JP2006283649A - Compressor and its operation control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compressor in which a discharge pressure can be maintained in a desired pressure range without reducing the compression efficiency to the load variation. <P>SOLUTION: The oil-cooled compressor is provided with a compressor main body 20 having a suction adjusting valve 21 and compressing the gas sucked from a suction passage 28 to allow a certain quantity or less of the gas to pass even when the suction adjusting valve 21 is totally closed, a relief valve 25 installed in a relief passage 35 connected to a discharge passage 29 of the compressor main body 20, a pressure detection means 27 to detect a discharge pressure P installed in the gas supply side than a check valve 26 of the discharge passage 29, and a controller 30 to make the discharge pressure P fall in the range of an upper limit pressure P<SB>H</SB>to a lower limit pressure P<SB>L</SB>. The controller 30 has a function, corresponding to the discharge pressure P, to perform A operation control and B operation control to control the suction adjusting valve 21 and the air relief valve 25 to the set opening and closing state respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of a compressor and its operation control method, and more particularly to a compressor and an operation control method thereof that can appropriately cope with load fluctuations.

  In a compressor provided with a suction adjustment valve on the suction side of the compressor body and provided with a discharge valve on the discharge side, conventionally, when the pressure on the discharge side becomes high, the suction adjustment valve is closed, and the discharge valve is opened. On the contrary, when the pressure on the discharge side becomes low, the suction adjustment valve is opened, and the discharge capacity is adjusted by the load / unload control operation in which the discharge valve is closed. However, this operation method has the disadvantage that the compressed gas produced with great effort is discharged to the atmosphere via the air release valve during unloading, so that the operation efficiency is poor.

  Therefore, a conventional compressor operation method (see Patent Document 1) proposed to solve the above-described drawback will be described below with reference to FIG. This screw compressor includes a PI control device 6, a pressure control valve 1 on the suction side of the compressor body 2, and a pressure sensor 5 provided on the discharge side of the compressor body 2 so that pressure can be detected. A capacity control system including a regulating valve 11 and an inverter 7 is provided.

  And according to the said operating method, when the pressure detected by the said pressure sensor 5 becomes high, the rotation speed of the motor 8 will be reduced via the said PI control apparatus 6 and the inverter 7, and when the said pressure becomes low, conversely, The capacity control for keeping the pressure constant is performed by the rotational speed control for increasing the rotational speed of the motor 8. However, when the rotational speed of the motor 8 is lowered and the inverter 7 is about to trip due to overload, the rotational speed control using the inverter 7 and the PI control device 6 is stopped, and the pressure is maintained by adjusting the intake air. Switch to control. That is, the pressure regulating valve 11 is opened, the opening degree of the suction regulating valve 1 is reduced when the pressure is increased, and the opening degree is increased when the pressure is lowered.

However, according to the operation method of the compressor according to the conventional example, when the pressure on the discharge side increases, the rotational speed of the motor is decreased until just before the inverter trips. For this reason, this rotational speed may decrease too much. In this case, the amount of leakage of the gas compressed in the screw compressor main body to the suction side increases, resulting in a problem that the compression efficiency decreases. This increase in the amount of leakage occurs in the case of an oil-free screw compressor that is not oil-sealed compared to an oil-sealed screw compressor in which the gap between the screw rotors and the gap between the screw rotor and the rotor chamber wall is oil-sealed. , Especially noticeable. Further, there is a problem that an abnormal temperature rise occurs on the discharge side as the leakage amount increases.
Japanese Patent Laid-Open No. 6-10876

  Accordingly, an object of the present invention is to provide a compressor capable of maintaining a discharge pressure in a desired pressure range without reducing the compression efficiency with respect to load fluctuations, and an operation control method thereof.

