JP6078748B2 - Suction system and suction method - Google Patents

Description

  The present invention includes a suction system including a first suction device and a second suction device and configured to be able to suck a gas from a suction target in a state in which both suction devices are switched between a parallel connection state and a serial connection state, and The present invention relates to a suction method for sucking a gas from a suction target using such a suction system.

  As a suction system of this type, a vacuum exhaust device is disclosed in Patent Document 1 below. This vacuum evacuation device includes a pair of vacuum pumps and three valves for switching both vacuum pumps to either a parallel connection state or a series connection state. In this vacuum exhaust apparatus, first, both vacuum pumps are operated, and the open / close state of each valve is changed to switch both vacuum pumps to a parallel connection state. At this time, air is sucked from the exhausted device (suction target) by both vacuum pumps, and the inside of the pipe connecting the exhausted device and both vacuum pumps is in a vacuum state.

  Next, when the vacuum pressure in the pipe reaches the specified pressure (when the vacuum pressure in the pipe is high enough to suck air in the parallel connection state), both vacuum pumps are turned on. While maintaining the operated state, the open / close state of each valve is changed to switch both vacuum pumps to a serial connection state. At this time, the air discharged from the discharge port of the upstream vacuum pump is sucked by the downstream vacuum pump and the exhaust resistance of the upstream vacuum pump is reduced, so that the suction efficiency of the upstream vacuum pump is reduced. Will improve. As a result, even if the inside of the piping is at a somewhat high vacuum pressure due to the operation in the parallel connection state, it is possible to suck more air by both the vacuum pumps switched to the serial connection state, and thus the operation in the parallel connection state. The vacuum pressure in the pipe rises to a sufficiently high vacuum pressure than when it was.

Japanese Utility Model Publication No. 4-119373 (page 3-5, Fig. 1-3)

  However, the conventional vacuum exhaust apparatus has the following problems to be solved. That is, in the conventional evacuation apparatus, by operating both vacuum pumps in a parallel connection state at the start of operation, a large amount of air is sucked per unit time by both vacuum pumps, and a certain vacuum pressure is set in the pipe in a short time. After that, a configuration and a method are adopted in which both vacuum pumps are switched to a serial connection state and air is further sucked to further increase the vacuum pressure in the pipe. On the other hand, there is a demand for reducing the running cost of this type of suction system.

  In this case, power consumption can be reduced by adopting a small vacuum pump as the both vacuum pumps in the above-described vacuum exhaust system or by reducing the number of rotations of both vacuum pumps by adopting a variable rotation speed type vacuum pump. The running cost can be reduced by reducing the amount. However, since a small vacuum pump has a low suction capability, the amount of air that can be sucked per unit time in a parallel connection state decreases, making it difficult to increase the vacuum pressure in the pipe in a short time, and in series. It is difficult to suck a sufficient amount of air that can sufficiently increase the vacuum pressure in the pipe in the connected state. Even if a vacuum pump with a high suction capacity is used, if the number of rotations of both vacuum pumps is reduced in a parallel connection state, the amount of air that can be sucked per unit time will decrease and the vacuum pressure in the pipe will be reduced. It becomes difficult to raise in a short time, and when the number of rotations of both vacuum pumps is reduced in a serial connection state, it becomes difficult to suck a sufficient amount of air that can sufficiently raise the vacuum pressure in the pipe. . Therefore, in a suction system such as a conventional vacuum exhaust device, the vacuum pressure in the pipe is increased in a short time in the parallel connection state, and a sufficient amount of air can be sucked from the suction target in the serial connection state. There is a problem that it is difficult to reduce the running cost.

  The present invention has been made in view of such problems, while raising the vacuum pressure in the pipe in a short time in the parallel connection state and allowing a sufficient amount of air to be sucked from the suction target in the serial connection state. The main object is to provide a suction system and a suction method capable of sufficiently reducing the running cost.

