JP5444264B2 - Control device for gas compressor - Google Patents

Description

  The present invention relates to a control device for a gas compression device that supplies compressed gas to a tank, for example.

  In general, an air compressor that supplies and stores compressed air to a tank is known (see, for example, Patent Document 1). In the air compressor according to Patent Document 1, the pressure in the tank is detected by a pressure sensor, and the number of operating compressors is controlled in accordance with the detected increase rate or decrease rate. In other words, the rate of increase or decrease in pressure in the tank changes according to the amount of compressed air consumed from the tank. Therefore, the amount of compressed air consumed is estimated from the rate of increase or decrease in pressure, and the compressor is operated. The number of units was controlled.

JP 2007-120497 A

  By the way, a tank may be added or changed depending on the use state of compressed air. Also, the number of compressors installed may change. For example, when a tank is added or changed, the total capacity of all tanks is changed as compared to before adding a tank. At this time, since the control device calculates the consumption amount of compressed air using the total capacity of the tank, the installation operator etc. sets the setting information of the installation environment each time the total capacity of the tank changes. I had to start over.

  Patent Document 1 discloses a configuration in which the entire capacity of the tank is automatically detected by stopping the supply of compressed air from the tank to the outside. However, in this case, it is necessary to temporarily stop the supply of compressed air in order to increase the number of tanks. For example, in the usage situation where compressed air is always used as in factory equipment, the entire factory equipment is also stopped. As a result, there was a problem that convenience was low.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a control device for a gas compression device capable of adding a tank or the like while using compressed gas. .

  In order to solve the above-described problems, the present invention provides a gas compression device that compresses and discharges a gas, a tank that stores compressed gas by the gas compression device, and a pressure detection unit that detects a pressure in the tank. The supply amount of compressed gas is increased when the pressure in the tank detected by the pressure detection means reaches a predetermined lower limit value, and the supply amount of compressed gas is decreased when the pressure reaches the upper limit value. In the control device of the gas compression device comprising the control means for controlling the gas compression device as described above, the control means is configured such that the pressure in the tank detected by the pressure detection means is determined from the predetermined first pressure value. From the rate of increase until reaching a predetermined second pressure value higher than the first pressure value, and the rate of decrease until reaching the first pressure value from the second pressure value, the capacity of the tank and the consumption of compressed gas, To calculate It is characterized by changing the upper limit value based on the calculation result.

  According to the present invention, it is possible to add or change a tank while using compressed gas.

It is a whole lineblock diagram showing the air compression device by an embodiment of the invention. It is a flowchart which shows the number control process by the air compressor in FIG. It is a flowchart which shows the change process of the upper limit by the air compressor in FIG. It is a flowchart which shows the calculation process of the tank capacity | capacitance and air consumption in FIG. It is explanatory drawing which shows the statistical distribution of pressure decrease time, pressure increase time, air consumption, and tank capacity when the processing of tank capacity and air consumption is performed. It is a characteristic diagram which shows time changes, such as the pressure in a tank, power consumption, the supply amount of compressed air, about the case where the number control processing by embodiment and the prior art is used. It is explanatory drawing which shows the case where the increase rate and decrease rate of the pressure of a tank are measured as a 1st modification of this invention. It is explanatory drawing which shows the case where a pressure increase time and a pressure decrease time are measured as a 2nd modification of this invention.

  Hereinafter, a case where the gas compression apparatus according to the embodiment of the present invention is configured by using four compressors that individually supply compressed air to a tank will be described as an example and described in detail with reference to the accompanying drawings.

  First, in FIG. 1, the air compressor 1 is comprised by the four compressors 2A-2D. Here, the compressor 2A includes an electric motor 3A, a compressor main body 4A driven by the electric motor 3A, and a temporary storage tank 5A for temporarily storing compressed air discharged from the compressor main body 4A. It is configured. The other compressors 2B to 2D are also configured by electric motors 3B to 3D, compressor main bodies 4B to 4D, and temporary storage tanks 5B to 5D, respectively, similarly to the compressor 2A. The compressors 2A to 2D all have the same discharge capacity Fa to Fd (for example, Fa to Fd = 605 (NL / min)), for example.