In order to achieve the above object, the means employed by the compressor according to claim 1 of the present invention is provided with a suction adjustment valve, and allows passage of a certain amount of gas or less even when the suction adjustment valve is fully closed. A compressor main body for compressing the gas sucked from the suction flow path, a discharge flow path having one end connected to a discharge port of the compressor main body, branched from the discharge flow path and passed through the discharge flow path The discharge pressure of the gas supplied to the gas supply destination from the branch point to the discharge flow path of the discharge flow path is provided in the discharge flow path for releasing a part of the compressed gas In the compressor provided with a pressure detection means for detecting P, and having a controller for opening and closing the suction adjustment valve and the discharge valve, the controller includes a lower limit set pressure P _L therein, a first intermediate set pressure Psa made larger than the lower limit set pressure P _L, the A second intermediate set pressure Psb made larger than the limit set pressure P _L, the first intermediate set pressure Psa, and a large becomes the upper limit set pressure P _H than either of the second intermediate set pressure Psb preset, the discharge pressure P Decreases to the lower limit set pressure P _L , the load adjustment operation is performed to open the suction adjustment valve and close the discharge valve. When the discharge pressure P increases and reaches the first intermediate set pressure Psa, the suction is performed. while performing a driving control to an intermediate load operation of closing the closing vital Hokiben adjustment valve, and reaches the upper limit set pressure P _H discharge pressure P rises, closes the suction adjustment valve vital The unload operation is performed to open the air release valve, and when the discharge pressure P decreases and reaches the second intermediate set pressure Psb, it has a function of performing B operation control as the intermediate load operation. Is.

The means employed by the compressor according to claim 2 of the present invention is the compressor according to claim 1,
During the intermediate load operation in the A operation control, the controller switches to the B operation control when the discharge pressure P becomes higher than the first intermediate set pressure Psa, while the intermediate load operation in the B operation control When the discharge pressure P becomes lower than the second intermediate set pressure Psb, a function of switching to the A operation control is provided.

  The compressor employed in the compressor according to claim 3 of the present invention is the compressor according to claim 1, wherein the discharge pressure P is set to the first intermediate during the intermediate load operation in the A operation control. When the pressure is higher than the set pressure Psa by a predetermined pressure ΔPsa, the operation is switched to the B operation control. On the other hand, during the intermediate load operation in the B operation control, the discharge pressure P is only the predetermined pressure ΔPsb from the second intermediate set pressure Psb. When the pressure becomes lower than the low pressure value, it has a function of switching to A operation control.

  The means employed by the compressor according to claim 4 of the present invention is the compressor according to any one of claims 1 to 3, wherein the controller is in an unload operation in the B operation control. When the duration exceeds a predetermined time, a function for stopping the operation of the compressor body is provided.

  The means employed by the compressor according to claim 5 of the present invention is the compressor according to any one of claims 1 to 4, wherein the controller is in the middle load operation in the A operation control. When the duration exceeds a predetermined time, a function for switching to the road operation is provided.

  The means employed by the compressor according to claim 6 of the present invention is the compressor according to any one of claims 1 to 5, wherein the first intermediate set pressure Psa and the second intermediate set pressure are used. Psb has the same value.

The means adopted by the compressor operation control method according to claim 7 of the present invention is a suction flow path that is provided with a suction adjustment valve and allows passage of a certain amount or less of gas even when the suction adjustment valve is fully closed. A compressor main body for compressing the gas sucked from the compressor, and a discharge flow path having one end connected to a discharge port of the compressor main body. The compressed gas that branches from the discharge flow path and passes through the discharge flow path An air release valve is provided in the air release flow path for releasing a part, and the discharge pressure P of the gas supplied to the gas supply destination is detected from the branch point of the discharge flow path to the air discharge flow path to the gas supply destination side. in the operation control method of a compressor comprising a pressure detecting means is provided, and the lower limit set pressure P _L, a first intermediate set pressure Psa made larger than the lower limit set pressure P _L, made larger than the lower limit set pressure P _L first 2 intermediate set pressure Psb and the first intermediate set pressure Psa, second intermediate Set is large becomes an upper limit set pressure P _H and a preset than any pressure Psb, in response to the discharge pressure P, it is characterized in that to perform any of the operation control described below.
・ When the discharge pressure P decreases and reaches the lower limit set pressure P _L , load operation is performed to open the suction adjustment valve and close the discharge valve, and the discharge pressure rises to the first intermediate set pressure Psa. If, it reaches the upper limit set pressure P _H a operation control, the discharge pressure P of the intermediate load operation to close the valve closing vital Hokiben suction adjustment valve rises, closes the suction adjustment valve vital The unload operation is performed to open the release valve, and the discharge pressure P decreases to reach the second intermediate set pressure Psb.
Then, the B operation control for the intermediate load operation