In order to achieve the above object, the suction system according to claim 1 includes a first suction device and a second suction device, and is configured to be able to suck a gas from a suction target by the both suction devices. Connected in parallel to the suction target, the suction port of the first suction device is connected to the suction target, and the suction port of the second suction device is connected to the suction target of the first suction device. A suction system configured to be switchable to any one of a serial connection state connected to an outlet, and a control device for controlling the number of rotations of both the suction devices, and a suction device with variable rotation speed as the both suction devices. and a section, wherein the control unit is true in the pipe in which the two suction device connects the suction system to the suction target in a state that has been switched to the series connection state from the parallel connection state State so as to reduce the rotational speed of the second suction device when the first condition to rise to a first vacuum pressure pressure defined previously is met, and to reduce the rotational speed of the second suction device When the second condition that the vacuum pressure in the pipe is reduced to a predetermined second vacuum pressure lower than the first vacuum pressure is satisfied, the rotational speed of the first suction device is increased.

  The suction system according to claim 2, wherein in the suction system according to claim 1, the control unit changes the rotation speed of the second suction device from the parallel connection state to the series connection when the first condition is satisfied. The number of revolutions is reduced below that at the time of switching to the state.

  A suction system according to a third aspect of the present invention is the suction system according to the first or second aspect, wherein the control unit changes the rotational speed of the first suction device from the parallel connection state when the second condition is satisfied. The number of revolutions is increased from that at the time of switching to the serial connection state.

The suction method according to claim 4 comprises a first suction device having a variable rotation speed type and a second suction device having a variable rotation speed type, and is configured to be able to suck a gas from a suction target by the suction devices. A parallel connection state in which the suction ports of both suction devices are connected to the suction target, the suction port of the first suction device is connected to the suction target, and the suction port of the second suction device is the first suction. A suction method in which the gas is sucked from the suction target by a suction system configured to be switchable to any one of a serial connection state connected to a discharge port of the device, wherein the both suction devices are the first condition to be raised to a first vacuum pressure vacuum pressure in the pipe connecting the suction system to the suction target in a state that has been switched to the series connection state is defined in advance Mitsuru So as to reduce the rotational speed of the second suction device when it is, it is lower predefined than vacuum pressure of the first vacuum pressure in the pipe in a state in which to reduce the rotational speed of the second suction device When the second condition of lowering to the second vacuum pressure is satisfied, the rotational speed of the first suction device is increased.

  The suction method according to claim 5 is the suction method according to claim 4, wherein the rotation speed of the second suction device is switched from the parallel connection state to the series connection state when the first condition is satisfied. The number of rotations is reduced below.

  The suction method according to claim 6 is the suction method according to claim 4 or 5, wherein when the second condition is satisfied, the rotational speed of the first suction device is switched from the parallel connection state to the series connection state. Higher than the number of revolutions at the time.

According to the suction system according to claim 1 and the suction method according to claim 4, when the first condition is satisfied in the serial connection state, the rotational speed of the second suction device is reduced, and the second suction device by increasing the rotational speed of the first suction device when the second condition is satisfied in a state in which to reduce the rotational speed, so that a higher vacuum pressure than the parallel connection state by switching to series connection state It is possible to sufficiently reduce the total power consumption of both suction devices in the serial connection state by reducing the rotation speed of the second suction device while allowing a sufficient amount of air to be sucked from the suction target. In addition, when the rotation speed of the first suction device is increased in order to suck more air from the suction target in the serial connection state, both suctions are performed by the amount that the rotation speed of the second suction device is decreased. apparatus It is possible to avoid a situation where the total sum of the power consumption is excessively large. Thereby, the running cost can be sufficiently reduced while allowing a sufficient amount of air to be sucked from the suction target so that a sufficiently high vacuum pressure is obtained in the series connection state. Furthermore, unlike adopting a small pump or reducing the rotational speed of both suction devices in the parallel connection state, the rotational speed of both suction devices in the parallel connection state is set as necessary immediately after the start of operation, that is, By setting the rotation speed to a sufficiently high number, the vacuum pressure in the pipe can be increased in a short time.

  According to the suction system according to claim 2 and the suction method according to claim 5, when the rotation speed of the second suction device is switched from the parallel connection state to the series connection state when the first condition is satisfied. Since the power consumption of the second suction device can be reliably reduced as compared with the parallel connection state, the total power consumption of both suction devices can be reliably reduced. .

