JP2004251225A - Capacity controller of screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a vacuum of a chamber on a secondary side (downstream of a valve plate) of a suction port by an inexpensive structure and to avoid the separation vibration of a screw rotor tooth face when performing unload operation. <P>SOLUTION: A three-way solenoid valve is used as an air releasing solenoid valve 1. A first open port 1a of the three-way solenoid valve is connected with the discharge side of a compressor, and a second open port 1b is connected with an operation chamber 3. A third open port 1c is connected with the secondary side 5b of the suction port through a pipe 9 for reducing a vacuum. When performing suction-unloading, air in the operation chamber flows to the secondary side of the suction port by communicating the second open port with the third open port of the three-way solenoid valve to reduce a vacuum of the chamber on the secondary side of the suction port. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an intake port provided on the suction side of a screw compressor, a valve plate for opening and closing the intake port, a piston connected to the valve plate, a working chamber as a pressurizing chamber for operating the piston, and the like. The present invention relates to a capacity control device for a screw compressor having a capacity control device composed of an oil-cooled screw compressor particularly configured to inject oil into a compression chamber to cool compression heat. is there.
[0002]
[Prior art]
As a conventional technique for suppressing the generation of noise at the time of capacity control operation (unloading), there is one described in Patent Document 1. This is a method of applying a load to the female rotor and avoiding tooth surface separation vibration.
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-110766
[Problems to be solved by the invention]
FIG. 2 shows the structure of a displacement controller used in a conventional oil-cooled screw compressor. The capacity control operation by the capacity controller includes a suction unload operation in which air flows as shown by a dotted arrow in the figure and an integral unload operation in which air flows as shown by a solid line in the figure. In the suction unload operation using the normally open type capacity controller, the set pressure is sensed by the pressure regulating valve 2, the compressed air flows into the working chamber 3 of the capacity controller, and the piston 4 in the capacity controller moves to the left. The intake port 13 is closed by the valve plate 6. In the integral unload operation, when the set pressure is detected by the pressure sensor, the air release solenoid valve 1 is opened, the compressed air flows to the working chamber 3 of the capacity controller, the piston is moved to the left, and the intake port is closed. It is.
[0004]
In both operations, since the operation is performed with the intake port 13 of the displacement controller almost closed, the intake side is almost completely vacuum, and the discharge side is a screw compressor of 0.69 (MPa) specification. .78 (MPa) and about 0.30 (MPa) during integral unloading. In general, when the degree of vacuum on the intake side is high, noise is increased due to vibration of the tooth surface separation of the screw rotor or the like. Therefore, measures are taken by the following method, for example.
[0005]
The first method is to install a path having a vacuum relief valve to sense the pressure in the chamber 5 on the secondary side of the intake of the capacity controller and automatically reduce the degree of vacuum when the degree of vacuum reaches a certain level or more. is there. In this method, the vacuum relief valve 11 is required, and a piping work for that purpose is also required.
[0006]
The second method is to adjust the amount of air entering the capacity control device working chamber 3 or the amount of air exhausted from the working chamber by the relief valve 12 to reduce the contact surface pressure between the unloader cover 7 and the valve plate 6 to reduce the capacity. This is to relieve the pressure in the room 5 on the secondary side of the controller. In this method, the compressed air passes through the relief valve 12 before entering the working chamber 3 so as to adjust the pressure and the amount of compressed air entering the working chamber. And adjusting the pressure and the amount of air while discharging compressed air from the working chamber. However, this second method also requires a relief valve, a relief valve mounting part, and a pipe connection operation.
As described above, in the prior art, any of the methods has a problem in that the piping path for relaxing the vacuum is complicated, and the cost of parts is increased.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a capacity control device for a screw compressor that performs an unload operation by closing an intake port of a screw compressor with a valve plate, thereby reducing the vacuum relaxation of a room on the secondary side of the intake port (downstream of the valve plate). Another object of the present invention is to provide a simple structure for avoiding separation vibration of the screw rotor tooth surface during unloading operation.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an intake port provided on a suction side of a screw compressor, a valve plate for opening and closing the intake port, a piston connected to the valve plate, and a valve for operating the piston. In a capacity control device of a screw compressor including a capacity control device including a working chamber that is a pressurizing chamber, a path for guiding compressed air to the working chamber, and an electromagnetic valve provided in the compressed air path, It is characterized by comprising a path for vacuum relief communicating the room on the downstream side of the valve plate at the intake port with the working chamber, and an electromagnetic valve provided on the path for vacuum relief.
[0009]
Here, the solenoid valve provided in the compressed air path is a three-way solenoid valve, and one open port of the three-way solenoid valve is communicated with a room on the valve plate downstream side of the intake port to thereby provide a solenoid valve. It is preferable to configure the vacuum relaxation path having the following.