  The means adopted by the compressor operation control method according to claim 8 of the present invention is the compressor operation control method according to claim 7, wherein the discharge pressure P is set during the intermediate load operation in the A operation control. When the pressure is higher than the first intermediate set pressure Psa, the operation is switched to the B operation control. On the other hand, when the discharge pressure P is lower than the second intermediate set pressure Psb during the intermediate load operation in the B operation control, the operation is switched to the A operation control. It is characterized by this.

  The means adopted by the compressor operation control method according to claim 9 of the present invention is the compressor operation control method according to claim 7, wherein the discharge pressure P is set during the intermediate load operation in the A operation control. When the pressure becomes higher than a pressure value higher than the first intermediate set pressure Psa by a predetermined pressure ΔPsa, the operation is switched to the B operation control. On the other hand, during the intermediate load operation in the B operation control, the discharge pressure P is set higher than the second intermediate set pressure Psb. When the pressure becomes lower than the pressure value lower by the pressure ΔPsb, the operation control is switched to the A operation control.

  The means adopted by the compressor operation control method according to claim 10 of the present invention is the compressor operation control method according to any one of claims 7 to 9, wherein the B operation control is performed. When the duration during the unload operation exceeds a predetermined time, the operation of the compressor body is stopped.

  The means adopted by the compressor operation control method according to claim 11 of the present invention is the compressor operation control method according to any one of claims 7 to 10, wherein the A operation control is performed. When the duration during the intermediate load operation exceeds a predetermined time, the operation is switched to the load operation.

  The means adopted by the compressor operation control method according to claim 12 of the present invention is the compressor operation control method according to any one of claims 7 to 11, wherein the first intermediate setting is performed. The pressure Psa and the second intermediate set pressure Psb are the same value.

According to the compressor and the operation control method thereof according to claims 1 and 7 of the present invention, the discharge pressure is set within a desired pressure range (between the upper limit set pressure P _H and the lower limit set pressure P _L) regardless of load fluctuations. Range) can be maintained properly without reducing the compression efficiency. In addition, the air release valve is not opened except during the unload operation of the B operation control, and the amount of the produced compressed gas to be released can be minimized, so that the operation efficiency can be improved.

  Further, according to the compressor and the operation control method thereof according to claims 2, 3, 8, and 9 of the present invention, the further increase in the discharge pressure P can be caused by the B operation in which the release valve can be opened by the unload operation. It can be avoided by switching to control. On the other hand, since it is not possible to expect an increase in the discharge pressure P at a flow rate less than a certain amount allowed from the suction flow path, the suction adjustment valve is opened by switching to the A operation control capable of the load operation and the discharge pressure is increased. P can be boosted. As a result, the effect of appropriately maintaining the discharge pressure in a desired pressure range can be further ensured without lowering the compression efficiency regardless of load fluctuations.

  Furthermore, according to the compressor and the operation control method thereof according to claims 4 and 10 of the present invention, conventionally, the drive that operated the compressor body despite the fact that the consumption of compressed gas is none or minimal. Power loss can be reduced.

  Further, according to the compressor and the operation control method thereof according to claims 5 and 11 of the present invention, since the ratio of the efficient load operation can be increased, it is possible to realize the efficient operation as a whole.

  Furthermore, according to the compressor and the operation control method thereof according to claims 6 and 12 of the present invention, the first intermediate set pressure Psa and the second intermediate set pressure Psb are set to the same value, thereby setting each value. Can reduce the load.

  First, a configuration of a compressor according to an embodiment of the present invention will be described with reference to FIG. 1 of the accompanying drawings. FIG. 1 is a system diagram of a compressor according to an embodiment of the present invention, and more specifically, a system diagram when the present invention is applied to an oil-cooled compressor. This oil-cooled compressor (hereinafter referred to as a compressor) includes a compressor main body 20 having a structure in which a pair of male and female screw rotors (not shown) mesh with each other and are rotatably accommodated inside a rotor casing. Yes.