  Furthermore, according to the suction system according to claim 3 and the suction method according to claim 6, when the rotation speed of the first suction device is switched from the parallel connection state to the series connection state when the second condition is satisfied. In addition to the increase in vacuum pressure due to switching to the serial connection state by increasing the number of revolutions in the above, the suction capacity of the first suction device is increased in the series connection state by an amount that is higher than that in the parallel connection state. The vacuum pressure can be reliably increased to a higher vacuum pressure.

  In the present specification, “pressure lower than atmospheric pressure (negative pressure)” is referred to as “vacuum pressure”, and “pressure above atmospheric pressure (positive pressure)” is simply referred to as “pressure”. In addition, a state in which the vacuum pressure is close to absolute vacuum is referred to as “high vacuum pressure (high vacuum state)”, and a state in which the vacuum pressure is close to atmospheric pressure is referred to as “low vacuum pressure (low vacuum). State) ”, changing from a vacuum pressure close to atmospheric pressure to a vacuum pressure close to absolute vacuum is called“ vacuum pressure rises ”, and changes from a vacuum pressure close to absolute vacuum to a vacuum pressure close to atmospheric pressure. This is called "vacuum pressure decreases".

It is a lineblock diagram showing the composition of suction system 1 concerning an embodiment of the invention. It is explanatory drawing for demonstrating the relationship between the rotation speed (frequency of supply electric power) of the vacuum pumps 2a and 2b, the reachable vacuum pressure, and power consumption.

  Hereinafter, embodiments of a suction system and a suction method will be described with reference to the accompanying drawings.

  First, the configuration of the suction system 1 will be described with reference to the attached drawings.

  A suction system 1 shown in FIG. 1 is an example of a “suction system”, and includes vacuum pumps 2a and 2b, an inverter circuit 2c, a pressure sensor 3, and a control unit 4, and includes an injection molding machine, a suction holding device, and a vacuum packaging machine. In addition, air (an example of “gas”) is sucked by vacuum pumps 2a and 2b from various suction targets (not shown) such as a tool for degassing air in various containers such as a box and a bag (suction). The vacuum pressure can be supplied to the object). Specifically, in the suction system 1, the suction port of the vacuum pump 2a is connected to the suction target via the pipes P1a and P1, and the suction port of the vacuum pump 2b is connected to the suction target via the pipes P1b and P1. The discharge port of the vacuum pump 2a is connected to the atmosphere via the pipe P2a, and the discharge port of the vacuum pump 2b is opened to the atmosphere via the pipe P2b.

  In this case, a check valve (a ball type, a disk type, and a swing type) that allows the passage of air in the direction from the piping P1 side toward the vacuum pump 2a and restricts the passage of air in the reverse direction is provided in the piping P1a. Mechanical one-way valve such as a type: As an example, a ball check valve (CV1) is provided. The pipe P1b has a check valve (for example, a ball check valve) CV2 that allows air to pass from the pipe P1 to the vacuum pump 2b and restricts air from going in the reverse direction. It is arranged. Thereby, in this suction system 1, even when the vacuum pumps 2a and 2b are stopped, it is possible to prevent the vacuum pressure in the pipe P1 from decreasing for a certain period of time. Further, a check valve (for example, a ball check valve) CV3 that allows air to be discharged from the vacuum pump 2a and restricts the passage of air in the reverse direction (intrusion of the atmosphere) is disposed in the pipe P2a. Has been.

  In the suction system 1, one end is connected to the discharge port of the vacuum pump 2a via the pipe P2a, and the other end is connected to the suction port of the vacuum pump 2b via the pipe P1b. P3 is provided. In this case, the pipe P3 is provided with an electromagnetic valve SV that opens or closes the pipe P3 according to the control of the control unit 4 as described later. Thereby, in this suction system 1, as will be described later, a state in which the vacuum pumps 2a and 2b are connected in parallel to the suction target (parallel connection state) by closing the solenoid valve SV, and a solenoid valve By setting SV in an open state, it is possible to switch to either a state in which the vacuum pumps 2a and 2b are connected in series with respect to the suction target (series connection state).

