JPH02173369A - Capacity control device for gas compressor - Google Patents

Abstract

PURPOSE:To regulate the opening of a constant pressure valve according to the magnitude of a suction pressure and to enable continuously variable control of capacity by a method wherein the outlet of a constant pressure valve is connected to the gas suction side of a compressor, and the inlet thereof is connected to the actuating chamber of an unloader cylinder. CONSTITUTION:When a piston 2 is reciprocated, refrigerant gas flows through a suction passage 11 of a valve plate 3 after the passage of it through a suction cavity 5, and forcibly opens a suction valve 6 and is sucked in a compression chamber 12. Meanwhile, when the piston 2 is reciprocated, refrigerant gas of the compression chamber 12 is compressed, a delivery valve 7 is opened, and flows through a delivery passage 13 to a delivery chamber 8. In this case, the outlet of a constant pressure valve 30 is coupled to a low pressure gas pipe 27, and the inlet thereof is communicated to a working chamber 16 through a lead pipe 15. When the suction pressure of a compressor is, for example, reduced, through the increase of the opening of the constant pressure valve 30, the pressure of the working chamber 16 is reduced. This constitution rises an unloader piston 10 and increases a top clearance volume.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a capacity control device for a gas compressor such as a multi-cylinder refrigerator.

(Prior Art) An example of a conventional capacity control device for a multi-cylinder refrigerator is shown in FIG.

In Fig. 3, 1 is a cylinder, 2 is a piston, 3 is a valve plate, 4 is a cylinder head, 5 is a suction cavity, 6 is a suction valve, 7 is a discharge valve, 8 is a discharge chamber, 9 is an unloader cylinder, 10 is a This is the unloader piston.

When the piston 2 moves back, the refrigerant gas enters the suction cavity 5.
from the suction passage 11 bored in the valve plate 3 to the suction valve 6.
is pushed open and sucked into the compression chamber 12.

When the piston 2 moves forward, the refrigerant gas in the compression chamber 12 is compressed, pushes the discharge valve 7 open, passes through the discharge passage 13, enters the discharge chamber 8, and is discharged from there through a discharge pipe (not shown).

During unloading operation, by switching the three-way valve 14, the low pressure gas pipe 27 communicating with the gas inlet of the compressor is communicated with the working chamber 16 bounded above the unloader piston 10 via the pressure guiding pipe 15.

Then, the unloader screw I.'0 is pushed by the coil spring 17 and rises as shown in the figure, and opens.
8 opens, a chamber 19 bounded by the lower cam of the unloader piston 10 is communicated with the compression chamber 12 through the opening 18.

Thus, when the piston 2 rises to the top dead center, the volume of the chamber 19 and the opening 18 constitutes the I-knob clearance volume, so the flow rate of refrigerant scum discharged from the compression chamber 12 decreases.

During full rotary operation, the high pressure gas pipe 2 is connected to the gas discharge ROM of the compressor by switching the three-way valve 14.
8 is communicated with the pressure impulse pipe 15 to introduce high pressure gas into the working chamber 16.

Then, the unloader piston 10 descends and closes the opening 18, so the top clearance volume becomes zero and the amount of refrigerant gas discharged from the compression chamber 12 becomes maximum.

In FIG. 3, 20 is a cover that covers one end of the unloader cylinder 9, and 21 is a coil spring 17.
a pressure impulse pipe that communicates the suction air passage 11 with the chamber 22 in which the
23. 24 is a seal ring wrapped around the upper and lower ends of the unloader piston 10, 25 is a screw ring lightly mounted on the piston 2, and 26 is fixed to the lower surface of the unloader cylinder 9. It is a washer.

(Problems to be Solved by the Invention) In the conventional device described above, the capacity can be controlled in two stages: an unload operation in which low pressure gas is introduced into the working chamber 16, and a full low-F operation in which high pressure gas is introduced into the working chamber 16. However, the capacity could not be controlled steplessly, that is, continuously.

