing inner cylinder T hardly thermally expands with respect to the thermal expansion amount of the screw rotor R, and there is a problem that seizure occurs between the screw rotor R and the casing inner cylinder T.

That is, for example, when the liquid refrigerant accumulates inside the low-pressure chamber L due to a wet operation, the temperature of the liquid refrigerant is almost equal to the saturation temperature equivalent to the suction pressure, and -20 ° C. under severe operating conditions such as heating. The following also applies, and the casing inner cylinder T that comes into contact with this low-temperature liquid is considerably cooled. On the other hand, the discharge gas temperature reaches 100 ° C. or higher, and the temperature of the screw rotor R rises to 50 ° C. or higher even if the cooling by the oil injection is also used. Therefore, the temperature difference between the casing inner cylinder T and the screw rotor R becomes 50 ° C. or more, and in the screw rotor R having a diameter of 100 mm, the diameter changes by about 50 μm due to thermal expansion, and the temperature difference between the casing inner cylinder T and The seal bulges outward beyond the normally secured seal gap and seizure occurs with the casing inner cylinder T. In addition, in order to avoid this, the screw rotor R
When a large gap is secured between the casing and the inner cylinder T in anticipation of thermal expansion, the amount of leakage through the gap increases during normal operation, which causes a problem of performance deterioration.

In the present invention, the casing inner cylinder covering the outer peripheral portion of the screw rotor is prevented from being strongly affected by the temperature from the low pressure chamber, and the seal gap between the screw rotor and the casing inner cylinder is made particularly large. It is an object of the present invention to provide a single-screw compressor that can prevent seizure between the screw rotor and the casing inner cylinder while maintaining high performance.

[0006]

In order to achieve the above object, a screw rotor 1, a gate rotor 2 engaged with the screw rotor 1, and a capacity control valve 3 attached to the outer peripheral portion of the screw rotor 1 are provided. A casing inner cylinder 4 which covers an outer peripheral portion of the screw rotor 1 and has a suction port 41 opening to one side adjacent part of the gate rotor 2 and a bypass port 42 opening to an attached part of the capacity control valve 3; A casing outer cylinder 5 in which the inner cylinder 4 is disposed is provided, and between the inner cylinder 4 and the outer cylinder 5, the low pressure chamber 6 communicating with the suction side of the screw rotor 1 and the discharge side are communicated with each other. A single screw compressor provided with a partition wall 8 for partitioning the high pressure chamber 7, wherein the low pressure chamber 6 is provided at a position where a part of the partition wall 8 is located away from the openings of the suction port 41 and the bypass port 42.
Is erected near the end surface of the screw rotor 1 on the suction side in the axial direction.

[0007]

The casing inner cylinder 4 covering the outer peripheral portion of the screw rotor 1 is in contact with the high temperature high pressure chamber 7 except for the intake port 41 and the bypass port 42 which are openings for the low pressure chamber 6, so that the casing inner cylinder 4 Can be prevented from being excessively cooled from the low-pressure chamber 6, the temperature difference between the casing inner cylinder 4 and the screw rotor 1 can be reduced, and the difference in thermal expansion between the two can be reduced. It is possible to prevent seizure between the cylinder 4 and the screw rotor 1 in advance.

[0008]

1 shows a single screw compressor for compressing a refrigerant used in a refrigerator, having a screw groove 11a clearly shown in the development view of FIG. A screw rotor 1 coupled to the drive shaft 13, a pair of gate rotors 2 and 2 engaged with the screw rotor 1, and a pair of slide type rotors attached to the outer periphery of the screw rotor 1 and interlocking with the operating body 30. The capacity control valves 3, 3 and the screw rotor 1 and the outer peripheral portion of the bearing box 10 integrated with the rear portion are covered, and the gate rotors 2, 3
2 is a casing inner cylinder 4 having suction ports 41, 41 open to one side adjacent part 2 and bypass ports 42, 42 open to the attached parts of the respective capacity control valves 3, 3 and continuous to the discharge ports 43, 43.
And a casing outer cylinder 5 in which the inner cylinder 4 is disposed. Between the inner cylinder 4 and the outer cylinder 5, a low pressure chamber 6 communicating with the suction side of the screw rotor 1 and a discharge side communicating with the discharge side. A partition wall 8 for partitioning the high pressure chamber 7 is provided. 80
Is a through hole through which the capacity control valve 3 passes.

Then, the low-pressure low-temperature gas refrigerant or the wet refrigerant taken into the low-pressure chamber 6 from the suction port 14 shown in FIG. 3 is compressed along the screw groove 11, and the high-pressure high-temperature discharge gas is discharged from the high-pressure chamber 7. The oil recovery tank 17 in which the demisters 15 and 16 for oil separation are arranged is passed through, and taken out from the discharge pipe 18 to the outside.

