JPS5815793A - No-load operation control device of compressor - Google Patents

Abstract

PURPOSE:To make it possible to previously and cerfaimly prevent the generation of surging by detecting air vibration generated just before a substantial surging generation and operating a compressor with no-load. CONSTITUTION:A compressor comes to rush in a surging region when a compressor reaches a region difficult to be controlled under a constant pressure because of reduction of compressed air quantity consumed by a load equipment, being accompanied by the reduction of air flow Q. Immediately before this rush into the surging region, a controller 7b detects presurge via a sensor part 7a provided on the discharge opening 14 of the compressor 1, and provides an actuatin signal for closing a suction valve 4 to a suction valve driver 5. And it simultaneously provides an actuation signal for opening a blowoff valve 12 to a blowoff valve driver 13, whereby the suction valve 4 closes, and the blowoff valve 12 opens to provide a no-load operation, making it possible to previously prevent the generation of surging.

Description

[Detailed Description of the Invention] In particular, by detecting air vibrations that occur immediately before surging and setting the compressor to no-load operation, the occurrence of surging can be reliably prevented. It relates to an operation control device.

One way to prevent surging is to close the suction valve on the suction side of the compressor and open the blow-off valve on the discharge side to release pressurized air to the atmosphere, thereby operating the compressor without load. There are known ways to do this. This method has the advantage that the power consumption of the compressor during low-pressure air consumption can be reduced as much as possible since the back pressure against the compressor is reduced.

By the way, in the above-mentioned no-load operation, as the pressure air consumption of the load equipment connected to the discharge side decreases, the suction air volume on the suction side decreases and the pressure of the pressurized air in the discharge side pipe increases, resulting in surging. Therefore, it is necessary to prevent this from occurring, and it is desirable to prevent this from occurring before entering the surging area. In this case, it may be possible to input the surging area into the computer in advance and automatically perform no-load operation, but the surging area changes variously depending on changes in suction pressure depending on the opening degree of the suction valve. Therefore, it is necessary to input the suction pressure, which complicates the operation and increases costs.

As a result of intensive research, the inventor of the present invention obtained the knowledge that minute vibrations (presurge) of air occurs at the compressor discharge port before entering the above-mentioned surging region, and detected this presurge to enable no-load operation. The present inventors have discovered that the occurrence of surging can be known very easily and reliably and can be prevented from occurring by using the following methods, and have thus completed the present invention. Compressor capacity control method and device capable of preventing the occurrence of surging by detecting the immediately preceding surging from the discharge flow rate (Japanese Patent Laid-Open No. 53-11
No. 3306), but the present invention further simplifies it.

The present invention provides a no-load operation control device for a compressor that can prevent the occurrence of surging with a simple configuration and that can easily perform capacity control that combines constant pressure control and load-no-load control. The purpose is to provide.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, a suction filter 3 for removing dust, etc. from the air being sucked is provided at the inlet of the suction side pipe line 2 of the compressor 1, and between the suction filter 3 and the compressor 1. A suction valve 4 for adjusting the amount of intake air to the compressor 1 is provided in the suction side conduit 2 . This suction valve 4 is provided with a suction valve driver 5 that uses fluid pressure or an electric motor as a driving source to open and close the suction valve. ．． It is configured to be opened and closed by an activation signal from the air vibration detection means 7 or the pressure switch 8.

Specifically, the suction valve driver 5 continuously opens and closes the suction valve 4 in response to the actuation signal from the air pressure regulator 6, and in this state [here, the actuation signal from the air vibration detection means 7 is detected]. When the pressure switch 8 receives an actuation signal from the pressure switch 8, the suction valve 4 is preferentially fully closed, and when an actuation signal from the pressure switch 8 is received in this fully closed state, the suction valve 4 is fully opened.

On the other hand, a pressure detection pipe 10 guided through a pressure regulator 61 is connected to the discharge side pipe 9 of the compressor 1 in order to detect the pressure of the air in this pipe 9. An air vent pipe 11 is connected to release the pressurized air inside 9 to the atmosphere.

The pressure regulator 6 is equipped with a pressure setting device (not shown), and the desired discharge pressure PO determined by this setting device and the actual discharge pressure P obtained via the pressure detection tube 10 are connected to a flapper mechanism or the like. After the deviation is subjected to appropriate arithmetic processing such as proportional or integral processing, an actuation signal necessary to correct the deviation is transmitted to the suction valve driver 5ζ.

The air exhaust pipe 11 is provided with an air discharge valve 12 for opening and closing the air exhaust pipe 11, and the air exhaust valve 12 has a driving means for opening and closing it in response to an operating signal from the air vibration detection means 7 or the pressure switch 6. A discharge valve driver 13 similar to the suction valve driver 5 described above. is provided. This discharge valve driver 1
3 normally holds the blowoff valve 12 in a closed state, and when it receives an activation signal from the air vibration detection means 7, the blowoff valve 12 closes.
is fully opened, and in this fully open state, when an activation signal from the pressure switch 8 is received, the blowoff valve 12 is closed.