  The vacuum pumps 2a and 2b are “inverter-controlled vacuum pumps” which are examples of “variable rotation speed suction devices”, and rotate according to the frequency of power supplied from the inverter circuit 2c as described later. A motor that rotates at a number (rotational speed) is provided as a power source. In this case, in this example, as an example, the vacuum pump 2a corresponds to a “first suction device”, and the vacuum pump 2b corresponds to a “second suction device”. Further, in the suction system 1 of this example, as an example, both motors having a rated frequency of operating power of 60 Hz as a power source and having the same suction capability per rotation speed (vacuum pumps having the same processing capability) are used. Vacuum pumps 2a and 2b are configured.

  The inverter circuit 2c constitutes a “control unit” in combination with the control unit 4, and changes the frequency of the power supplied to the vacuum pumps 2a and 2b according to the control of the control unit 4, thereby enabling the vacuum pumps 2a and 2b. Operate at an arbitrary rotational speed (controls the rotational speeds of the vacuum pumps 2a and 2b). For example, the pressure sensor 3 is disposed in the pipe P1 described above, and outputs a sensor signal that can specify the vacuum pressure in the pipe P1 when air is sucked by the vacuum pumps 2a and 2b.

  The control unit 4 controls the suction system 1 as a whole. Specifically, the control unit 4 calculates the vacuum pressure in the pipe P <b> 1 based on the sensor signal from the pressure sensor 3. Further, the control unit 4 controls the solenoid valve SV to a closed state according to the calculated vacuum pressure in the pipe P1 and the operation state of the suction system 1, and sets the vacuum pumps 2a and 2b in a parallel connection state, The vacuum pump 2a, 2b is connected in series by controlling the valve SV to an open state, and the inverter circuit 2c is controlled to supply electric power of an arbitrary frequency to the vacuum pumps 2a, 2b. The rotational speed of 2a, 2b is controlled. The relationship between the vacuum pressure in the pipe P1 and the operating state of the suction system 1, the open / close control of the solenoid valve SV, and the frequency of power supplied from the inverter circuit 2c to the vacuum pumps 2a and 2b will be described in detail later. explain.

  Next, an air suction method (vacuum pressure supply method) from the suction target by the suction system 1 will be described with reference to the accompanying drawings.

  In this suction system 1, when a start switch of an operation unit (not shown) is operated, the control unit 4 first controls the electromagnetic valve SV to a closed state and also controls the inverter circuit 2c to both vacuum pumps 2a. , 2b is started. At this time, as an example, the inverter circuit 2c operates both the vacuum pumps 2a and 2b with electric power of 60 Hz (the rated frequency of the motor mounted on both the vacuum pumps 2a and 2b). In response to this, the vacuum pump 2a sucks air in the pipe P1a, and the vacuum pump 2b sucks air in the pipe P1b.

  In this case, before the operation of the vacuum pumps 2a and 2b is started, the inside of each pipe P1, P1a, P1b, P2a, P2b, and P3 is at atmospheric pressure. Therefore, the check valve CV1 is opened when the vacuum pump 2a sucks air in the pipe P1a, and the check valve CV2 is opened when the vacuum pump 2b sucks air in the pipe P1b. From the suction target connected via the pipe P1, air is sucked toward the vacuum pump 2a via the pipe P1 and the pipe P1a, and air is directed toward the vacuum pump 2b via the pipe P1 and the pipe P1b. Is sucked. Thereby, the inside of the pipes P1, P1a, P1b is in a vacuum state, and the vacuum pressure gradually increases according to the elapsed time from the start of operation of the vacuum pumps 2a, 2b.