(Means for Solving the Problems) The present invention was invented to solve the above problems, and its gist is to fit an unloader piston into an unloader cylinder in a sealed and slidable manner. By doing this, the unloader piston is moved by changing the pressure of the working gas by limiting a chamber communicating with the compression chamber on one side of the unloader screw and limiting a working chamber into which the working gas is introduced on the other side. In a capacity control device for a gas compressor that controls the capacity by changing the clearance volume J, depending on the flow of gas, the outlet of a constant pressure valve maintains the pressure at the outlet constant regardless of the gas pressure at the inlet. A capacity control device for a gas compressor is characterized in that the constant pressure valve is connected to the gas suction side of the compressor, and the inlet of the constant pressure valve is connected to the working chamber.

(Function) Since the present invention has the above configuration, when the suction pressure of the compressor decreases, the opening degree of the constant pressure valve increases and a large amount of gas in the working chamber flows to the suction side. As the pressure decreases, the unloader piston
and the top clearance volume increases. Conversely, when the suction pressure of the compressor increases, the opening degree of the constant pressure valve decreases, so the unloader piston descends and the top clearance volume decreases.

(Example) One embodiment of the invention is shown in FIGS. 1 and 2.

Reference numeral 30 denotes a constant pressure valve, the outlet of which is connected to a low pressure gas pipe 27 communicating with the gas inlet of the compressor, and its output is communicated with the working chamber 6 via the pressure piping 5. The working chamber 16 communicates with the discharge chamber 8 through a small hole 29 formed in the cover 20.

Note that the same members as those shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

The details of the constant pressure valve 30 are shown in FIG. 2, and the gas flowing in from the inlet 131 passes through the valve portion 32 and flows out from the outlet 33.

The pressure of the gas flowing out from the outlet 33 is applied to the heros 34 , and the valve opening degree is determined by the balance between the force due to this gas pressure and the force exerted by the adjustment spring 35 . It is designed to maintain a constant pressure. Note that the angle of the adjusting spring 35 can be adjusted by adjusting the adjusting bolt 36.

When the suction pressure of the compressor decreases, such as when the capacity of the compressor is greater than the load, the opening degree of the constant pressure valve 30 increases in order to maintain the pressure at its outlet 33 constant. When the opening degree increases, a large amount of gas in the working chamber 16 flows to the suction port via the constant pressure valve 30, and the pressure in the working chamber 16 decreases. As a result, the pressure in the working chamber 16 becomes lower than the cylinder average pressure introduced into the chamber 19, so the unloader piston 10 rises, the top clearance volume increases, and the capacity of the compressor decreases. When the capacity of the compressor decreases, its suction pressure increases, so the suction pressure is kept constant.

Conversely, when the suction pressure of the compressor increases, such as when the capacity of the compressor is small compared to the load, the opening degree of the constant pressure valve 30 decreases and the pressure within the working chamber 16 increases. As a result, the unloader piston 10 descends and the top clearance volume decreases, increasing the capacity of the compressor. As a result,
Since the suction pressure of the compressor decreases, the suction pressure remains constant.

(Effects of the Invention) In the present invention, the outlet of the constant pressure valve that maintains the pressure at the outlet constant regardless of the gas pressure at the inlet is communicated with the gas suction side of the compressor, and the inlet of the constant pressure valve is activated. Since it communicates with the chamber, it is possible to change the capacity of the compressor steplessly and continuously, and the structure is extremely simple, and a commercially available constant pressure valve can be used as is, so it can be manufactured at low cost.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, with FIG. 1 being a longitudinal sectional view and FIG. 2 being a longitudinal sectional view of a constant pressure valve. FIG. 3 is a longitudinal sectional view of a conventional device.

Claims (1)

[Claims] By fitting the unloader piston in a sealed and slidable manner in the unloader cylinder, one side of the unloader piston limits a chamber communicating with a compression chamber, and the other side limits a working chamber into which working gas is introduced, and the above-mentioned operation In a gas compressor capacity control device that controls the capacity by changing the top clearance volume by changing the gas pressure and moving the unloader piston, the outlet pressure is kept constant regardless of the gas pressure at the inlet. A capacity control device for a gas compressor, characterized in that an outlet of a constant pressure valve to be maintained is communicated with the gas suction side of the compressor, and an inlet of the constant pressure valve is communicated with the working chamber.