[0010]
Further, a path connected to the working chamber via a pressure regulating valve is further provided, and compressed air entering the working chamber via the pressure regulating valve during suction unload operation is drawn into the suction port via the vacuum relaxation path. By circulating to the outlet secondary side, vacuum relaxation at the time of suction unload operation may be performed. Further, it is preferable to provide an air discharge path that communicates the working chamber with the valve plate upstream of the intake port.
[0011]
Other features of the present invention include an intake port provided on the suction side of the screw compressor, a valve plate for opening and closing the intake port, a piston connected to the valve plate, and a pressurizing chamber for operating the piston. In a capacity control device for a screw compressor including a capacity control device including a working chamber, a compressed air path for guiding compressed air from a discharge side of the compressor to the working chamber, and a compressed air path provided in the compressed air path. A three-way solenoid valve, a first opening of the three-way solenoid valve is connected to the compressor discharge side, a second opening is connected to the working chamber, and a third opening is downstream of the valve plate at the intake port. A side chamber is connected via a vacuum alleviation path, and further includes an air discharge path communicating the working chamber with the valve plate upstream side of the intake port.At the time of suction unload operation, air in the working chamber is Connect the second and third open ports of the three-way solenoid valve. As the state, it flowed into the inlet port the secondary side, and performs vacuum relaxation inlet secondary rooms.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG. 1 while referring to FIG. In FIG. 1, portions denoted by the same reference numerals as those in FIG. 2 indicate the same or corresponding portions.
[0013]
Referring to FIG. 2, a path for relaxing the vacuum will be described. The air flow at the time of integral unloading passes through the NO-COM of the air discharge solenoid valve 1 and enters the working chamber 3 through the NO-COM of the air discharge solenoid valve 1 and becomes a path through which the air is discharged through the air discharge pipe 10. . At this time, the internal pressure of the working chamber 3 rises, and the piston 4 and the valve plate 6 are pushed by the primary side (upstream side of the valve plate) 5a of the intake port, so that the valve plate 6 comes into contact with the unloader cover 7 and the intake port 13 Is closed. The air inlet 13 is not completely closed, but air is sucked through the gap between the valve plate 6 and the cover 7. The degree of vacuum in the room on the air inlet secondary side 5 b changes depending on the amount of air suction.
[0014]
The air flow at the time of suction unloading passes through the pressure regulating valve 2 and enters the working chamber 3 as shown by the dotted arrow, and becomes a path to be ventilated through the vent pipe 10. This is the same as at the time of integral unloading.
[0015]
In the conventional device, in order to alleviate the vacuum in the room on the secondary side 5b of the intake port, a path connecting the working chamber 3 and the secondary side 5b of the intake port is provided, and a relief valve 12 is provided on this path. As a result, the pressure in the working chamber 3 is adjusted, the contact surface pressure between the valve plate 6 and the unloader cover 7 is reduced, the amount of leakage from this clearance is increased, and the vacuum on the inlet side secondary side is relaxed. .
[0016]
Another method of reducing the vacuum in the inlet secondary room is to use a vacuum relief valve 11, which senses the degree of vacuum in the inlet secondary 5b and, when the degree of vacuum is equal to or higher than the set vacuum degree, compresses the compressed air. Is caused to flow to the intake side secondary side 5b to reduce the vacuum.
[0017]
In both methods, a valve was required, in addition to the need for a mitigation valve, its piping connection, and mounting parts.
[0018]
An embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 1 denotes a discharge air solenoid valve provided in a compressed air pipe (compressed air path) 14 for communicating the discharge side of the screw compressor and the working chamber 3 of the displacement controller. As the valve 1, a three-way solenoid valve is used. The first opening 1a of the three-way solenoid valve 1 is connected to the compressor discharge side, and the second opening 1b is connected to the working chamber 3. Further, the third opening 1c is connected to the suction port secondary side 5b via a vacuum relaxation pipe (vacuum relaxation path) 9. The three-way solenoid valve 1 supplies electricity to the three-way solenoid valve at the time of starting unloading, integral unloading, and stopping, so that the first opening 1a and the second opening 1b are in communication with each other. The three-way solenoid valve is configured to be in a non-energized state so that the second open port 1b and the third open port 1c are in a communication state. Thereby, at the time of suction unloading, the air in the working chamber 3 is made to communicate with the second open port 1b and the third open port 1c of the three-way solenoid valve to the intake port secondary side 5b as shown by the dotted arrow. It is possible to flow, and it is possible to alleviate the vacuum in the room on the inlet side secondary side 5b. In the drawing, the solid arrows indicate the air flow during integral unloading, and the dotted arrows indicate the air flow during suction unloading.
