Compressor control system and compressor control method

Abstract

To provide a compressor control system and a compressor control method, each enabling materialization of energy saving.SOLUTION: A compressor control system is used, which comprises: a compressor 11 compressing gas; a the-number-of-units control board 20; and a pressure gauge PSn measuring a terminal pressure of a piping system connected to the compressor 11. A package compressor 31 includes a measuring part 1, a determination part 2, a setting part 3, a control part 4, and the compressor 11. The the-number-of-units control board 20 includes a measuring part mn and an analogue output part 15. The -number- of-units control board 20 transmits first pressure received by the measuring part mn from the pressure gauge PSn as an analogue signal from the analogue output part 15 to the measuring part 1. In the package compressor 31, the measuring part 1 transmits the received analogue signal to the determination part 2 as pressure. The determination part 2 determines the relationship between the threshold value stored in the setting part 3 in advance and the pressure. The control part 4 performs a pressure control by controlling the compressor 11 based on the determination result of the determination part 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a compressor control system and a compressor control method for delivering compressed air using a compressor. [Background technology]

[0002] In compressor control systems that use compressors to supply compressed air to air tools, air blowers, air guns, etc., it is known that so-called rotation speed control is performed to maintain the compressed air pressure within a certain range within the system. Patent Document 1 (JP 2010-24845 A) describes a method of detecting the pressure of each discharge air line, calculating the fluctuation in the pressure difference from the compressor outlet to each terminal, and operating the compressed air production equipment at a minimum pressure setting or discharge air volume. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-24845 Summary of the Invention [Problem to be solved by the invention]

[0004] One method for detecting the compressed air pressure in a compressor control system is to use a pressure gauge installed inside the compressor. However, this method does not allow for the compressed air pressure at the end of the compressor control system (the load equipment side). To address this issue, it is possible to set the pressure inside the compressor (source pressure) higher in order to prevent the compressed air pressure at the end from falling below the required pressure. This results in increased energy consumption by the compressor control system.

[0005] The technology described in the present disclosure aims to provide a compressor control system and a compressor control method that can achieve energy savings. [Means for solving the problem]

[0006] A brief summary of a representative embodiment of the present invention will be given below.

[0007] A compressor control system according to one embodiment includes a first package compressor that compresses gas, a unit control panel, and a first pressure gauge that measures the end pressure of a piping system connected to the first package compressor. Here, the first package compressor includes a first measurement unit, a first determination unit, a first setting unit, a control unit, and a compressor, and the unit control panel includes a second measurement unit and an analog output unit. The unit control panel transmits a first pressure received from the first pressure gauge by the second measurement unit to the first measurement unit from the analog output unit. In the first package compressor, the first measurement unit transmits the received analog signal as a pressure to the first determination unit, and the first determination unit determines a relationship between the pressure and a threshold value pre-stored in the first setting unit. The control unit controls the compressor based on the determination result of the first determination unit to perform compression control.

[0008] One embodiment of a compressor control method includes: (a) operating a first package compressor having a first measuring unit, a first judgment unit, a first setting unit, a control unit, and a compressor, and sending compressed gas to a piping system; (b) after step (a), receiving the pressure measured by a first pressure gauge connected to the end of the piping system with a second measuring unit in a number control panel, and sending an analog signal as a control pressure from the analog output unit in the number control panel to the first measuring unit; and (c) within the first package compressor, sending the analog signal received by the first measuring unit as a pressure to the first judgment unit, and the first judgment unit determining the relationship between the pressure and a threshold value pre-stored in the first setting unit, and based on the determination result, the control unit controlling the compressor to perform compression control. [Effects of the Invention]

[0009] The effects obtained by the representative inventions disclosed in this application will be briefly explained as follows.

[0010] According to the present disclosure, it is possible to provide a compressor control system and a compressor control method that can achieve energy savings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating a compressor control system according to an embodiment. [Figure 2] 1 is a schematic diagram illustrating a compressor control system according to an embodiment. [Figure 3] 10 is a flow chart showing the operation of the unit count control panel according to the embodiment. [Figure 4] 10 is a flowchart showing an operation of a compressor after a signal is output from the unit count control panel according to the embodiment. [Figure 5] 4 is a graph showing an image of pressure control by the compressor control system. [Figure 6] 10 is a flowchart showing the operation of a unit count control panel according to a first modification of the embodiment. [Figure 7] 10 is a flowchart showing the operation of a unit count control panel according to a second modification of the embodiment. [Figure 8] FIG. 10 is a schematic diagram showing a compressor control system according to a third modification of the embodiment. [Figure 9] FIG. 10 is a schematic diagram showing a compressor control system according to a fourth modified example of the embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a compressor control system according to a fifth modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all drawings for explaining the embodiments, components having the same functions are designated by the same reference numerals, and repeated explanations thereof will be omitted. Furthermore, in the following embodiments, explanations of identical or similar parts will not be repeated unless specifically required. Furthermore, in the drawings for explaining the embodiments, hatching may be used even in plan views or perspective views to make the configuration easier to understand. Furthermore, in the drawings for explaining the embodiments, hatching may be omitted in cross-sectional views to make the configuration easier to understand.

[0013] "Pressure" in this application refers to the pressure of gas inside a tank or pipe after being compressed by a compressor in a compressor control system and before being discharged from a discharge port provided in a load facility. Also, the terms "pressure" and "pressure value" in this application have the same meaning. Furthermore, although the embodiments describe compressing and discharging air, the gas to be compressed may be a gas other than air (e.g., nitrogen gas).

[0014] The details of the embodiment will be described below.

[0015] (Embodiment) Fig. 1 shows a schematic diagram of a compressor control system according to this embodiment. As shown in Fig. 1, the system has a unit control panel 20 and package compressors 30 and 31. The unit control panel 20 is connected to each of the package compressors 30 and 31. The unit control panel 20 may control a plurality of package compressors as shown in Fig. 1, or it may control a single package compressor.