  Further, pressure sensors 6A to 6D for detecting internal pressure are attached to the temporary storage tanks 5A to 5D. Further, the compressors 2A to 2D are respectively provided with control circuits 7A to 7D for controlling the operation and stop of the electric motors 3A to 3D. The control circuits 7A to 7D have various communication functions for performing wired communication or wireless communication, for example, and communicate with each other through the communication function.

  In addition, four types of information such as model information, operation information, abnormality information, and environment setting information are transmitted between the control circuits 7A to 7D by communication. As a result, the control circuits 7A to 7D share these four types of information.

  At this time, the model information includes the capacity (kW) of the electric motors 3A to 3D, the discharge flow rate (NL / min) of the compressor bodies 4A to 4D, the capacity (L) of the temporary storage tanks 5A to 5D, and the initial temporary storage tank. It is a temporary storage tank filling time (sec) for filling 5A to 5D.

The operation information includes general operation time (min) of each compressor 2A to 2D, ON / OFF frequency (times), tank capacity Vall (L) described later, and an average value Ave (Vall) (L), The pressure increase time t _on (sec), the pressure decrease time t _off (sec), the air consumption No (L), the average value Ave (No) (L), and the like. The abnormality information is information that hinders the operation of the compressors 2A to 2D, such as a thermal trip error and a dryer error.

  Further, the environment setting information includes an initial value Vall (0) (L) of a tank capacity Vall, which will be described later, the number of compressors 2A to 2D (units) to be controlled, and the master switching time until the master and the slave are switched. (Min), a lower limit value Pmin (MPa) and an upper limit value Pmax (MPa) of the pressure P in the tank 8. The environment setting information is input by connecting a dedicated input terminal (not shown) to the control circuits 7A to 7D, for example, when an installation worker or the like installs the compressors 2A to 2D. At this time, the environment setting information includes information such as IDs (identification numbers) and master / slave settings of the compressors 2A to 2D for communication.

  The control circuits 7A to 7D adopt a distributed control method, and control the operation and stop of the compressors 2A to 2D by setting one of them as a master (main machine) and the remaining three as slaves (slave machines). To do. Thereby, the control circuits 7A to 7D constitute control means, and as will be described later, the pressure P and the pressure change value ΔP of the tank 8, the air consumption No calculated by the control circuits 7A to 7D, and the tank capacity Vall. The number control process for increasing or decreasing the number of operating compressors 2A to 2D according to the average value Ave (Vall) of (L) is performed.

  The tank 8 collects and stores the compressed air discharged from the temporary storage tanks 5A to 5D. The tank 8 is connected to the temporary storage tanks 5A to 5D through the discharge pipes 9A to 9D, and check valves 10A to 10D are provided in the middle of the discharge pipes 9A to 9D. An output pipe 11 having a take-off valve 12 is attached to the tank 8. Thus, the tank 8 is connected to an external pneumatic device (not shown) via the output pipe 11 and supplies compressed air to the pneumatic device by opening the take-off valve 12. Is.

  The pressure sensor 13 constitutes a pressure detection means connected to the tank 8. The pressure sensor 13 detects the pressure P of the compressed air in the tank 8 and outputs a pressure signal corresponding to the pressure P.

  The temperature sensor 14 constitutes temperature detection means connected to the tank 8. The temperature sensor 14 detects the temperature T of the compressed air in the tank 8 and outputs a temperature signal corresponding to the temperature T.

  And pressure sensor 13 and temperature sensor 14 are connected to control circuits 7A-7D of compressors 2A-2D, respectively. Thereby, any of the control circuits 7A to 7D can detect the pressure P and the temperature T in the tank 8.

  The pressure sensor 13 and the temperature sensor 14 are not limited to being connected to all the control circuits 7A to 7D, but may be connected to only the control circuit 7A, for example. In this case, for example, by connecting the control circuits 7A to 7D in a loop, pressure signals and temperature signals are also output to the remaining control circuits 7B to 7D.

  The air compressor 1 according to the present embodiment has the above-described configuration. Next, referring to FIGS. 1 and 2, the number of compressors 2A to 2D operated according to the pressure P of the tank 8 and the like. The number control process to increase or decrease will be described.