A suction flow path 28 is connected to the suction port 20a of the compressor body 20, and a discharge flow path 29 is connected to the discharge port 20b. One of the pair of male and female screw rotors constituting the compressor body 20 (usually a male rotor) is connected to a motor 22.
By rotating the screw rotor by the motor 22, the gas supplied from the suction flow path 28 is compressed by the compressor body 20 and discharged to the discharge flow path 29 as a high-pressure fluid.

  The suction flow path 28 is provided with a suction adjustment valve 21 that adjusts the flow rate of the gas passing through the suction flow path 28. In addition, a bypass passage 36 is provided in which the upstream side and the downstream side of the suction adjustment valve 21 of the suction passage 28 are directly connected, and the suction adjustment valve 21 is fully closed when the compressor is operating. In addition, an orifice 37, which is a quantitative intake means capable of continuing to suck a predetermined amount or less into the compressor body 20 and discharging a low-volume compressed gas, is interposed in the bypass flow path 36. As another alternative means for this fixed quantity intake means, a throttle mechanism such as a nozzle or a venturi can be cited. Further, the intake flow rate by the fixed intake means such as the orifice 37 is 5 to 30%, preferably 10 to 20%, of the produced compressed gas flow rate.

  The discharge passage 29 includes an oil separator 24 for capturing the lubricating oil mixed in the compressed gas, and an oil recovery unit 23 including an oil sump 31 for collecting and storing the captured lubricating oil. It is intervened. Lubricating oil in the oil sump 31 is supplied via the oil flow path 32 to locations requiring supply of lubricating oil, such as bearings and shaft seals inside the compressor body 20 and a compression space formed by the rotor and rotor casing. Is done. The oil flow path 32 is provided with an oil filter 33 that filters and cleans the lubricating oil, and an oil cooler 34 that cools the oil.

  Further, a check valve 26 is provided in the discharge passage 29 downstream from the oil separator 24. The discharge passage 29 between the oil separator 24 and the check valve 26 branches off from the discharge passage 35 communicating with the atmosphere, and the discharge passage 35 is provided with the discharge valve 25. . That is, a part of the compressed gas that passes through the discharge flow path 29 can be released to the atmosphere by the discharge flow path 35.

  Further, the discharge flow path 29 further downstream than the check valve 26, in other words, the discharge flow path 29 on the gas supply destination side from the portion branched to the discharge flow path 35, the compressed gas gas in the flow path is provided. Pressure detection means 27 is provided so that the pressure at the supply destination can be detected. The pressure detection means 27 is a known diaphragm type or transducer type pressure sensor, and transmits a pressure signal corresponding to the detected discharge pressure P of the compressed gas to the controller 30.

Then, the controller 30 controls the suction regulating valve 21 as will be described later so that the discharge pressure P is in a range between an upper limit set pressure P _H having an intermediate set pressure Ps and a lower limit set pressure P _L therebetween. And a function of controlling opening and closing of the air release valve 25. The intermediate set pressure Ps means an intermediate pressure appropriately set between the upper limit set pressure P _H and the lower limit set pressure P _L. The intermediate set pressure Ps, the upper limit set pressure P _H , and the lower limit set pressure P _L are set in advance in an arithmetic circuit in the controller 30.

  In addition, the intermediate set pressure Ps is the first intermediate set pressure Psa and the second intermediate set pressure Psb in the claims of the present invention. That is, here, the first intermediate set pressure Psa and the second intermediate set pressure Psb having the same value are shown as examples.

When the pressure signal detected by the pressure detection means 27 is transmitted to the controller 30, the controller 30 opens the suction adjustment valve 21 and opens the air release valve 25 according to the discharge pressure P. a load operation for closing the suction control valve 21 repeating the intermediate load operation for closing the closing vital Hokiben 25, between the discharge pressure P of the lower limit set pressure P _L and the intermediate set pressure Ps It has a function to perform A operation control to maintain the pressure.