[0016] The package compressor 30 has a constant-speed compressor housed within a housing. The compressor 10 (see FIGS. 8 and 9) includes an air end that compresses air using power, a motor that operates at a constant speed, and a switch that supplies / cuts off power to the motor. The package compressor 31 has a variable-speed compressor housed within a housing. The compressor 11 (see FIG. 2) includes an air end that compresses air using power, a controller (such as an inverter) that controls the rotation speed, and a motor whose rotation speed can be adjusted by the controller. These motors are used to drive the air end. In one embodiment, each of the package compressors 30 and 31 has an air tank built into the housing. However, compressors with air tanks located outside the package may also be used. In FIG. 1, only the package compressors 30 and 31 are connected to the unit control panel 20, but more package compressors may be connected to the unit control panel 20. In this embodiment, of the package compressors connected to the unit count control panel 20, only one package compressor is controlled in rotation speed at the same timing, and the remaining package compressors are controlled at a constant speed even if they are variable speed compressors, but the scope of application of the present invention is not limited to this.

[0017] The air tank is connected to piping 9, which is an air flow path extending to the outside of each of the package compressors 30 and 31. The piping 9 branches out toward multiple terminals (downstream) to form a piping system. Compressed air (compressed gas) is discharged from each of the package compressors 30 and 31 to the piping 9. A plurality of flow meters Q for measuring the flow rate of the compressed air and a plurality of pressure gauges Pm for measuring the pressure of the compressed air are provided along the piping 9. In FIG. 1, the pressure gauges Pm are hatched. A plurality or a single load equipment 25, 26, 27, and 28 are provided near the terminals of the piping system relative to the package compressors 30 and 31. Many of the pressure gauges Pm are located closer to the terminals (downstream) of the load equipment. The load equipment 25, 26, 27, and 28 are each a different type of appliance that uses the compressed air discharged from the package compressors 30 and 31 as power. In this manner, in this embodiment, a plurality of load equipment and pressure gauges are provided at the end of the piping system extending from the package compressor (compressor). The end pressure values ​​measured by each of the plurality of pressure gauges Pm are transmitted to the unit control panel 20 via wire or wirelessly.

[0018] FIG. 2 is a schematic diagram of a compressor control system according to this embodiment. FIG. 2 shows, as an example, the package compressor 31 and air tank 8 of FIG. 1 , as well as the unit control panel 20 and piping 9 external to the package compressor 31. The compressor 11 and air tank 8 are interconnected by piping 7. The pressure of the air in the piping 7 within the package compressor 31 is measured by a pressure gauge PS0 installed in the piping 7. That is, the pressure gauge PS0 is installed in the piping 7 upstream of the air tank 8. In this application, the pressure measured anywhere from the piping within the package compressor to the air tank external to the package compressor is referred to as the source pressure. This source pressure naturally includes the pressure in the air tank within the package compressor and the pressure in the piping to the air tank external to the package compressor. Although not shown in FIG. 2 , if a pressure gauge is installed in the air tank 8, the pressure measured by that pressure gauge is the source pressure. The pressure measured by any other pressure gauge, i.e., a pressure gauge installed in the piping downstream of the air tank, is referred to as the terminal pressure.

[0019] The package compressor 31 includes a measuring unit 1, a determining unit 2, a setting unit 3, a control unit 4, and a compressor 11. The measuring unit 1 is connected to the determining unit 2, and the setting unit 3 is connected to the determining unit 2. The control unit 4 is connected to the compressor 11. The compressor 11 includes a controller CTL, an air end (air compression device) AE, and a motor M that operates the air end AE, and compresses air and sends it out through a pipe 7 to an air tank 8. Within the package compressor 31, a pressure gauge PS0 is provided in the pipe 7. Compressed air is sent out from the air tank 8 through a pipe 9, at the end of which pressure gauges PS1 to PSn are provided. Of the pressure gauges PS1 to PSn, only pressure gauges PS1 and PSn are shown in FIG. 2.

[0020] As described above, the unit count control panel 20 is installed separately from the package compressors 30 and 31, which include compressors. The unit count control panel 20 includes a measurement unit m0, a measurement unit mn, a determination unit 12, a setting unit 13, a calculation unit 14, and an analog output unit 15. The measurement units m0 and mn are each connected to the determination unit 12, and the setting unit 13 is connected to the determination unit 12 and the calculation unit 14. The calculation unit 14 is connected to the analog output unit 15.

[0021] Information measured by the pressure gauge PS0 (source pressure) is sent to the measuring unit m0, and information measured by the pressure gauge PSn (terminal pressure) is sent to the measuring unit mn. These pressure values ​​may be transmitted by wire or wirelessly. The analog output unit 15 transmits an analog signal (pressure value, control pressure) to the measuring unit 1 in the package compressor 31.

[0022] <Explanation of operation> Next, the operation of unit control panel 20 in the compressor control method of this embodiment will be described. The control method performed by unit control panel 20 in this embodiment is referred to as the transparent mode. Figure 3 shows a flow chart of the operation of unit control panel 20 when the transparent mode is used in this embodiment.

[0023] As shown in FIG. 3, first, after starting the process, the setting unit 13 is set to the transmission mode (step S1 in FIG. 3). Next, the pressure gauge PSn is used to measure the terminal pressure Pn (step S2 in FIG. 3). Next, the determination unit 12 associates the terminal pressure Pn with the transmission mode (step S3 in FIG. 3). As a result, the determination unit 12 recognizes that the terminal pressure Pn sent from the measurement unit mn is to be used in the transmission mode. The determination unit 12 determines in which mode the compressor control system is to be operated. Modes other than the transmission mode will be described later in Modifications 2 and 3, but these modes can be changed to other modes during operation of the compressor control system. In addition, the determination unit 12 determines which pressure value is the lowest among the pressure values ​​sent from the measurement units, and sends the pressure value determined to be the lowest to the analog output unit 15 via the calculation unit 14. Note that the determination unit 12 may select a pressure value based on other criteria rather than determining the smallest pressure value among multiple pressure values.

[0024] Next, the analog output unit 15 outputs an analog signal to the package compressor 31 as the control pressure P (=terminal pressure Pn) (step S4 in FIG. 3). In the permeation mode, no calculation is performed by the calculation unit 14 between steps S3 and S4. In other words, if the permeation mode is the only mode used in the compressor control system, the calculation unit 14 may not be necessary. The control pressure as used herein refers to the pressure value to be controlled, and is the pressure value used for pressure control in the compressor control system.