With the above construction, as clearly shown in FIGS. 1 and 2, a part of the partition wall 8 that separates the low pressure chamber 6 and the high pressure chamber 7 serves as an inlet to the low pressure chamber 6. , 41 and the bypass ports 42, 42 are erected near the end surface of the screw rotor 1 facing the low-pressure chamber 6 on the suction side in the axial direction.

As a result, the casing inner cylinder 4 covering the outer peripheral portion of the screw rotor 1 is in contact with the high temperature high pressure chamber 7 except for the suction ports 41, 41 and the bypass ports 42, 42. It is possible to prevent the inner cylinder 4 from being excessively cooled from the low pressure chamber 6. Therefore, the temperature difference between the casing inner cylinder 4 and the screw rotor 1 can be reduced, the difference in thermal expansion between the two can be reduced, and the casing inner cylinder 4 and the screw rotor 1 can be reduced.
It is possible to prevent seizure from occurring between the casing inner cylinder 4 and the screw rotor 1 while maintaining high performance without unnecessarily increasing the seal gap between the and.

By the way, in the above embodiment, one screw rotor 1 is provided with the pair of gate rotors 2, 2 and the pair of capacity control valves 3, 3. However, as shown in FIGS. One gate rotor 2 for each screw rotor 1
Also, it can be applied to one provided with one capacity control valve 3.
In this type, the number of teeth of the gate rotor 2 is 11, which is the same as that shown in FIG. 1, whereas the number of teeth of the screw rotor 1, that is, the number of screw grooves 11b is about 3, and from the start of compression. The rotation angle of the screw rotor 1 required to complete the discharge is 200 degrees or more.

In this case, since there is only one intake port 41 opening on one side adjacent to the gate rotor 2 and one bypass port 42 opening on the attached part of the capacity control valve 3, respectively.
Most of the casing inner cylinder 4 that covers the outer peripheral portion of the screw rotor 1 can be brought into contact with the high-pressure chamber 7, and as a result,
Cooling of the casing inner cylinder 4 from the low-pressure chamber 6 can be further reduced, the temperature difference between the casing inner cylinder 4 and the screw rotor 1 can be further reduced, and seizure between them can be more reliably performed. Can be prevented. Moreover, in this device, since the rotation angle from the start of compression to the completion of discharge is 200 degrees or more, the volume change rate during the compression stroke can be reduced, and the flow rate change of the discharge gas can be reduced. Since the pressure loss can be reduced and the volume per screw groove 11b can be increased, the volume efficiency can be improved.

[0014]

As described above, according to the present invention, it is possible to prevent the casing inner cylinder 4 covering the outer peripheral portion of the screw rotor 1 from being excessively cooled from the low-temperature low-pressure chamber 6, and the screw rotor 1 and the casing inner cylinder. It is possible to prevent seizure from occurring between the screw rotor 1 and the casing inner cylinder 4 while maintaining high performance without increasing the seal gap between the screw rotor 1 and the inner cylinder 4.

[Brief description of drawings]

FIG. 1 is a perspective view of a partly cutaway essential portion showing a first embodiment of a single screw compressor of the present invention.

FIG. 2 is a development view of a screw rotor and a casing inner cylinder in the first embodiment.

FIG. 3 is a sectional view of the entire structure in the first embodiment.

FIG. 4 is a perspective view of a main part with a part cut away showing the second embodiment.

FIG. 5 is a development view of a screw rotor and a casing inner cylinder in the second embodiment.

FIG. 6 is a sectional view of a conventional single screw compressor.

[Explanation of symbols]

1; screw rotor, 2; gate rotor, 3; capacity control valve, 4; casing inner cylinder, 5; casing outer cylinder, 6;
Low pressure chamber, 7; High pressure chamber 7, 8; Partition wall, 41; Suction port, 4
2; Bypass port

Claims (1)

[Claims] 1. A screw rotor 1, a gate rotor 2 engaging with the screw rotor 1, a capacity control valve 3 attached to an outer peripheral portion of the screw rotor 1, an outer peripheral portion of the screw rotor 1, and the gate rotor. 2, a casing inner cylinder 4 having an intake port 41 opening to one side adjacent portion and a bypass port 42 opening to an attached portion of the capacity control valve 3, and a casing outer cylinder 5 having the inner cylinder 4 arranged therein. And a partition wall 8 is provided between the inner cylinder 4 and the outer cylinder 5 to partition a low pressure chamber 6 communicating with the suction side of the screw rotor 1 and a high pressure chamber 7 communicating with the discharge side of the screw rotor 1. In the compressor, an end face portion of the screw rotor 1 facing the low pressure chamber 6 in the axial direction on the suction side at a position where a part of the partition wall 8 avoids the openings of the suction port 41 and the bypass port 42. Standing up close A single screw compressor characterized in that