That is, when the discharge pressure P decreases and reaches the lower limit set pressure P _L , the controller 30 performs a load operation that opens the suction adjustment valve 21 and closes the discharge valve 25, and the discharge pressure P increases. When the intermediate set pressure Ps (first intermediate set pressure Psa) is reached, the A operation control is performed so that the suction adjustment valve 21 is closed and the air discharge valve 25 is closed.

At the same time, the controller 30 also closes the suction adjustment valve 21 and opens the air release valve 25 according to the discharge pressure P, and closes the suction adjustment valve 21 and the air release valve. repeating the intermediate load operation of closing the 25, it has both a function for B operation control to be maintained at a pressure between the discharge pressure P intermediate set pressure Ps and the upper limit set pressure P _H.

That is, when the discharge pressure P increases and reaches the upper limit set pressure P _H , the controller 30 performs an unload operation in which the suction adjustment valve 21 is closed and the discharge valve 25 is opened. When the pressure drops and reaches the intermediate set pressure Ps (second intermediate set pressure Psb), the B operation control is performed as an intermediate load operation in which the suction adjustment valve 21 is closed and the air release valve 25 is closed.

Then, by selectively performing the operation control of either the A operation control or the B operation control, the discharge pressure P of the compressor body 20 is set between a predetermined lower limit set pressure P _L and an upper limit set pressure P _H. It is configured to maintain the range.

  Next, a compressor operation control method according to an embodiment of the present invention will be described in detail with reference to FIG. 2 of the accompanying drawings. FIG. 2 is a relationship diagram showing the discharge pressure P and the operating state of the compressor according to the embodiment of the present invention. In FIG. 2, the horizontal axis represents the discharge pressure P detected by the pressure detection means 27, and the vertical axis represents the operating state of the compressor body 20 controlled by opening and closing of the suction adjustment valve 21 and the discharge valve 25. Show.

Suppose now that the compressor is in an A operation control state in which the discharge pressure P is not less than the lower limit set pressure P _{L and} less than the intermediate set pressure Ps, and the suction adjustment valve 21 and the air release valve 25 are fully closed. Suppose that Further, the compressed gas production amount of this compressor is Qo, and the compressed gas consumption amount of the load is Qc.
In the load state of Qc> Qo, the discharge pressure P decreases, and when the preset lower limit set pressure P _L is reached, the suction adjustment valve 21 is fully opened and the release valve 25 is fully closed. The switching discharge pressure P increases.

Further, when the discharge pressure P rises to the intermediate set pressure Ps, the operation state returns to the original intermediate load operation state from the load operation, and the states of the load operation and the intermediate load operation are alternately repeated. Therefore, the discharge pressure P is maintained between the lower limit set pressure P _L and the intermediate set pressure Ps. That is, in this case, the discharge pressure P is maintained in the vicinity of the intermediate set pressure Ps only by opening and closing the suction adjustment valve 21 with the air release valve 25 fully closed.

In addition, when the load operation is performed by the A operation control, the load condition is normally Qc <Qo, and the discharge pressure P increases. Next, even if the pressure becomes equal to or higher than the intermediate set pressure Ps and the load operation is switched to the intermediate load operation, the load state of Qc <Qo is maintained depending on the load state, and the discharge pressure is increased while the discharge valve 25 is not opened. P may rise. Therefore, in this case, the A operation control is switched to the B operation control. Accordingly, the discharge pressure P is not transferred to the unload operation reaches the upper limit set pressure P _H, it is possible to avoid the pressure increase by opening the Hokiben 25.

The necessity of switching from the A operation control to the B operation control is not immediately after the discharge pressure P has reached the intermediate set pressure Ps, but when the predetermined time has elapsed after switching from the load operation to the intermediate load operation. It is desirable to determine whether the pressure P is equal to or higher than the intermediate set pressure Ps. Alternatively, after the load operation is switched to the intermediate load operation, when the pressure value is higher than the intermediate set pressure Ps by a predetermined pressure ΔPsa, the A operation control may be switched to the B operation control. The “pressure value higher than the intermediate set pressure Ps by the predetermined pressure ΔPsa” here is a pressure value lower than the upper limit set pressure P _H.