[0025] This analog signal may be transmitted wirelessly or via a wire. Even when the unit control panel 20 and the package compressor 31 are connected via a wire and multiple pieces of terminal pressure information are transmitted from multiple pressure gauges PS0 to the unit control panel 20, only one signal is output from the unit control panel 20, so the package compressor 31 only needs to have one signal receiving port.

[0026] Upon receiving the analog signal, the package compressor 31 recognizes that its own source pressure is Pn and controls its rotation speed as follows: In reality, the source pressure of the package compressor 31 is P0 measured by the pressure gauge PS0, but in this embodiment of FIG. 3, this value is not used for control.

[0027] Next, the operation of the package compressor 31 that has received the analog signal will be described with reference to FIG. 4. FIG. 4 is a flow chart showing the operation of the package compressor 31 after the analog signal is output from the unit count control panel 20 in step S4 of FIG. 3 according to this embodiment. The analog signal output from the unit count control panel 20 is received and measured by the measurement unit 1 in the package compressor 31 (step S5 of FIG. 4). Next, the determination unit 2 determines the relationship (magnitude relationship) between a value (threshold) pre-stored in the setting unit 3 and the measurement value measured in step S5 (step S6 of FIG. 4). The value (threshold) pre-stored in the setting unit 3 is, for example, the lower and upper limits of a pressure threshold band that serves as a reference for rotation speed control. The relationship here refers to a state in which the measurement value (pressure value) is within the range from the lower limit to the upper limit of the pressure threshold band, the measurement value exceeds the upper limit, or the measurement value is below the lower limit. Specifically, the determination unit 2 determines the difference between the measurement value and each of the lower and upper limits of the pressure threshold band.

[0028] Next, the control unit 4 transmits a rotation speed control signal to the compressor 11 based on the determination made in step S6, thereby controlling the rotation speed of the compressor 11 (step S7 in FIG. 4). That is, the controller CTL of the compressor 11 controls the speed of the motor M in accordance with the control signal, thereby controlling the operation of the air end AE. If the measurement value is within the range from the lower limit to the upper limit of the pressure threshold band, the frequency of the rotation speed control signal sent from the control unit 4 to the compressor 11 is not changed. If the measurement value exceeds the upper limit of the pressure threshold band, the control unit 4 reduces the frequency of the rotation speed control signal sent to the compressor 11, thereby slowing down the rotation of the motor M. If the measurement value is below the lower limit of the pressure threshold band, the control unit 4 increases the frequency of the rotation speed control signal sent to the compressor 11, thereby speeding up the rotation of the motor M. In this way, the pressure of the air discharged from the piping 7 to the outside of the package compressor 31 is controlled to remain within the pressure threshold band as much as possible.

[0029] <Effects of this embodiment> FIG. 5 is a graph showing the relationship between compressed air pressure and time in the compressor control systems of the comparative example and the present embodiment. The horizontal axis of the graph in FIG. 5 represents time, and the vertical axis represents pressure. In FIG. 5, the source pressure measured by a pressure gauge installed in the package compressor before the introduction of the comparative compressor control system is shown as a relatively thin solid line in Graph 1A, and the terminal pressure measured by a pressure gauge installed at the end of the compressor before the introduction of the comparative compressor control system is shown as a relatively thin dashed-dotted line in Graph 1B. Also in FIG. 5, the source pressure measured by a pressure gauge PS0 installed in the compressor of the present embodiment is shown as a relatively thick solid line in Graph 2A, and the terminal pressure measured by a pressure gauge PSn installed at the end of the compressor of the present embodiment is shown as a relatively thick dashed-dotted line in Graph 2B. Both the left and right vertical axes in FIG. 5 represent pressure, with the values ​​at the bottom of each vertical axis being the same and the values ​​at the top of each vertical axis being the same.

[0030] The vertical axis on the right side of Figure 5 marks the pressure values ​​LLL1, LL1, L1, H1, HH1, and HHH1 in ascending order. These are values ​​that serve as a guide for pressure control before the introduction of the compressor control system of the comparative example. The vertical axis on the left side of Figure 5 marks the pressure values ​​LLL2, LL2, L2, H2, HH2, and HHH2 in ascending order. These are values ​​that serve as a guide for pressure control in the compressor control system of this embodiment. In Figure 5, the required pressure for the terminal load equipment is shown by a two-dot chain line near pressures LLL1 and LLL2.

[0031] In a comparative example in which the rotation speed is controlled by feedback of the source pressure, pressure control is performed so that the source pressure falls within a pressure threshold band between pressure L1 and pressure H1. In contrast, in this embodiment in which the rotation speed is controlled by feedback of the end pressure, pressure control is performed so that the end pressure falls within a pressure threshold band between pressure L2 and pressure H2. Here, when the end pressure falls below pressure L2, the rotation of motor M is increased to increase the pressure. When the end pressure falls below pressure LL2, the rotation of motor M is increased more rapidly with high output to increase the pressure. When the end pressure falls below pressure LLL2, the rotation of motor M is increased more rapidly than when the end pressure falls below pressure LL2. Furthermore, when the end pressure exceeds pressure H2, the rotation of motor M is slowed to decrease the pressure. When the end pressure exceeds pressure HH2, the rotation of motor M is slowed more rapidly to decrease the pressure. When the end pressure exceeds pressure HHH2, the rotation of motor M is slowed more rapidly to decrease the pressure. When the end pressure exceeds pressure HHH2, the rotation of motor M is slowed more rapidly to decrease the pressure.

[0032] In this embodiment, instead of measuring only the source pressure, the terminal pressure is constantly measured and the terminal pressure is fed back to control the operation of the compressor. Therefore, compared to when the rotation speed is controlled by measuring the source pressure without measuring the terminal pressure, the compressor control system can be operated at a pressure closer to the required pressure for the terminal load equipment. In other words, as shown in Figure 5, compared to graphs 1A and 1B of the comparative example, graphs 2A and 2B of this embodiment move at lower values ​​closer to the required pressure for the terminal load equipment, thereby achieving energy savings.

[0033] Furthermore, in this embodiment, since the terminal pressure is measured, fine pressure control is possible, and therefore the width of the pressure threshold band between pressure L2 and pressure H2 (between the upper and lower limits of the pressure threshold band) can be narrower than the width of the pressure threshold band between pressure L1 and pressure H1, enabling further energy savings.