  The number control process shown in FIG. 2 is performed every predetermined sampling period Δt (for example, Δt = 100 msec).

  First, in step 1, using the pressure signal from the pressure sensor 13, the current pressure P (t) of the tank 8 is measured at a constant sampling period Δt. In step 2, the temperature T of the compressed air in the current tank 8 is measured at a constant sampling period Δt using the temperature signal from the temperature sensor 14.

  Next, in step 3, as shown in the following equation 1, the difference between the current pressure P (t) and the previous pressure P (t-1) is calculated to obtain a pressure change value ΔP.

  Next, in step 4, a predetermined change based on the equation of state using the pressure change value ΔP, temperature T, sampling period Δt, average value Ave (Vall) of tank capacity Vall, supply amount F of compressed air, gas constant R and the like. The consumption amount N of compressed air is calculated by performing arithmetic processing. At this time, the tank capacity Vall is an equivalent total capacity in which all the capacities of the tank 8 and the temporary storage tanks 5A to 5D are added and the capacity based on the average value Ave (No) of the air consumption No is also added. The average value Ave (Vall) is an arithmetic average obtained by the number of calculations of the tank capacity Vall as will be described later. The average value Ave (Vall) of the tank capacity Vall is calculated by the tank capacity and air consumption calculation process shown in FIG. The supply amount F of compressed air is a value obtained by adding the discharge capacities Fa to Fd of the compressors in operation among the compressors 2A to 2D.

  Next, in step 5, it is determined whether at least one of the compressors 2A to 2D is in operation. If “YES” is determined in step 5, since compressed air is being supplied into the tank 8, whether or not the pressure P of the tank 8 is equal to or higher than the upper limit value Pmax (P ≧ Pmax) in step 6. Determine whether. In step 6, an upper limit value Pmax determined by an upper limit value changing process shown in FIG. 3 to be described later is read to determine the pressure P.

  And when it determines with "YES" at step 6, since the pressure P has become more than the upper limit Pmax, it moves to step 7 and stops operation | movement of all the compressors 2A-2D, and returns at step 10.

  On the other hand, when it is determined “NO” in step 6, the pressure P has not reached the upper limit value Pmax. For this reason, it moves to step 9 and calculates | requires the optimal operating number of compressor 2A-2D according to the consumption N of compressed air. Specifically, the optimum operating number of the compressors 2A to 2D is set as small as possible within a range where the supply amount F of compressed air exceeds the consumption amount N in order to reduce the power consumption. Then, the control circuits 7A to 7D drive the compressors 2A to 2D corresponding to the number of operating units. Thereafter, the process proceeds to step 10 and returns.

  Further, when “NO” is determined in step 5, since all the compressors 2 </ b> A to 2 </ b> D are stopped, for example, after the pressure P has reached the upper limit value Pmax, the pressure P of the tank 8 is determined in step 8. It is determined whether or not it is lower than the lower limit value Pmin (P <Pmin).

  When it is determined as “YES” in step 8, the process proceeds to step 9 to obtain the optimum number of the compressors 2 </ b> A to 2 </ b> D according to the compressed air consumption N, and the compressor 2 </ b> A corresponding to this number of operations. Drive ~ 2D. Thereafter, the process proceeds to step 10 and returns.

  On the other hand, when “NO” is determined in step 8, the pressure P of the tank 8 is higher than the lower limit Pmin, and the compressed air that can be supplied to the outside remains in the tank 8. Therefore, all the compressors 2A to 2D are held in a stopped state, and the process proceeds to step 10 and returns.

  Next, an upper limit value changing process for changing the upper limit value Pmax used in the number control process will be described with reference to FIG. Note that the upper limit value changing process in FIG. 3 is interrupted in the middle of the number control process, for example, by a user's operation for every fixed time (every several hours) or for adding a tank. When the upper limit value Pmax is changed, the result is reflected in the number control process.

  First, in step 11, it is determined whether or not the operation of the air compressor 1 is started. And when it determines with "NO" at step 11, it waits in the state as it is. On the other hand, if “YES” is determined in the step 11, the process proceeds to a step 12 to perform a tank capacity and air consumption calculation process shown in FIG.