On the other hand, the intermediate load operation in the B operation control, when the load state of Qc <Qo, the discharge pressure P is gradually increased, but switched to the unloading operation is the upper limit set pressure P _H or more, air release Since the valve 25 is opened, the discharge pressure P decreases. Further, when the discharge pressure reaches the intermediate set pressure Ps, the intermediate load operation and the unload operation are alternately repeated so that the original intermediate load operation is restored. It is maintained at a pressure between Ps and the upper limit set pressure P _H. That is, in this case, the discharge pressure P is maintained in the vicinity of the intermediate set pressure Ps only by opening and closing the air release valve 25 with the suction adjustment valve 21 fully closed.

Further, when the unload operation is performed by the B operation control, the load condition is normally Qc> Qo, and the discharge pressure P decreases. Next, even when the preset intermediate set pressure Ps is reached and the unload operation is switched to the intermediate load operation, the load state of Qc> Qo may be maintained depending on the load condition, and the discharge pressure may further decrease. Therefore, in this case, the B operation control is switched to the A operation control. As a result, the discharge pressure P reaches the lower limit set pressure P _L , and the pressure adjustment can be avoided by opening the suction adjusting valve 21 and shifting to the load operation for intake.

The necessity of switching from the B operation control to the A operation control is not immediately after the discharge pressure P has reached the intermediate set pressure Ps, but when the predetermined time has elapsed after switching from the unload operation to the intermediate load operation. It is desirable to determine whether or not the discharge pressure P is equal to or lower than the intermediate set pressure Ps. Alternatively, after the unload operation is switched to the intermediate load operation, when the pressure value is lower than the intermediate set pressure Ps by a predetermined pressure ΔPsb or less, the B operation control may be switched to the A operation control. The “pressure value lower than the intermediate set pressure Ps by the predetermined pressure ΔPsb” here is a pressure value higher than the lower limit set pressure P _L.

The compressor main body is provided with the controller 30 for controlling the opening and closing of the suction regulating valve 21 and the air release valve 25 and is operated as described above, so that the compressed gas is discharged unnecessarily or unnecessary compression is performed. Without producing gas, the discharge pressure P can be maintained within a certain pressure range P _L ≦ P ≦ P _H around the set pressure Ps. In order to maintain the discharge pressure P within a certain pressure range, it is not essential to change the rotational speed of the motor, which may cause a problem of a decrease in compression efficiency due to an excessive decrease in the rotational speed of the motor. Absent.

Furthermore, during the unload operation in the B operation control, when air consumption Qc of the load becomes very small, the discharge pressure P is switched to the unloading operation becomes elevated limit set pressure P _H or more, induction regulator Even when the valve 21 is closed and the discharge valve 25 is opened, the discharge pressure P does not decrease. In addition to accounting for the duration during this unload operation, a function is added to the controller 22 for stopping the compressor body 20 when the unload operation duration exceeds a preset fixed time. In the above case, it can be determined that there is no or very little air consumption of the load. Therefore, by adding the function to the controller 22, it is possible to reduce the driving power loss of the motor.

Furthermore, in the A operation control, it is preferable to forcibly switch to the unload operation when the duration time of the intermediate load operation exceeds a predetermined time set in advance. From the viewpoint of compressor operation efficiency, road operation is the most efficient. However, in order to select the load operation, it is necessary to be in the state of A operation control. Since either the road operation or the intermediate load operation is adopted for the A operation control, it becomes inefficient when the ratio of the latter exceeds a certain level.
Therefore, as described above, in the A operation control, when the duration of the intermediate load operation exceeds a predetermined time set in advance, the discharge pressure P is decreased by forcibly switching to the unload operation. Switching to road operation is expected to increase the proportion of road operation. Thereby, efficient operation as a whole can be realized.

On the other hand, the condition for stopping the compressor is that the change rate per unit time of the discharge pressure P of the compressor is detected by the pressure detection means 27, and the arithmetic circuit in the control means 30 is stopped for a preset predetermined time or more. However, when it is determined that the discharge pressure P does not become P _L or less, it is preferable to output a stop signal to the motor that drives the compressor body. The predetermined time is preferably about 3 minutes.