[0034] The measuring unit 1 shown in FIG. 2 recognizes the received analog signal as the discharge pressure of the package compressor 31 (the source pressure measured by the pressure gauge PS0) and operates accordingly. Therefore, any type of compressor that measures the source pressure and controls pressure can be used in the compressor control system of this embodiment. In other words, one of the main features of this embodiment is that a unit control panel 20 is provided, a single analog signal is sent from the unit control panel 20 to the package compressor 31, and the analog signal is recognized as the discharge pressure of the package compressor 31 and operates accordingly. This applies whether a single pressure value is sent to the unit control panel 20 or multiple pressure values ​​are sent. Therefore, even when pressure control is performed by collecting multiple pressure values ​​from multiple terminal pressure gauges, there is no need to prepare a unit control panel capable of measuring such multiple pressures. In other words, there is no need to prepare a unit control panel with multiple measuring units and signal receiving ports corresponding to multiple pressure gauges. This allows for energy savings at low cost.

[0035] Furthermore, even if the unit control panel 20 receives multiple pressure values ​​from each pressure gauge, the package compressor 31 receives only one analog signal from the unit control panel 20, and therefore, unlike the comparative example, the unit control panel 20 does not need to perform complex control such as PID control.

[0036] Furthermore, the operation of the package compressor 31 may be controlled not only by the terminal pressure but also based on the source pressure within the package compressor 31. To enable such control switching, in this embodiment, not only the terminal pressure measured by the pressure gauge PSn but also the source pressure measured by the pressure gauge PS0 is transmitted to the unit control panel 20. This allows the rotation speed to be controlled even when the package compressor 31 is operated independently.

[0037] As described above, the compressor control system of this embodiment measures the terminal pressure and controls the pressure, thereby realizing energy savings for the entire system. Also, the compressor control system of this embodiment uses a multiple-unit control panel to send the results of measurements at multiple terminal pressures to the package compressor as a single analog signal, and the package compressor controls the pressure based on this analog signal, preventing the control of the entire system from becoming complicated.

[0038] <Variation 1> The operation mode of the unit control panel 20 may be a pressure difference correction mode, which performs more stable rotation speed control by taking into account the average value of the pressure difference as described below, instead of the transmission mode described above.

[0039] The operation of unit control panel 20 in the compressor control method of Modification 1 will be described below. The control method performed by unit control panel 20 in this modification is referred to as the pressure difference correction mode. Fig. 6 shows a flow chart of the operation of unit control panel 20 when the pressure difference correction mode is used in this embodiment.

[0040] As shown in FIG. 6, first, after starting the process, the setting unit 13 is set to the pressure difference correction mode (step S11 in FIG. 6). Next, the pressure gauge PS0 is used to measure the base pressure P0 (step S12 in FIG. 6). Next, the pressure gauge PSn is used to measure the terminal pressure Pn (step S13 in FIG. 6). The order of steps S12 and S13 may be reversed, or they may be performed simultaneously. Next, the determination unit 12 associates the base pressure P0 and the terminal pressure Pn with the pressure difference correction mode (step S14 in FIG. 6). As a result, the determination unit 12 recognizes that the base pressure P0 and the terminal pressure Pn sent from the measurement units m0 and mn will be used in the pressure difference correction mode. Next, the calculation unit 14 calculates the average value ΔP(TYP) of the pressure difference over a certain interval, ie, P0-Pn (step S15 in FIG. 6). In other words, the pressure difference ΔP in the section between the position of the pipe to which pressure gauge PS0 is connected and the position of the pipe to which pressure gauge PSn is connected is calculated multiple times within a specified period of time, and these are averaged to calculate ΔP(TYP).

[0041] Next, the analog output unit 15 outputs the control pressure P as an analog signal to the package compressor 31 (step S16 in FIG. 6). The control pressure P is calculated by the calculation unit 14 as P=P0-ΔP(TYP) or P=Pn+ΔP(TYP). Either of these methods may be used to calculate the control pressure P.

[0042] Thereafter, the package compressor 31 performs steps S5 to S7 described with reference to FIG.

[0043] In this modification, the package compressor does not operate instantaneously by measuring the instantaneous end pressure Pn, but performs correction control based on the average value ΔP(TYP) of the pressure difference over a certain interval. In other words, the package compressor does not increase or decrease the pressure by a large fluctuation range over a short period of time, but the pressure controlled by the package compressor is controlled to fluctuate by a small fluctuation range over a predetermined time, allowing for relatively stable control.

[0044] <Variation 2> The operation mode of the unit control panel 20 may be a pressure time difference correction mode, which performs predictive control taking into account the transmission time difference between P0 and Pn as described below, thereby achieving more accurate rotation speed control, in addition to the pressure difference correction mode.

[0045] The operation of the number of units control panel 20 in the compressor control method of Modification 2 will be described below. The control method performed by the number of units control panel 20 in this modification is referred to as the pressure time difference correction mode. Fig. 7 shows a flow chart of the operation of the number of units control panel 20 when the pressure time difference correction mode is used in this embodiment.

[0046] As shown in FIG. 7, first, after starting the process, the setting unit 13 is set to the pressure-time difference correction mode (step S21 in FIG. 7). Next, the pressure gauge PS0 is used to measure the base pressure P0 (step S22 in FIG. 7). Next, the pressure gauge PSn is used to measure the terminal pressure Pn (step S23 in FIG. 7). The order of steps S22 and S23 may be reversed, or they may be performed simultaneously. Next, the determination unit 12 associates the base pressure P0 and the terminal pressure Pn with the pressure-time difference correction mode (step S24 in FIG. 7). As a result, the determination unit 12 recognizes that the base pressure P0 and the terminal pressure Pn sent from the measurement units m0 and mn will be used in the pressure-time difference correction mode.