[0019]
Further, in the oil-cooled screw compressor, it is necessary to prevent the oil from flowing to the working chamber 3 side. In the present invention, however, the oil between the suction port secondary side 5b where the oil exists and the working chamber 3 is provided. Is opened and closed by the three-way solenoid valve 1, so that oil can be prevented from entering the working chamber.
[0020]
As described above, according to the present embodiment, the room at the third open port 1c and the suction port secondary side 5b of the three-way solenoid valve 1 installed in the pipe for sending compressed air to the working chamber is connected to the vacuum relief pipe. Since the connection is made at 9, there is no need to provide a vacuum relief valve, a relief valve, or a piping system for them, unlike the conventional art, so that the vacuum can be reduced at the time of suction unloading at low cost.
[0021]
That is, the degree of vacuum at the inlet secondary side 5b of the screw compressor is related to the noise problem due to the separation vibration of the tooth surface of the screw rotor. From the viewpoint of this noise problem, it is necessary to reduce the degree of vacuum as much as possible. . In the conventional vacuum relaxation method, installation of a relief valve, connection of piping, etc. are expensive, and valve adjustment work is also required. However, the present invention can solve the conventional problems. In addition, the use of the three-way solenoid valve eliminates the need for conventional valve adjustment.
[0022]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in the capacity control apparatus of a screw compressor which performs an unload operation by closing the suction port of a screw compressor with a valve plate, the vacuum relaxation of the room of the suction port secondary side (downstream of a valve plate) is inexpensive. The structure can be realized with a simple structure, and separation vibration of the screw rotor tooth surface during the unloading operation can be avoided.
[Brief description of the drawings]
FIG. 1 is a system diagram illustrating an embodiment of a capacity control device for a screw compressor according to the present invention.
FIG. 2 is a system diagram illustrating a conventional device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Air discharge solenoid valve (3-way solenoid valve), 2 ... Pressure regulating valve, 3 ... Working chamber, 4 ... Piston, 5a ... Inlet primary side, 5b ... Inlet secondary side, 6 ... Valve plate, 7 ... Unloader cover, 8 ... Unloader body, 9 ... Vacuum relief pipe, 10 ... Vacuum release pipe, 11 ... Vacuum relief valve, 12 ... Relief valve, 13 ... Inlet, 14 ... Compressed air pipe.

Claims (5)

It is composed of an intake port provided on the suction side of the screw compressor, a valve plate for opening and closing the intake port, a piston connected to the valve plate, a working chamber that is a pressurizing chamber for operating the piston, and the like. In a capacity control device of a screw compressor having a capacity control device,
A path for leading compressed air to the working chamber;
An electromagnetic valve provided in the compressed air path;
A path for vacuum relaxation communicating the chamber on the valve plate downstream side of the intake port and the working chamber,
And a solenoid valve provided in the vacuum relaxation path. In claim 1, the solenoid valve provided in the compressed air path is a three-way solenoid valve, and one open port of the three-way solenoid valve communicates with a room on the valve plate downstream side of the intake port, A capacity control device for a screw compressor, wherein the vacuum relaxation path having an electromagnetic valve is configured. 3. The vacuum relief path according to claim 1, further comprising a path connected to the working chamber via a pressure regulating valve, wherein compressed air entering the working chamber via the pressure regulating valve during suction unload operation is passed through the vacuum relief path. 4. A capacity control device for a screw compressor, which circulates through the intake port to the secondary side of the intake port to relieve vacuum during suction unload operation. The capacity control device for a screw compressor according to any one of claims 1 to 3, further comprising an air discharge path that communicates the working chamber with a valve plate upstream of the intake port. It is composed of an intake port provided on the suction side of the screw compressor, a valve plate for opening and closing the intake port, a piston connected to the valve plate, a working chamber that is a pressurizing chamber for operating the piston, and the like. In a capacity control device of a screw compressor having a capacity control device,
A compressed air path for guiding compressed air from the discharge side of the compressor to the working chamber;
A three-way solenoid valve provided in the compressed air path;
A first opening of the three-way solenoid valve is connected to the compressor discharge side, a second opening is connected to the working chamber, and a third opening is provided in the chamber on the downstream side of the valve plate in the suction port for vacuum relaxation. Connected via a path,
Furthermore, an air discharge path communicating the working chamber and the valve plate upstream of the intake port is provided,
During the suction unload operation, the air in the working chamber is caused to flow to the secondary side of the intake port with the second open port and the third open port of the three-way solenoid valve in communication with each other, and the vacuum in the secondary chamber of the intake port is relaxed. A capacity control device for a screw compressor.

Images