As described above, according to the compressor and the operation control method thereof according to the present invention, the suction flow path that is provided with the suction adjustment valve and allows the passage of a certain amount of gas or less even when the suction adjustment valve is fully closed. In the compressor comprising a compressor body for compressing the gas sucked from the air and having a controller for opening and closing the suction adjusting valve and the air release valve, the controller releases the air according to the discharge pressure P. A controller having a function of performing the A operation control and the B operation control defined by the valve opening control of the valve and the suction adjusting valve is provided, and the operation efficiency is not reduced by reducing the compression efficiency against the load fluctuation. In addition, the discharge pressure P can be maintained in a desired pressure range. Further, since the discharge pressure P is prevented from opening the Hokiben except when a predetermined maximum pressure P _H or more, because it is possible to minimize the air release amount, it is possible to improve the efficiency of the operation.

  The present invention is not limited to that described above. For example, as described above, the present invention is preferably applied to an oil-cooled compressor, but is not limited thereto, and may be applied to a compressor other than an oil-cooled compressor. Further, a check valve that allows only the flow toward the compressor body 20 may be interposed in the suction flow path 28 and the bypass flow path 36.

Further, by setting the first intermediate set pressure Psa and the second intermediate set pressure Psb to the same value, the load required to set each value can be reduced. Therefore, both are set to the same intermediate set pressure Ps. As described above. However, the present invention is not limited to this, and the first intermediate set pressure Psa and the second intermediate set pressure Psb may be different values. That is, the first intermediate set pressure Psa is greater than the lower limit set pressure P _L , the second intermediate set pressure Psb is also greater than the lower limit set pressure P _L , and the upper limit set pressure P _H is the first intermediate set pressure Psa. The second intermediate set pressure Psb may be larger than any of the second intermediate set pressures Psb.

It is a systematic diagram of the compressor concerning the form of the present invention. It is a figure which shows the relationship between the discharge pressure P and the driving | running state of the compressor which concerns on the form of this invention. It is a control system figure which shows the conventional Example.

Explanation of symbols

20 ... Compressor body, 20a ... Suction port, 20b ... Discharge port, 21 ... Suction adjustment valve,
22 ... motor, 23 ... oil recovery device, 24 ... oil separator, 25 ... air release valve,
26 ... Check valve, 27 ... Pressure detecting means, 28 ... Suction passage, 29 ... Discharge passage,
DESCRIPTION OF SYMBOLS 30 ... Controller, 31 ... Oil sump, 32 ... Oil flow path, 33 ... Oil filter 34 ... Oil cooler, 35 ... Air discharge flow path, 36 ... Bypass flow path, 37 ... Orifice

Claims (12)