[0047] Next, the calculation unit 14 calculates the transmission time difference ΔT(TYP) between P0 and Pn (step S25 in FIG. 7). Referring to the graphs shown in FIG. 5, the source pressure graph 2A and the end pressure graph 2B appear to fluctuate in the same manner at exactly the same timing, but in reality, they fluctuate with a slight time difference. For example, when the source pressure reaches its peak, the end pressure also reaches its peak a short time later. In other words, a time difference (transmission time difference ΔT) occurs in the transmission of pressure between the pressure gauge PS0 and the pressure gauge PSn. In step S25, the calculation unit 14 calculates the transmission time difference ΔT between the time when P0 reaches its peak and the time when Pn reaches its peak multiple times, and calculates the transmission time difference ΔT(TYP), which is the average value of these ΔTs. Note that the peak here refers to both a crest and a trough.

[0048] Next, the calculation unit 14 calculates the average value of the pressure difference ΔP'(TYP)=P0-Pn in a certain section, taking into account the transmission time difference ΔT (step S26 in FIG. 7). That is, the calculation unit 14 calculates a plurality of pressure differences ΔP in the section between the position of the pipe to which the pressure gauge PSn is connected and the position of the pipe to which the terminal pressure Pn is connected within a predetermined time, and calculates the average of these ΔP(TYP). ΔP', which is calculated taking into account the transmission time difference ΔT, is calculated from the time when the source pressure P0 is measured. This is a prediction of the end pressure Pn after ΔT from the measurement of the end pressure Pn, or a prediction of the original pressure P0 after ΔT from the measurement of the end pressure Pn.

[0049] Next, the analog output unit 15 outputs the control pressure P as an analog signal to the package compressor 31 (step S27 in FIG. 7). The calculation unit 14 calculates the control pressure P by P=P0-ΔP'(TYP) or P=Pn+ΔP'(TYP). Either of these methods may be used to calculate the control pressure P.

[0050] Thereafter, the package compressor 31 performs steps S5 to S7 described with reference to FIG.

[0051] In this modification, as in the first modification, the control pressure P is calculated based on the average value ΔP(TYP) of the pressure difference over a certain period, and therefore has the characteristics of a pressure time difference correction mode, enabling relatively stable control. In addition, predictive control is performed taking into account the transmission time difference ΔT, so the range of fluctuation in pressure during rotation speed control is small, enabling more stable control. Here, calculating ΔP' by predicting the terminal pressure Pn after ΔT from the source pressure P0 in step S26 enables more accurate control in response to changes in the amount of compressed air supplied. Furthermore, calculating ΔP' by predicting the source pressure P0 after ΔT from the terminal pressure Pn in step S26 enables more accurate control in response to changes in the amount of compressed air used.

[0052] <Variation 3> A case where the terminal pressures measured by a plurality of pressure gauges are grouped will be described. Fig. 8 is a schematic diagram showing a compressor control system according to this modification. The compressor control system shown in Fig. 8 differs from the compressor control system shown in Fig. 2 in the following points.

[0053] In this modification, the pipe 9 branches into multiple branches downstream of the air tank 8, and pressure gauges PS3 to PSn are provided at the ends of each of the multiple branches. Furthermore, pressure gauge PS1 is provided in the pipe 9 closer to the air tank 8 than the downstream side (end) of the pipe 9. Furthermore, pressure gauge PS2 is provided in the pipe 9 downstream of pressure gauge PS1 and upstream of the point where the pipe 9 branches into multiple branches. In this modification, for example, pressure gauges PS4 and PS5 belong to group A, and pressure gauges PS2 and PS3 belong to group B. That is, the pressure gauges are arranged from the first pressure gauge PS1 to the nth pressure gauge PSn, where n is a positive natural number. The load equipment near pressure gauges PS4 and PS5 belong to group A, and the load equipment near pressure gauges PS2 and PS3 belong to group B. However, it is not necessary for some of these pressure gauges to have no load equipment near them. It should be noted that although the pressure gauges PS1 and PS2 shown in FIG. 8 are located on the upstream side compared to the pressure gauges PS3 to PSn, the pressures measured by these two pressure gauges PS1 and PS2 are end pressures.

[0054] The unit count control panel 20 includes a measuring unit m0 that receives pressure values ​​from the pressure gauge PS0 and multiple measuring units m1 to mn that receive pressure values ​​from the pressure gauges PS1 to PSn. In other words, the unit count control panel 20 includes a total of n+1 measuring units, consisting of the measuring unit m0 and n measuring units m1 to mn. The unit count control panel 20 also includes a grouping determining unit 12a instead of the determining unit 12, and a load / unload control output unit 16 in addition to the analog output unit 15. While FIG. 8 illustrates the compressor 11 and the load / unload operation unit 6 within the package compressor 31, in reality, the package compressor 31 (variable speed) equipped with the compressor 11 and the package compressor 30 (fixed speed) equipped with the load / unload operation unit 6 are provided separately (see FIG. 9). These are the differences between the configuration of the compressor control system shown in FIG. 8 and the configuration of the compressor control system shown in FIG. 2.

[0055] In this embodiment, the load / unload operation unit 6 is built into the package compressor 30 shown in Fig. 1, but the present invention is not limited to this. A variable speed machine (package compressor 31) may have a load / unload operation unit, or a constant speed machine (package compressor 30) may be a package compressor that does not have a load / unload operation unit.

[0056] Furthermore, the load / unload control output unit 16 of the unit count control panel 20 may be equipped with a control that measures the elapsed time since the start of unload operation and stops the compressor 10 or 11 itself if the elapsed time is equal to or greater than a predetermined time. During unload operation, compressed air is not generated, but the motor M itself is driven and consumes power. Therefore, if the unload operation time is equal to or greater than a predetermined time, power consumption can be reduced by cutting off power to the motor M to stop the compressor 10 or 11 itself. Of course, this determination may be made by the control unit 4 in the package compressor 30 or 31, rather than by the unit count control panel 20.

[0057] In group A, if the pressures on pressure gauges PS4 and PS5 fall below L2, LL2, or LLL2, pressure control is performed under an OR condition, and if they exceed H2, HH2, or HHH2, control is also performed under an OR condition. That is, for example, if one of the pressures on pressure gauges PS4 and PS5 in group A falls below L2, the control unit 4 increases the rotation speed of motor M to boost the pressure. Also, in group B, if the pressures on pressure gauges PS2 and PS3 fall below L2, LL2, or LLL2, pressure control is performed under an OR condition, and if they exceed H2, HH2, or HHH2, control is also performed under an OR condition. That is, for example, if one of the pressures on pressure gauges PS2 and PS3 in group B falls below L2, the control unit 4 increases the rotation speed of motor M to boost the pressure. When the load equipment of Group A and Group B is used at the same time, for example, when the pressure measured by either the pressure gauge of Group A or the pressure gauge of Group B exceeds a threshold value such as H2 or falls below a threshold value such as L2, the compressor 11 will decrease or increase the pressure in response to an instruction from the control unit 4.