  Next, in step 13, it is determined whether or not the tank capacity Vall calculated in step 12 is larger than the initial value Vall (0) (Vall> Vall (0)) as a determination capacity. At this time, the initial value Vall (0) is, for example, the sum of the capacities of the temporary storage tanks 5A to 5D, and is input in advance to the control circuits 7A to 7D by, for example, an installation worker. The capacity for determination is not limited to the initial value Vall (0), but may be a value obtained by adding the capacity of the tank 8 to the initial value Vall (0).

  If "NO" is determined in the step 13, the process proceeds to a step 14 to determine whether or not the air consumption No calculated in the step 12 is larger than a predetermined threshold NT (No> NT). At this time, the threshold value NT is determined in consideration of the initial value Vall (0), the discharge capacities Fa to Fd, etc., and is set to, for example, the same value as the discharge capacity for one unit. And when it determines with "YES" at step 14, since the air consumption No is larger than the threshold value NT, the state as it is is maintained and it transfers to step 18. The threshold value NT is not limited to the discharge capacity for one unit, but is set as appropriate in a range smaller than the discharge capacity for four units.

  On the other hand, if “NO” is determined in step 14, the air consumption No is smaller than the threshold value NT, so it is considered that the compressed air will not run short even if the upper limit value Pmax is lowered. Therefore, the process proceeds to step 15 where the upper limit value Pmax is lowered by a predetermined value α. Thereby, the compressors 2A to 2D can be driven at a lower pressure than before the change of the upper limit value Pmax, and the power consumption can be reduced. Note that the predetermined value α is, for example, about 5% of the pressure difference between the upper limit value Pmax (0) and the lower limit value Pmin in the initial state. The value Pmax can be reduced. Further, the predetermined value α may be set as appropriate according to the usage state of the air compressor 1, and further, a lower limit of the upper limit value Pmax may be determined. Further, the upper limit value Pmax may be reduced by other calculations. Then, after the process of step 15 is completed, the process proceeds to step 18.

  If “YES” is determined in step 13, the process proceeds to step 16, where it is determined whether the air consumption No is larger than a predetermined threshold NT (No> NT) as in step 14. If "YES" is determined in the step 16, the air consumption amount No is larger than the predetermined threshold value NT, so that the state is maintained as it is and the process proceeds to the step 18.

  On the other hand, when “NO” is determined in Step 16, the tank capacity Vall is larger than the capacity for determination (initial value Vall (0)), and the air consumption amount No is smaller than the threshold value NT. For this reason, the process proceeds to step 17 and the upper limit value Pmax is lowered using the following equation (2). That is, as shown in the equation (2), the upper limit value Pmax (0) in the initial state is determined according to the ratio between the average value Ave (Vall) of the tank capacity obtained by the calculation in step 12 and the initial value Vall (0). And the pressure difference between the lower limit Pmin. Then, after the process of step 17 is completed, the process proceeds to step 18.

  In step 18, it is determined whether or not the air compressor 1 has stopped operating. If "NO" is determined in the step 18, the processes after the step 12 are repeated. On the other hand, if “YES” is determined in step 18, the process proceeds to step 19 and returns.

  Next, the processing for calculating the tank capacity and the air consumption in step 12 in FIG. 3 will be described with reference to FIG.

  First, in step 21, a counter n for storing the number of calculations is initialized to 1. In step 22, the compressor P is stopped so that the pressure P increases to the upper limit value Pmax (0) and all the compressors 2A to 2D are stopped. That is, in step 22, the pressure P of the tank 8 is measured using the pressure signal from the pressure sensor 13, and if the pressure P does not reach the upper limit value Pmax (0), for example, all the compressors 2A to 2D are connected. The pressure P is driven to reach the upper limit value Pmax (0). In the present embodiment, the upper limit value Pmax (0) is used as the predetermined second pressure value. When the pressure P reaches the upper limit value Pmax (0), all the compressors 2A to 2D are stopped, and the process proceeds to step S23.

  In step 23, using the temperature signal from the temperature sensor 14, the temperature T (Pmax) of the compressed air in the tank 8 immediately after the compressors 2A to 2D stop at the upper limit value Pmax (0) is measured.