A suction adjustment valve is provided, and includes a compressor body that compresses the gas sucked from the suction passage that allows passage of a certain amount of gas even when the suction adjustment valve is fully closed. A discharge passage having one end connected to the outlet, and a discharge valve provided in the discharge passage for releasing a part of the compressed gas branched from the discharge passage and passing through the discharge passage; A pressure detecting means for detecting the discharge pressure P of the gas supplied to the gas supply destination is provided on the gas supply destination side from the branching point to the air discharge flow path, and the opening and closing control of the suction adjustment valve and the air discharge valve is performed. in the compressor comprising a control device for the controller, and its interior the lower limit set pressure P _L, a first intermediate set pressure Psa made larger than the lower limit set pressure P _L, than the lower limit set pressure P _L The second intermediate set pressure Psb that increases and the first intermediate set pressure Psa Than either of the second intermediate set pressure Psb and a large becomes the upper limit set pressure P _H is set in advance, and reaches the lower limit set pressure P _L the discharge pressure P is lowered, open vital suction adjustment valve Hokiben The A operation control is carried out as the intermediate load operation in which the suction adjustment valve is closed and the air discharge valve is closed when the discharge pressure P increases and reaches the first intermediate set pressure Psa. on the other hand, reaches the upper limit set pressure P _H discharge pressure P is increased, and the unload operation for opening the closing vital Hokiben suction regulating valve, a second intermediate set pressure discharge pressure P is lowered A compressor having a function of performing B operation control as the intermediate load operation when reaching Psb.   During the intermediate load operation in the A operation control, the controller switches to the B operation control when the discharge pressure P becomes higher than the first intermediate set pressure Psa, while the intermediate load operation in the B operation control 2. The compressor according to claim 1, further comprising a function of switching to A operation control when the discharge pressure P becomes lower than the second intermediate set pressure Psb.   During the intermediate load operation in the A operation control, the controller switches to the B operation control when the discharge pressure P becomes higher than the first intermediate set pressure Psa by a predetermined pressure ΔPsa. 2. A function of switching to A operation control when the discharge pressure P becomes lower than a pressure value lower than the second intermediate set pressure Psb by a predetermined pressure ΔPsb during the intermediate load operation at. The compressor described.   2. The controller according to claim 1, further comprising a function of stopping the operation of the compressor body when a duration of the unload operation in the B operation control exceeds a predetermined time. 4. The compressor according to any one of items 3 to 3.   5. The controller according to claim 1, wherein the controller has a function of switching to the road operation when the duration of the intermediate load operation in the A operation control exceeds a predetermined time. The compressor according to any one of the items.   The compressor according to any one of claims 1 to 5, wherein the first intermediate set pressure Psa and the second intermediate set pressure Psb have the same value. A suction adjustment valve is provided, and includes a compressor main body that compresses the gas sucked from the suction flow passage that allows passage of a certain amount or less of gas even when the suction adjustment valve is fully closed. A discharge passage having one end connected to the outlet, and a discharge valve provided in the discharge passage for releasing a part of the compressed gas branched from the discharge passage and passing through the discharge passage; In the operation control method for a compressor, in which the pressure detection means for detecting the discharge pressure P of the gas supplied to the gas supply destination is provided on the gas supply destination side from the branching point to the air discharge flow path, the lower limit set pressure P _L a, a first intermediate set pressure Psa made larger than the lower limit set pressure P _L, and the second intermediate set pressure Psb made larger than the lower limit set pressure P _L, the first intermediate set pressure Psa, a second intermediate set pressure any large comprising upper set pressure P _H and a preset than the Psb In accordance with the discharge pressure P, any one of the following operation controls is performed.
・ When the discharge pressure P decreases and reaches the lower limit set pressure P _L , load operation is performed to open the suction adjustment valve and close the discharge valve, and the discharge pressure rises to the first intermediate set pressure Psa. If, it reaches the upper limit set pressure P _H a operation control, the discharge pressure P of the intermediate load operation to close the valve closing vital Hokiben suction adjustment valve rises, closes the suction adjustment valve vital The B operation control is set to the unload operation in which the release valve is opened and the intermediate load operation is performed when the discharge pressure P decreases and reaches the second intermediate set pressure Psb.   During the intermediate load operation in the A operation control, when the discharge pressure P becomes higher than the first intermediate set pressure Psa, the operation is switched to the B operation control. On the other hand, during the intermediate load operation in the B operation control, the discharge pressure P is changed. 8. The operation control method for a compressor according to claim 7, wherein when the pressure becomes lower than the second intermediate set pressure Psb, the operation control is switched to the A operation control.   During the intermediate load operation in the A operation control, when the discharge pressure P becomes a pressure higher than the first intermediate set pressure Psa by a predetermined pressure ΔPsa, the operation is switched to the B operation control, while the intermediate load operation in the B operation control is performed. 8. The operation control method for a compressor according to claim 7, wherein when the discharge pressure P becomes lower than a pressure value lower than the second intermediate set pressure Psb by a predetermined pressure ΔPsb, the operation control is switched to A operation control.   10. The operation of the compressor body is stopped when a duration time during the unload operation in the B operation control exceeds a predetermined time. The operation control method for the compressor according to the item.   The compression according to any one of claims 7 to 10, wherein when the duration time during the intermediate load operation in the A operation control exceeds a predetermined time, the operation is switched to the load operation. Machine operation control method. The compressor operation control method according to any one of claims 7 to 11, wherein the first intermediate set pressure Psa and the second intermediate set pressure Psb have the same value.

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