JPH0617014Y2 - Compressor capacity control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a capacity control device for an air compressor, and more specifically, the compressed air in the compressor completes discharge even when the compressor is stopped. Until then, the present invention relates to a compressor capacity control device capable of reliably closing the unloader valve.

(Prior Art) Conventionally, a capacity control device for a rotary compressor has an unloader device 2 provided in a suction portion of a compressor body 1 as shown in FIG.
According to the pressure in the receiver tank 3 to open and close the solenoid valve sv1 via an electric control circuit (not shown) to introduce the tank pressure into the primary chamber 4 of the unloader device, and to adjoin the primary chamber. 2 to 3 kgf / cm ₂ of decompressed air is constantly introduced into the secondary chamber 9 through the decompression valve 8 during operation of the compressor, and the diaphragm 5 is moved to the diaphragm 5 by the balance with the compressed air pressure introduced into the primary chamber. It is configured to press the fixed unloader piston 6 to control opening / closing of the unloader valve 7.

Further, the receiver tank is provided with a pipe connected to the auto relief valve 10 through a three-way solenoid valve sv2, and when the compressor is stopped, the three-way solenoid valve is opened to open the auto relief valve 10 to open the inside of the receiver tank. It is designed to direct compressed air to the outside.

(Problems to be Solved by the Invention) In the above-described conventional machine, the pressure in the primary chamber 4 is gradually reduced as the auto relief valve is discharged when the compressor is stopped.

Then, when the pressure in the primary chamber becomes equal to or less than the set pressure value in the secondary chamber 9 of 2 to 3 kgf / cm ₂ , the unillustrated valve in the pressure reducing valve 8 is in the closed state, and thus the secondary chamber The unloader valve 7 is opened when the indoor pressure temporarily exceeds the internal pressure of the primary chamber 4.

As a result, the compressed air in the airtight mixed state, which has flowed back into the intake chamber 11 with the stop of the compressor, is released.
Flowing out to the suction port 13 via a suction pipe 14 connected to the suction port, the element in the air cleaner 15 is soiled with oil to promote clogging of the element,
It has a problem of shortening the life.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an auto-relief valve that automatically discharges compressed air in a receiver tank to the atmosphere when the compressor is stopped, a receiver tank, and a receiver tank. It has a primary chamber and a receiver tank that are connected by piping via a solenoid valve that opens and closes according to pressure, and a secondary chamber that is connected by piping through a pressure reducing valve, and the compressed air pressure introduced into the primary chamber and the above In a compressor capacity control device equipped with an unloader device for controlling an intake air amount by moving an unloader piston by opening and closing an unloader valve according to the balance of the depressurized air pressure in the secondary chamber, at the same time as stopping the compressor, It is characterized in that an air release system passage for automatically releasing the depressurized air pressure in the secondary chamber to the atmosphere is provided.

(Examples) The details of the present invention will be described below with reference to FIGS. 1 and 4.

The same members as those in the conventional example will be described using the same reference numerals.

Between the primary chamber 4 of the unloader device 2 and the receiver tank 3,
The solenoid valves sv1 are connected to each other through the pipes 21 and 22 via the solenoid valve sv1, and the solenoid valve sv1 is located on the A side until the pressure in the receiver tank 3 reaches the specified pressure during the operation of the compressor. When the value exceeds the specified value (7 kgf / cm ₂ ), the signal from the pressure switch PS is received and the position is switched to the position B shown.

On the other hand, the secondary chamber 9 has a pipe 2 communicating with the receiver tank 3.
1 and the reduced pressure air reduced in pressure by the pressure reducing valve 8 to about ₂ to 3 kgf / cm ₂ is introduced, and the check valve 24 is branched from the pressure reducing pipe 23 corresponding to the secondary side of the pressure reducing valve 8. A pipe 25, which communicates with the port e of the three-way solenoid valve sv2 through the pipe 25, is provided as a discharge system passage.

Further, a pipe 27 communicating with the drain tank 26 is branched to the pipe 21, and below the drain tank 26,
An auto relief valve (compressed air automatic discharge valve) 10 is mounted.

Then, from the drain tank 26, the pilot pipe 28
Is connected to the port d of the three-way solenoid valve sv2 via the check valve 30, and the closed port chamber 35 of the auto relief valve 10 from the other port e via the pilot pipe 29 (Fig. 4).
Connected to.

During operation of the compressor, the three-way solenoid valve sv2 is always located on the C side, whereby the compressed air in the drain tank 26 communicates with the closed valve chamber 35 of the auto relief valve 10 via the pipes 28 and 29, and the diaphragm. 36 is pushed upward in the drawing to close the vent hole 38 of the valve 37, and the communication of the vent hole 38 to the atmosphere is maintained in a closed state.