Next, in step 24, the stop time from when the compressors 2A to 2D stop until the pressure P of the tank 8 decreases to the lower limit value Pmin and restarts is measured as the pressure decrease time t _off (n). In the present embodiment, the lower limit value Pmin is used as the predetermined first pressure value. At this time, as the pressure P decreases, the temperature of the compressed air in the tank 8 also decreases. For this reason, in step 25, immediately before the compressors 2A to 2D are restarted, the temperature T (Pmin) of the compressed air remaining in the tank 8 is measured.

Next, in step 26, using the pressure decrease time t _off (n) measured in step 24, an arithmetic average corresponding to the number of times of the counter n is calculated as shown in the following equation (3), An average value Ave ( _toff ) is obtained.

  Next, in step 27, as shown in the following equation (4), the set upper limit value Pmax (0) and lower limit value Pmin and the measured temperature T (Pmax) and temperature T (Pmin) are used. The current air consumption No (n) is obtained. In addition, the tank capacity Vall (n−1) in the equation 4 indicates the tank capacity Vall calculated one time before, and R indicates a gas constant. When the counter n is the initial value (n = 1), the tank capacity Vall (n−1) is the sum of the capacities of the temporary storage tanks 5A to 5D as the initial value Vall (0).

  Next, in step 28, as in the equation (3), the air consumption amount No (n) calculated in step 27 is an arithmetic average corresponding to the number of times of the counter n as shown in the following equation (5). To obtain an average value Ave (No).

  Next, in step 29, the compressor P is operated so that the pressure P decreases to the lower limit value Pmin and the compressors 2A to 2D are all operated. That is, in step 29, the pressure P of the tank 8 is measured using the pressure signal from the pressure sensor 13, and if the pressure P does not reach the lower limit value Pmin, for example, all the compressors 2A to 2D are stopped. Hold and wait until the pressure P reaches the lower limit Pmin. When the pressure P reaches the lower limit value Pmin, all the compressors 2A to 2D are activated, and the routine proceeds to step 30.

In step 30, the operation time from when all the compressors 2A to 2D are started to when they are stopped again is measured as the pressure increase time t _on (n). Here, the pressure P in the tank 8 is pressurized until reaching the upper limit value Pmax set again by the operation of the compressors 2A to 2D.

Then, in step 31, similarly to the equation of equation 3, the pressure increase time t _on (n) measured in step 30 is used to correspond to the number of times of the counter n as shown in the equation of equation 6 below. An arithmetic average is calculated to obtain an average value Ave (t _on ).

Next, in step 32, as shown in the following equation (7), calculation is performed using the set upper limit value Pmax (0) and lower limit value Pmin and the measured temperature T (Pmin), and the tank capacity Vall is calculated. (N) is obtained. The initial value t _on (0) in Equation 7 is in a state where the air consumption No is 0 (No = 0), that is, when the tanks 8 are not connected to the outside and the compressors 2A to 2D are operated alone, This is a certain time required to raise the temporary storage tanks 5A to 5D from the lower limit value Pmin to the upper limit value Pmax. For this reason, the first term on the right side of the equation (7) represents the current tank from the initial value Vall (0) of the tank capacity Vall according to the ratio between the pressure increase time t _on (n) and the initial value t _on (0). The capacity Vall (n) is estimated. Here, since the average value Ave (t _on ) becomes longer in accordance with the air consumption No, the tank capacity Vall (n) is estimated by adding the air consumption No as a part of the capacity. .

  In step 33, similarly to the equation (3), an arithmetic average corresponding to the number of counters n is calculated using the tank capacity Vall (n) as shown in the following equation (8). The value Ave (Vall) is obtained.

  Then, after the value of the counter n is incremented by 1 in step 34, the process proceeds to step 35. In step 35, it is determined whether or not the current value of the counter n is greater than a specific number of times, for example, 30 times. If it is determined “NO”, the arithmetic processing from step 22 is repeated. At this time, the next air consumption No (n + 1) is calculated using the tank capacity Vall (n) calculated this time. Note that the specific number of times used in step 35 is not limited to 30 and is appropriately set in consideration of the estimation accuracy of the average value Ave (No) of the air consumption No and the average value Ave (Vall) of the tank capacity Vall. Is.

  On the other hand, if “YES” is determined in step 35, the process proceeds to step 36 and returns.