By the way, the air vibration detection means 7 detects the air vibration (presurge) that occurs immediately before the occurrence of surging in the compressor 1, and includes a sensor section 7a that picks up air vibrations, and a detection signal from this sensor section 7a to detect the air vibration immediately before the occurrence of surging. a control section 7b that simultaneously detects that the suction valve driver 5 and the discharge valve driver 13 are in the same position and simultaneously provides an operating signal to the suction valve driver 5 and the discharge valve driver 13;
The sensor section 7a is provided facing into the discharge port 14 of the compressor 1, as shown in FIG. In addition, in Figure 2, 1
5, the suction port 16 of the compressor 1 is an impeller. This detection means 7 is configured such that, for example, a strain gauge is embedded in the sensor section 7a, and the strain caused by the resonance of the sensor section 7a that resonates with air vibration is extracted as a voltage change, and this voltage change is further extracted as a pulse proportional to the air frequency. It consists of a so-called pulse detection sensor that controls the presurge frequency in advance by a control unit 7b.
By storing the vibration frequency in the memory, when the frequency is detected, a closing operation signal is given to the suction valve driver 5, and an opening operation signal is given to the discharge valve driver 13.

Further, a receiver tank 18 is connected to the discharge side conduit 9 on the downstream side of the vent pipe 11 via a check valve 17, and a load device is connected to the downstream side of the receiver tank 18. The receiver tank 18 is provided with a pressure switch 8 that detects the pressure of the air accumulated inside, and this pressure switch 8 switches the compressor 1 into load operation when the pressure inside the receiver tank 18 falls below the set pressure. It is configured to give an open actuation signal to the intake valve driver 5 and a close actuation signal to the discharge valve driver 13, respectively.

Next, based on the above configuration, constant pressure control plus load no-load control will be implemented (we will discuss the details).

Now, it is assumed that the pressure regulator 6 is set to the desired ejection pressure po, and the pressure switch 8 is also set to a lower set pressure Pn to enter the constant pressure control operating state. Tf, in other words, constant pressure control is performed to automatically adjust the intake air volume Q according to the pressure air consumption of the load equipment in order to maintain the desired ejection pressure PO at a constant value.In this case, the operation shown in Fig. 3 Point A and B on the control curve
Control is performed between the points. In this state, the pressure air consumption of the load equipment decreases, and the intake air volume Q decreases accordingly, reaching a range where constant pressure control is no longer possible, and eventually entering the surging region. Just before entering this surging region, the controller 7b detects the presurge via the sensor section γa provided at the discharge port 14 of the compressor 1, and gives an actuation signal to the suction valve driver 5 to close the suction valve 4. At the same time, the blow-off valve driver 13 (the blow-off valve driver 13) gives an actuation signal to open the blow-off valve 12, thereby closing the suction valve 4 and opening the blow-off valve 12, resulting in no-load operation. In the figure, no-load operation occurs at point B, and the discharge pressure P and intake air flow Q decrease to point 6.While this no-load operation continues, the pressure inside the receiver tank 18 decreases due to the consumption of pressure air from the load equipment, and the pressure in the receiver tank 18 decreases to the set point. When the pressure falls below Pn, the pressure switch 8 is activated, and an actuation signal is issued to the suction valve driver 5 to open the suction valve [15], and an actuation signal to the discharge valve driver 13 to close the discharge valve 12. Machine 1 is shown in Figure 3 (
The load operation indicated by the 0 point begins. Due to this load operation, the pressure in the discharge 1llllj pipe 9 increases to the desired output pressure PO.
When the pressure is reached, the compressor 1 shifts to the constant pressure control operation as described above.

Note that in a state where constant pressure control is being performed, if the pressure air consumption of the load equipment increases and the pressure in the receiver tank 18 becomes less than the set pressure Pn, the pressure switch 8 works to switch to load operation. In this case, since the blowoff valve 12 is already in a closed state, only the suction valve 4 is fully opened.

Therefore, the combined capacity control of constant pressure control plus load-no-load control can be carried out extremely easily and reliably. Note that the sensor section 7a of the air vibration detection means 7 may be configured by a microphone.

In summary, the present invention exhibits the following excellent effects.

(1) By detecting the air vibrations that occur just before surging occurs, the compressor is put into no-load operation, so surging can be effectively prevented from occurring even though the configuration is extremely simple. can do.

(2) Since it is extremely easy to shift to no-load operation, capacity control that combines constant pressure control and load-no-load control can be easily implemented by using attached equipment such as pressure regulators and pressure switches. be able to.

(3) In addition, the above-mentioned no-load operation is performed by completely shutting off the intake air and releasing the discharge pressure air to the atmosphere. Consumption can be reduced as much as possible.

[Brief explanation of drawings]

Fig. 1 is a control system diagram showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of main parts showing a state in which the compressor is provided with a detection means,
FIG. 3 is a graph showing the relationship between the discharge pressure and the intake air volume to explain the operation control situation. In the figure, 1 is a compressor, 4 is a suction valve, 5 is its driving means, 7
12 is a blowoff valve, 13 is a driving means thereof, and 14 is a discharge port of the compressor.

Claims (1)

[Claims] ■ In a device that controls no-load operation by providing a suction valve on the suction side of the compressor and a blowoff valve on the discharge side to release pressurized air to the atmosphere, closing the suction side and opening the discharge side during surging. A compression compressor characterized in that the discharge port is provided with a detection means for detecting air vibrations that occur immediately before surging occurs, and a drive means is provided that closes the suction valve and opens the discharge valve based on the detection signal t obtained from the detection means. Machine no-load operation control device.