Next, the operation of the device of the present invention will be described.

When the compressor starts and enters the full load state, the solenoid valve sv1 is located on the A side, from which the receiver tank 3 and the unloader device 2
The primary chamber 4 is closed, and the primary chamber 4 is the intake chamber 1 of the compressor.
1 to receive negative pressure in the intake chamber 11. On the other hand, inside the secondary chamber 9 adjacent to the diaphragm 5 via the diaphragm 5,
The compressed air of ₂ to 3 kgf / cm ₂ that has been decompressed by is fed, the unloader piston 6 moves to the right in the figure, and the unloader valve 7 is opened, and the full load state is maintained in this state.

Next, when the air consumption on the consumer side decreases, the pressure in the receiver tank 3 exceeds the specified pressure (7 kgf / cm ₂ ). Then, the solenoid valve sv1 receives the signal from the pressure switch PS and switches to the B side, whereby the high-pressure compressed air in the receiver tank 3 is introduced into the primary chamber 4. Therefore, the unloader piston 6 moves to the left side in the figure, the valve seat 12 of the unloader valve 7 is closed, and in this state, the compressor is in a no-load operation state.

In this state, when the compressor is stopped by a stop switch of an electric circuit (not shown), the solenoid valve sv1 maintains the position B as it is, while the three-way solenoid valve sv2 switches to the D side,
The communication between the drain tank 26 and the valve closing chamber 35 of the auto relief valve 10 is cut off, and the pressure in the pipe 29 is released from the port e to the atmosphere via the port f.

As a result, the diaphragm 36 of the auto relief valve 10 is pushed downward by the pressure in the drain tank 26, and the vent hole 38 is opened to connect the inside of the drain tank 26 and the atmosphere. Therefore, the receiver tank 3
The compressed air in the inside passes through the pipes 21 and 27 and the drain tank 26, and is discharged to the atmosphere through the vent hole 38 of the auto relief valve 10.

On the other hand, the pressure in the primary chamber 4 of the unloader device 2 also gradually decreases with the release operation of the pressure in the receiver tank,
As a result, the depressurized air in the secondary chamber 9 first passes through the port 25 of the solenoid valve sv2 through the pipe 25 serving as an air discharge system path to the atmosphere and the pilot pipe 29 together with the pressure in the pilot pipe 29 to quickly become the atmosphere. As it is released, the unloader piston 6
Is pressed in the closing direction of the unloader valve by the compressed air pressure in the primary chamber 4 until the internal pressure of the receiver tank is completely released into the atmosphere by the auto relief valve 10.
The valve seat 12 can be surely kept closed.

Therefore, with the conventional release of the receiver tank internal pressure, backflow air enters the air cleaner 15 through the valve seat 12 through the intake port 13 and soaks the air cleaner element with oil to promote clogging or shorten the life. The problem is solved.

It should be noted that in the above-described embodiment, the unloader device 2 has two components.
Although the pipe 25 as an air discharge passage communicating with the next chamber 9 is configured to be connected to the port e of the three-way solenoid valve sv2, the secondary pipe 23 of the pressure reducing valve 8 is reversely connected as shown in FIG. Stop valve 24
Even if the air discharge system path is configured so as to communicate with the drain tank 26 by the pipe 25 'via the same, the same operation is achieved.

(Effects of the Invention) As described above, the present invention simply adds a simple configuration to the piping system of the conventional capacity control device, and the release of the receiver tank internal pressure is completed by the auto-relief valve when the compressor is stopped. Since the unloader valve can be continuously closed during this period, oil stains on the air cleaner element due to backflow of compressed air from the suction port can be prevented, and a good condition can be maintained.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 2 is a detailed view of a main part of another embodiment, FIG. 3 is a detailed view of a conventional device, and FIG. 4 is a detailed view of an auto relief valve. . 2 …… Unloader device 3 …… Receiver tank 4 …… Primary chamber 7 …… Unloader valve 8 …… Decompression valve 9 …… Secondary chamber 24 …… Check valve

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An automatic relief valve that automatically discharges compressed air in a receiver tank to the atmosphere when the compressor is stopped, and a receiver tank and a solenoid valve that opens and closes according to the pressure of the receiver tank. Chamber and receiver tank, and a secondary chamber connected by piping via a pressure reducing valve. The unloader piston is moved by the balance between the compressed air pressure introduced into the primary chamber and the reduced pressure air pressure in the secondary chamber. In a capacity control device for a compressor equipped with an unloader device that opens and closes an unloader valve to control the intake air amount, an air release system that automatically releases the depressurized air pressure in the secondary chamber of the unloader device to the atmosphere at the same time when the compressor is stopped. A compressor capacity control device characterized in that a passage is provided.