  In the above calculation process, the calculation process method for alternately calculating the tank capacity Vall and the air consumption No has been described, but the capacity of the tank 8 connected to the compressors 2A to 2D does not change frequently. Considering this, the calculation frequency of the tank capacity Vall (n) in step 32 is sufficiently smaller than the calculation of the air consumption No (n) in step 27 (for example, about once a day). May be.

Moreover, in the said embodiment, when the pressure P reached | attained the lower limit Pmin in the operation process of the compressor of step 29, it was set as the structure which drive | operates all the compressors 2A-2D. However, the present invention is not limited to this. For example, the number of operating compressors 2A to 2D may be reduced within a range exceeding the air consumption No (n) calculated in step 27. In this case, depending on the number of operating compressor 2A~2D initial value t _on (n) changes, since the number of operating units the initial value t _on (n) in accordance with decreases increases in number 7, Ave (t _on ) / t _on (0) is multiplied by a coefficient corresponding to the number of operating units to correct the tank capacity Vall (n).

In the embodiment, the air consumption No (n) is calculated from the pressure decrease time t _off (n) and the tank capacity Vall (n−1), and the calculated air consumption No (n) and the pressure increase time are calculated. A new tank capacity Vall (n) is calculated from t _on (n). However, the present invention is not limited to this. For example, the tank capacity Vall (n) is calculated from the pressure decrease time t _off (n) and the air consumption No (n), and the calculated tank capacity Vall (n) and the pressure increase time are calculated. The order may be changed so that a new air consumption No (n + 1) is calculated from t _on (n).

When the tank volume and air consumption calculation processes are performed as described above, the measured and calculated pressure decrease time t _off (n), pressure increase time t _on (n), air consumption No (n), The tank capacity Vall (n) is totaled and the statistical distribution is graphed as shown in FIG.

  Here, the average value Ave (Vall) of the tank capacity Vall is calculated as a part of the tank capacity Vall by the capacity of the pipe and the average consumption of the compressed air, that is, the average value Ave (No). . For this reason, when the compressors 2A to 2D are operated, the operation time of the compressors 2A to 2D is longer than the case where the tank capacity Vall is simply stored in the control circuits 7A to 7D. Since the air supply amount F and the air consumption amount No are controlled to be close to each other, the power consumption of the air compressor 1 can be reduced. Moreover, the mechanical load to the compressors 2A to 2D can be reduced by reducing the number of activations.

  Further, it is not necessary to manually store the information of the tank capacity Vall in the control circuits 7A to 7D. Therefore, for example, as shown by a two-dot line in FIG. 1, even when the expansion tank 15 is connected to or separated from the tank 8 by the valve 16, the tank capacity Vall can be calculated and updated. . As a result, even when the tank capacity Vall is changed according to the air consumption No or when the tank 15 is connected or disconnected (opening or closing the valve 16), the installation operator does not update the information automatically. Thus, the value of the tank capacity Vall can be changed.

  Further, the case where the upper limit value Pmax is made constant as in the prior art is compared with the case where the upper limit value Pmax is changed as in the present embodiment. The result is shown in FIG. Note that the solid line in FIG. 6 indicates the pressure P in the tank 8 when the upper limit value Pmax is changed and the number control process is performed as in the present embodiment. On the other hand, the broken line in FIG. 6 indicates the pressure P in the tank 8 or the like when the number control process is performed with the upper limit value Pmax being constant as in the prior art.

  As shown in FIG. 6, in the case of the prior art, even after the tank 15 is added, the upper limit value Pmax is not changed and becomes the same value as before the addition. The tank capacity Vall is also fixed to the value before the change unless manually input by the installation operator. For this reason, in the prior art, even when the pressure change becomes mild due to the addition of the tank 15, the consumption N of the compressed air is calculated based on the tank capacity Vall before the change, so the pressure P reaches the lower limit value Pmin. Then, a small number of operating units (for example, one) of compressors are driven according to the pressure change. However, even if the operation of the compressor is started, an increase in pressure commensurate with the number of compressors operated is not detected due to the addition of the tank 15. For this reason, the number of operating compressors increases during the pressure increase. Then, when the pressure P reaches the upper limit value Pmax, the compressor stops.