[0058] When group A and group B operate simultaneously, differences in pressure may occur between the groups because the pressure of group B is measured at a position closer to the package compressor 31 (upstream side) than that of group A. In this case, pressure control is performed so that the pressure of group A and group B falls within different pressure threshold bands. In other words, the target pressures H2 and L2 of group A and the target pressures H2 and L2 of group B may be different values.

[0059] Furthermore, the load equipment of groups A and B is not operated at the same time, and the operation timing (time period) may differ. For example, if group A is not operated, there is no need to ensure that the pressures at the pressure gauges PS4 and PS5 of group A maintain the pressure required for the terminal load equipment. Therefore, in this case, pressure control is performed to maintain the target pressure (pressure threshold band) of group B. In other words, the calculation unit 14 outputs information on the pressure of group B to the package compressor 31 as an analog signal.

[0060] Furthermore, the types of load equipment in Group A and Group B may differ. In this case, the target pressure (pressure threshold band) or the required pressure for the terminal load equipment may differ between Group A and Group B. For example, if the pressure value in Group B is lower than the pressure value in Group A, the pressure value in Group A may be below the lower limit (L2) of the target pressure threshold band, while the pressure value in Group B may be above the lower limit (L2) of the target pressure threshold band. In such a case, pressure control is performed to increase the pressure in Group A so that it falls within the pressure threshold band. In other words, the calculation unit 14 outputs information about the pressure in Group A, which is outside the pressure threshold band, to the package compressor 31 as an analog signal.

[0061] In this modification, the setting unit 13 stores pressure control thresholds (H2, L2, etc.) for each group, and the setting unit 13 associates each group with a target pressure (pressure threshold band) and a required pressure for terminal load equipment. The grouping determination unit 12a determines which group a pressure value sent from the measurement units m1 to mn belongs to. The grouping determination unit 12a also determines whether the group to which the pressure value belongs is a group that currently requires pressure control, that is, whether the group is using load equipment. If the received pressure value is a pressure value for a group that requires pressure control, the grouping determination unit 12a sends information about the pressure value to the calculation unit 14. If the received pressure value is a pressure value for a group that does not require pressure control, the grouping determination unit 12a does not send information about the pressure value to the calculation unit 14. The grouping determination unit 12a also determines which pressure value is the lowest among the pressure values ​​sent from the measurement units m1 to mn, and sends the pressure value determined to be the lowest to the calculation unit 14. That is, based on the storage of the setting unit 13, the grouping determination unit 12a transmits to the calculation unit 14 the pressure values ​​of the groups for which the need for pressure value control is greater.

[0062] In the transmission mode, the calculation unit 14 does not perform any calculations, and transmits the pressure value received from the grouping determination unit 12a as the control pressure to the package compressor 31 via the analog output unit 15. In the pressure difference correction mode or the time difference correction mode, the calculation unit 14 performs the calculations described in the first and second modifications, and transmits the control pressure P calculated as a result to the package compressor 31 via the analog output unit 15.

[0063] Furthermore, when controlling the operation of the constant speed machine, the calculation unit 14 sends a control signal to the load / unload operation unit 6 via the load / unload control output unit 16. The constant speed machine controls the amount of compressed air produced by turning on / off a switch that supplies power to the motor in response to the received control signal, stopping / rotating the motor, and thereby controlling the pressure. Alternatively, the constant speed machine controls the pressure by opening / closing the suction valve of the air end in response to the received control signal, thereby controlling the amount of compressed air produced.

[0064] In this embodiment, the load / unload operation refers to the operation of switching the opening / closing of the suction valve of the air end. During load operation, the suction valve is closed to generate compressed air, and during unload operation, the suction valve is opened to allow the motor to rotate but not generate compressed air.

[0065] The details of the loading / unloading operation are not limited to this, and for example, the operation may be to open / close the discharge valve instead of the suction valve.

[0066] Furthermore, the present invention is not limited to adopting only one of the switch and the load / unload operation, and naturally includes a configuration in which pressure is controlled by controlling both of them together.

[0067] <Variation 4> As shown in FIG. 9, a single unit control panel 20 may be connected to a plurality of package compressors 31a, 30a, and 30b. The package compressor 31a is a variable speed compressor equipped with a compressor 11, similar to the package compressor 31 shown in FIG. 2. The package compressors 30a and 30b are fixed speed compressors equipped with a compressor 10 and a load / unload operation unit 6. The compressor 10 is equipped with a motor M and an air end AE. Unlike the compressor 11, the compressor 10 is equipped with a switch OC instead of a controller CTL. The unit control panel 20 has a structure similar to that shown in FIG. 2. The package compressors 31a, 30a, and 30b are each connected to the same piping system, similar to that shown in FIG. 1. The piping system may have the structure shown in FIG. 2, or may be grouped as described in Modification 3.

[0068] When the compressor control system is in operation, an analog signal is sent from an analog output unit provided in the unit control panel 20 to the measurement unit 1 of each of the package compressors 31a, 30a, and 30b. As a result, the package compressor 31a, which is a variable speed compressor, operates in the same manner as the package compressor 31 described with reference to FIG. 2 and controls the rotation speed. In response to this, the package compressors 30a and 30b receive the analog signal via the measurement unit 1, and the determination unit 2 determines the relationship between a value (threshold) pre-stored in the setting unit 3 and the measurement value measured in step S5. Based on this determination, the control unit 4 sends a control signal to the compressor 10 and the load / unload operation unit 6 to perform the load / unload operation. In other words, the control signal switches between the load operation and the unload operation of the package compressors 30a and 30b, thereby controlling the pressure.

[0069] Even if any one of the package compressors 31a, 30a, and 30b has a different output from the other compressors, the same analog signal is transmitted to each of the package compressors 31a, 30a, and 30b from the unit control panel 20. For example, each of the package compressors 30a, 30b that has received the analog signal transmits a different control signal to its own compressor 10 and loading / unloading operation unit 6 in the control unit 4 according to the output, thereby controlling the pressure.