  On the other hand, in the present embodiment, for example, after adding the tank 15 in FIG. 1, the tank capacity Vall with the capacity of the tank 15 is calculated, and the upper limit value Pmax is changed based on the calculation result of the tank capacity Vall. . More specifically, when the tank 15 is added, the tank capacity Vall becomes larger than before the addition, so that the capacity of the compressed air stored in the tank 8 and the tank 15 also increases. Therefore, the control circuits 7A to 7D execute the upper limit value changing process to lower the upper limit value Pmax. As a result, the compressors 2A to 2D are driven at a low pressure close to the lower limit value Pmin compared to the upper limit value Pmax before the change, so that the power consumption is reduced as compared to before the expansion. When powers are compared in FIG. 6, the power according to the present embodiment is lower than that of the prior art, and a power saving effect is obtained (the hatched pattern portion in FIG. 6).

Thus, according to the present embodiment, the control circuits 7A to 7D allow the pressure increase time corresponding to the rate of increase until the pressure P in the tank 8 detected by the pressure sensor 13 reaches the upper limit value Pmax from the lower limit value Pmin. The air consumption No and the tank capacity Vall can be calculated based _on t _on and the pressure reduction time t _off corresponding to the rate of decrease from the upper limit value Pmax to the lower limit value Pmin. For this reason, when the tank capacity Vall increases, it is possible to lower the upper limit value Pmax at which the tank capacity is stopped, and to reduce the number of operating compressors 2A to 2D. Thereby, the supply amount F of compressed air can be adjusted according to the air consumption No and the tank capacity Vall. As a result, since the air compressor 1 can suppress the discharge of unnecessary compressed air exceeding the air consumption No, the power consumption of the air compressor 1 can be reduced.

  In addition, since the air consumption No and the tank capacity Vall can be calculated easily without stopping the measurement of the supply of compressed air to the outside, the use of the air compressor 1 is interrupted. There is no need to add or change tanks.

  Further, since it is not necessary for the installation operator to set the tank capacity Vall from the outside, the user can easily add a tank or change the capacity. Furthermore, even when the tank capacity Vall is changed, the upper limit value Pmax can be set low according to the air consumption amount No. As a result, the compressors 2A to 2D can be driven in a state where the pressure P is low, and the power consumption can be further reduced. Therefore, by using the tank capacity Vall according to the air consumption No, it is possible to suppress power consumption according to the busy season.

Further, the calculated information such as the air consumption No, the tank capacity Vall, and the operation frequency (t _on / t _off ) of the compressors 2A to 2D may be registered in the storage means (for example, EEPROM). Good. In this case, by confirming the air consumption No, the operation frequency (t _on / t _off ), and the calculated tank capacity Vall, the installation operator can grasp the supply capacity and the operation status of the air compressor 1, for example, the user On the other hand, it is possible to propose a change to the optimum equipment for the user, such as whether the compressors 2A to 2D and the tank 8 need to be changed or expanded.

In the above embodiment, the air consumption No and the tank capacity Vall are calculated based _{on the} pressure decrease time _toff and the pressure increase time ton. However, when the rate of decrease of the tank pressure per time is large, the pressure decrease time t _off becomes short, and when the rate of decrease is small, the pressure decrease time t _off becomes long. Similarly, when the increase rate of the tank pressure per time is large, the pressure increase time t _on becomes short, and when the increase rate is small, the pressure increase time t _on becomes long. Thus, there is a fixed correspondence between the rate of decrease of pressure P and the pressure decrease time t _off, and there is also a fixed relationship between the rate of increase of pressure P and the pressure increase time t _on . Therefore, the air consumption No and the tank capacity Vall are substantially calculated according to the change rate (increase rate and decrease rate) of the pressure P.

In the above embodiment, the tank capacity Vall and the air consumption No are calculated using the operation time (pressure increase time t _on ) and the stop time (pressure decrease time t _off ) of the compressors 2A to 2D. However, the present invention is not limited to this, and as shown in the first modification of FIG. 7, the calculation is performed using the increase rate ΔPu and decrease rate ΔPd of the pressure P in the tank 8 at a specific sampling period Δt0. Alternatively, as shown in the second modified example of FIG. 8, a calculation may be performed using the pressure increase time Δt _on and the pressure decrease time Δt _off at a predetermined pressure difference ΔP0. In this case, the first pressure for calculating the tank capacity Vall and the air consumption No required to obtain the pressure difference ΔP0 without increasing or decreasing the pressure between the upper limit value Pmax and the lower limit value Pmin. A value and a second pressure value may be set.