[0070] In this modified example, there is no need to prepare multiple unit control panels depending on the type of compressor, and there is no need to send different analog signals from the unit control panel depending on the type of compressor, so the configuration of the unit control panel can be simplified.

[0071] <Variation 5> As shown in FIG. 10 , the unit count control panel 20 may be built into the package compressor 31. In this modification, the package compressor 31 is a variable speed machine, and the unit count control panel 20 built into the package compressor 31 outputs an analog signal not only to the measurement unit 1 inside the package compressor 31 but also to the measurement units 1 of the package compressors 30 c and 30 d, which are fixed speed machines installed outside the main package compressor 31. In this case, the measurement unit m0 measures the pressure (source pressure) of the pressure gauge inside the package compressor 31, and the measurement unit mn measures the pressure (terminal pressure) of the terminal pressure gauge outside the package compressor 31. As a result, information on one or more terminal pressures is measured by the unit count control panel 20 inside the package compressor 31, and an analog signal is sent from the analog output unit 15, thereby enabling pressure control by the package compressors 31, 30 c, and 30 d.

[0072] In this modification, by incorporating the function of a unit control panel into the compressor, an inexpensive compressor control system can be realized.

[0073] Even if a sub-compressor is not connected to the main package compressor 31, the same effects as those of the compressor control system described with reference to FIGS. 1 to 5 can be obtained.

[0074] The present invention has been specifically described above based on the embodiments, but it goes without saying that the present disclosure is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the present invention. For example, the compressor to which the analog signal is sent from the unit control panel can be any type of compressor. In other words, the compressor can be, for example, a reciprocating compressor, a screw compressor, a scroll compressor, or a turbo compressor. [Explanation of symbols]

[0075] 1, m0, m1, mn measurement section 2, 12 Judgment section 3, 13 Setting section 4. Control Unit 6 Load / unload operation section 7, 9 Piping 8 Air Tank 10, 11 Compressor 12a Grouping decision unit 14 Arithmetic section 15 Analog output section 16 Unload control output section 20 Unit Control Panel 30, 30a, 30b, 30c, 30d, 31 Package compressor AE Airend CTL Controller Medium motor OC switch Pm, PS0, PS1, PS2, PS3, PS4, PS5, PSn pressure gauges Q flowmeter

Claims

1. a first package compressor for compressing gas; A number control panel and a first pressure gauge that measures an end pressure of a piping system connected to the first package compressor; Equipped with the first package compressor has a first measuring unit, a first determining unit, a first setting unit, a control unit, and a compressor; the unit count control panel has a second measurement unit and an analog output unit, the number control panel transmits the first pressure received from the first pressure gauge by the second measurement unit as an analog signal from the analog output unit to the first measurement unit; a first measuring unit that transmits the received analog signal as a pressure to a first determining unit, the first determining unit determining a relationship between the pressure and a threshold value that is pre-stored in the first setting unit, and the control unit that performs compression control by controlling the compressor based on a determination result of the first determining unit.

2. 2. The compressor control system of claim 1, a second pressure gauge provided inside the first package compressor; a calculation unit and a third measurement unit provided in the unit count control panel; and the number control panel receives the first pressure from the first pressure gauge at the second measurement unit, and receives the second pressure from the second pressure gauge at the third measurement unit; The calculation unit Calculating an average value of pressure differences in a section between the second pressure gauge and the first pressure gauge; calculating a control pressure using the difference between the second pressure and the average value or the sum of the first pressure and the average value; The analog output unit transmits the first pressure or the control pressure as the analog signal.

3. 3. The compressor control system according to claim 2, When the first pressure is Pn and the second pressure is P0, The calculation unit The average value ΔP(TYP) of the pressure difference in the section between the second pressure gauge and the first pressure gauge is calculated using the formula ΔP(TYP)=P0-Pn; The compressor control system calculates the control pressure P using an equation of P = P0 - ΔP(TYP) or an equation of P = Pn + ΔP(TYP), and transmits the control pressure P as the analog signal from the analog output unit to the first measurement unit.

4. 2. The compressor control system of claim 1, a second pressure gauge provided inside the first package compressor; a calculation unit and a third measurement unit provided in the unit count control panel; and the number control panel receives the first pressure from the first pressure gauge at the second measurement unit, and receives the second pressure from the second pressure gauge at the third measurement unit; The calculation unit calculating a pressure transmission time difference between the second pressure gauge and the first pressure gauge; calculating an average value of pressure differences in a section between the second pressure gauge and the first pressure gauge from a difference between the second pressure and the first pressure using the second pressure and the first pressure after the transmission time difference from the time of measurement of the second pressure, or the first pressure and the second pressure after the transmission time difference from the time of measurement of the first pressure; a control pressure calculated from the difference between the second pressure and the average value, or the sum of the first pressure and the average value, and transmitting the control pressure as the analog signal from the analog output unit to the first measurement unit instead of the first pressure.

5. 5. The compressor control system according to claim 4, When the first pressure is Pn and the second pressure is P0, The calculation unit Calculating the pressure transmission time difference ΔT between the second pressure gauge and the first pressure gauge; calculating the average value ΔP'(TYP) of the pressure difference in the section between the second pressure gauge and the first pressure gauge using the formula ΔP'(TYP)=P0-Pn, which uses the second pressure P0 and the first pressure Pn after the transmission time difference ΔT from the time of measurement of the second pressure P0, or the first pressure Pn and the second pressure P0 after the transmission time difference ΔT from the time of measurement of the first pressure Pn; The compressor control system calculates the control pressure P using an equation of P = P0 - ΔP' (TYP) or an equation of P = Pn + ΔP' (TYP), and transmits the control pressure P as the analog signal from the analog output unit to the first measurement unit.

6. 2. The compressor control system of claim 1, a plurality of the first pressure gauges are provided, the number control panel has a second determination unit and a plurality of second measurement units that receive the plurality of pressures transmitted from the plurality of first pressure gauges, the second determination unit determines the smallest pressure among the plurality of pressures transmitted from the plurality of second measurement units; The analog output unit transmits the pressure determined to be the smallest by the second determination unit as the analog signal to the first measurement unit.