  In the above embodiment, the case where the temporary storage tanks 5A to 5D are provided is described as an example. However, the temporary storage tanks 5A to 5D are not necessarily provided, and only the tank 8 may be provided. In this case, all devices may be housed in one package and controlled by a single control board.

  Moreover, in the said embodiment, the air compressor 1 shall be comprised by four compressor 2A-2D. However, the present invention is not limited to this. For example, the air compressor may be configured by one, two, or three compressors, or may be configured by five or more compressors. When the air compressor is composed of a single compressor, the compressor is stopped when the tank pressure reaches the upper limit, and the compressor is stopped when the tank pressure reaches the lower limit, not the unit control. Pressure open / close control is performed to restart the machine.

  Moreover, in the said embodiment, the air compressor 1 shall be comprised by four compressor 2A-2D. However, the present invention is not limited to this. For example, the air compressor may be configured using a single variable displacement compressor. Moreover, it is good also as a structure which uses a variable displacement pump as an air compressor.

  Moreover, in the said embodiment, it was set as the structure which performs the number control process of a distributed system using control circuit 7A-7D. However, the present invention is not limited to this. For example, a control device that centrally manages the compressors 2A to 2D separately from the control circuits 7A to 7D is provided, and a centralized number control process is performed using the control device. It is good also as composition which performs.

  Moreover, although the air compressor 1 by the said embodiment made the discharge capacity Fa-Fd of four compressors the same, you may use the compression from which a discharge capacity differs not only for this but for every compressor. In this case, finer control is possible by combining the compressors.

  Moreover, compressors, such as a reciprocating machine, a screw, a scroll, can be used as a compressor of this invention, and you may use combining these compressors. Furthermore, it is good also as a booster type compressor which pressurizes and discharges compressed air.

  Furthermore, in the above-described embodiment, an example in which the compressor is operated or stopped is shown. However, in a compressor capable of unload operation such as reciprocation, when the number of operating units is decreased, the unload is performed for a predetermined time. You may comprise so that it may drive | operate and may stop after that.

  Furthermore, in the said embodiment, although the example of the air compressor which compresses air was shown, it is good also as a structure used for the gas compression apparatus which compresses gas, such as not only this but nitrogen and oxygen.

1 Air compressor (gas compressor)
2A to 2D compressor 7A to 7D Control circuit (control means)
8, 15 Tank 13 Pressure sensor (pressure detection means)
14 Temperature sensor (temperature detection means)

Claims (3)

A gas compression device that compresses and discharges the gas; a tank that stores compressed gas by the gas compression device; a pressure detection unit that detects a pressure in the tank; and a tank in the tank that is detected by the pressure detection unit. Control means for controlling the gas compression device to increase the supply amount of the compressed gas when the pressure reaches a predetermined lower limit and to decrease the supply amount of the compressed gas when the pressure reaches the upper limit. In the control device of the gas compression device provided,
The control means includes a rate of increase until the pressure in the tank detected by the pressure detection means reaches a predetermined second pressure value higher than the first pressure value from a predetermined first pressure value, and the second pressure. A gas compression device that calculates a capacity of the tank and a consumption amount of compressed gas from a rate of decrease until reaching the first pressure value, and changes the upper limit value based on the calculation result Control device. The control means calculates the consumption amount of compressed gas based on the rate of decrease in pressure in the tank detected by the pressure detection means and the capacity of the tank calculated by the calculation,
2. The gas according to claim 1, wherein the capacity of the tank is calculated again based on the rate of increase in pressure in the tank detected by the pressure detection means and the consumption of compressed gas calculated by the calculation. Control device for the compression device. The gas compression device includes a plurality of compressors,
The control device for a gas compression device according to claim 1 or 2, wherein the control means is configured to change the number of operating compressors in accordance with the calculated capacity of the tank and consumption of compressed gas.

Images