7. 2. The compressor control system of claim 1, a plurality of the first pressure gauges are provided, the number control panel has a second determination unit, a second setting unit, and a plurality of second measurement units that receive a plurality of pressures transmitted from the plurality of first pressure gauges, the plurality of first pressure gauges are divided into a plurality of groups; the second setting unit stores in advance which group each of the plurality of pressures transmitted from the plurality of first pressure gauges belongs to; the second determination unit determines a pressure of a group that is more likely to require pressure control based on the storage of the second setting unit; The analog output unit transmits, as the analog signal to the first measurement unit, a pressure that the second determination unit determines to be in a group of pressures that are more in need of control.

8. 2. The compressor control system of claim 1, The compressor control system, wherein the unit control panel is connected to one or more second package compressors in addition to the first package compressor.

9. (a) operating a first package compressor having a first measuring unit, a first determining unit, a first setting unit, a control unit, and a compressor, the first package compressor delivering compressed gas to a piping system; (b) after the step (a), receiving a first pressure measured by a first pressure gauge connected to an end of the piping system with a second measurement unit in a unit control panel, and transmitting the first pressure measured by a first pressure gauge connected to an end of the piping system with an analog output unit in the unit control panel as an analog signal to the first measurement unit; (c) A method for controlling a compressor, in the first package compressor, the analog signal received by the first measuring unit is transmitted as a pressure to the first determining unit, the first determining unit determines a relationship between the pressure and a threshold value pre-stored in the first setting unit, and the control unit performs compression control by controlling the compressor based on the determination result of the first determining unit.

10. 10. The compressor control method according to claim 9, a second pressure gauge provided inside the first package compressor; a calculation unit and a third measurement unit provided in the unit count control panel; and The step (b) includes: (b1) after the step (a), receiving the first pressure measured by the first pressure gauge with the second measuring unit, and receiving the second pressure measured by the second pressure gauge with the third measuring unit; (b2) the calculation unit Calculating an average value of pressure differences in a section between the second pressure gauge and the first pressure gauge; calculating a control pressure using the difference between the second pressure and the average value or the sum of the first pressure and the average value; a step in which the analog output unit transmits the first pressure or the control pressure as the analog signal to the first measurement unit; A compressor control method comprising:

11. 11. The compressor control method according to claim 10, When the first pressure is Pn and the second pressure is P0, In the step (b2), the calculation unit: The average value ΔP(TYP) of the pressure difference in the section between the second pressure gauge and the first pressure gauge is calculated using the formula ΔP(TYP)=P0-Pn; a control method for a compressor, wherein the control pressure P is calculated using an equation of P=P0-ΔP(TYP) or an equation of P=Pn+ΔP(TYP), and transmitted as the analog signal from the analog output unit to the first measurement unit.

12. 10. The compressor control method according to claim 9, a second pressure gauge provided inside the first package compressor; a calculation unit and a third measurement unit provided in the unit count control panel; and The step (b) includes: (b3) after the step (a), receiving the first pressure measured by the first pressure gauge with the second measuring unit, and receiving the second pressure measured by the second pressure gauge with the third measuring unit; (b4) the calculation unit calculating a pressure transmission time difference between the second pressure gauge and the first pressure gauge; calculating an average value of pressure differences in a section between the second pressure gauge and the first pressure gauge from a difference between the second pressure and the first pressure using the second pressure and the first pressure after the transmission time difference from the time of measurement of the second pressure, or the first pressure and the second pressure after the transmission time difference from the time of measurement of the first pressure; calculating a control pressure using the difference between the second pressure and the average value or the sum of the first pressure and the average value; a step in which the analog output unit transmits the control pressure, instead of the first pressure, to the first measurement unit as the analog signal; A compressor control method comprising:

13. 13. The compressor control method according to claim 12, When the first pressure is Pn and the second pressure is P0, In the step (b4), the calculation unit: Calculating the pressure transmission time difference ΔT between the second pressure gauge and the first pressure gauge; calculating the average value ΔP'(TYP) of the pressure difference in the section between the second pressure gauge and the first pressure gauge using the formula ΔP'(TYP)=P0-Pn, which uses the second pressure P0 and the first pressure Pn after the transmission time difference ΔT from the time of measurement of the second pressure P0, or the first pressure Pn and the second pressure P0 after the transmission time difference ΔT from the time of measurement of the first pressure Pn; A method for controlling a compressor, wherein the control pressure P is calculated using an equation of P=P0-ΔP'(TYP) or an equation of P=Pn+ΔP'(TYP), and transmitted as the analog signal from the analog output unit to the first measurement unit.

14. 10. The compressor control method according to claim 9, a plurality of the first pressure gauges are provided, the number control panel has a second determination unit and a plurality of the second measurement units, The step (b) includes: (b5) receiving, by the second measuring units, each of the plurality of pressures measured by the plurality of first pressure gauges; (b6) a step in which the second determination unit determines the smallest pressure among the plurality of pressures transmitted from the plurality of second measurement units; (b7) a step in which the analog output unit transmits the pressure determined to be the smallest by the second determination unit in the step (b6) to the first measurement unit as the analog signal; A compressor control method comprising:

15. 10. The compressor control method according to claim 9, a plurality of the first pressure gauges are provided, the number control panel has a second determination unit, a second setting unit, and a plurality of second measurement units that receive a plurality of pressures transmitted from the plurality of first pressure gauges, the plurality of first pressure gauges are divided into a plurality of groups; (a0) before the step (a), the second setting unit may store information indicating to which group each of the plurality of pressures transmitted from the plurality of first pressure gauges belongs; The step (b) includes: (b8) receiving, by the second measuring units, each of the plurality of pressures measured by the plurality of first pressure gauges; (b9) a step in which the second determination unit determines the pressure of a group that is more in need of pressure control based on the storage in the step (a) of the second setting unit; (b10) a step in which the analog output unit transmits, to the first measurement unit, the pressure determined by the second determination unit in the step (b9) to be a pressure in a group that is more likely to be controlled, as the analog signal; A compressor control method comprising:

16. 10. The compressor control method according to claim 9, The compressor control method, wherein the unit control panel is connected to one or more second package compressors in addition to the first package compressor.

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