  Further, the air sucked from the pipe P1a to the suction port of the vacuum pump 2a is discharged from the discharge port to the pipe P2a. At this time, since the end of the pipe P2a opposite to the vacuum pump 2a is opened to the atmosphere and is at atmospheric pressure, the vacuum in the check valve CV3 is caused by the discharge pressure of air from the discharge port of the vacuum pump 2a. As a result of the pressure on the pump 2a side increasing, the check valve CV3 is opened. Thereby, the air discharged from the vacuum pump 2a to the pipe P2a passes through the check valve CV3 and is released into the atmosphere. Further, the air sucked into the suction port of the vacuum pump 2b from the pipe P1b is released from the discharge port into the atmosphere through the pipe P2b. In this case, in this example, both vacuum pumps 2a and 2b are operated with electric power of 60 Hz which is a rated frequency in a parallel connection state immediately after the start of operation. Therefore, since both vacuum pumps 2a and 2b are operated at a rotational speed at which the highest suction ability is exhibited among rotational speeds that do not cause abnormal heat generation or a significant decrease in service life, the pipes P1, P1a, It is possible to suitably increase the vacuum pressure in P1b in a short time.

  On the other hand, the control unit 4 performs the closing control of the electromagnetic valve SV and the power supply control from the inverter circuit 2c, and at the same time, calculates the vacuum pressure in the pipe P1 based on the sensor signal output from the pressure sensor 3. To start. In addition, the control unit 4 is configured such that the calculated vacuum pressure is, for example, 93.0 kPa (the amount of air sucked per unit time (per unit time when switching to the series connection state rather than continuing the operation in the parallel connection state). The amount of increase in the vacuum pressure) reaches a vacuum pressure that increases, that is, the vacuum pressure that can reduce the amount of power required to increase the target vacuum pressure by switching from the parallel connection state to the series connection state. In this case, while maintaining the rotation speed of both vacuum pumps 2a and 2b, the solenoid valve SV is controlled to switch both vacuum pumps 2a and 2b from the parallel connection state to the serial connection state ("from the parallel connection state to the serial connection" An example in which “the number of rotations of the vacuum pumps 2a and 2b at the time of switching to the state” is “the number of rotations when operating at a rated frequency of 60 Hz power”). At this time, by opening the solenoid valve SV, the pipe P2a connected to the discharge port of the vacuum pump 2a and the pipe P1b connected to the suction port of the vacuum pump 2b are connected via the pipe P3. As a result, the discharge port of the vacuum pump 2a and the suction port of the vacuum pump 2b are connected to each other.

  In addition, the air discharged from the vacuum pump 2a to the pipe P2a is sucked by the vacuum pump 2b through the pipes P3 and P1b, so that the portion on the vacuum pump 2a side of the check valve CV3 in the pipe P2a is in a vacuum state. As a result, the check valve CV3 is closed and the entry of air into the pipe P2a is restricted. Further, the vacuum pressure on the side of the vacuum pump 2b in the pipe P1b (the side connected to the pipe P3) in the pipe P1b is equivalent to the amount of air discharged from the vacuum pump 2a flowing into the pipe P1b via the pipes P2a and P3. As a result of lowering than the vacuum pressure on the P1 side, the check valve CV2 is closed and the inflow of air from the pipe P1 to the pipe P1b is restricted. Thereby, both vacuum pumps 2a and 2b will be in a serial connection state.

  In this case, in the suction system 1 of this example, when the control unit 4 switches from the parallel connection state to the series connection state, the vacuum pumps 2a and 2b are maintained in a state where they are operated with 60 Hz power. At this time, in the suction system 1, since the air discharged from the vacuum pump 2a is sucked by the vacuum pump 2b in a state where the vacuum pumps 2a and 2b are switched to the serial connection state, the exhaust resistance of the vacuum pump 2a is reduced. The suction efficiency of the vacuum pump 2a is improved by the amount reduced. Therefore, by continuing the suction of air by the vacuum pumps 2a and 2b in the state of switching from the parallel connection state to the series connection state, the vacuum pressure in the pipes P1a and P1 can be reached in the parallel connection state ( As an example, air can be sucked from the suction target even in a state where the pressure is higher than 96.8 kPa). For this reason, although both vacuum pumps 2a and 2b are rotated at the same rotational speed as in the parallel connection state, air can be continuously sucked from the suction target. Thereby, the vacuum pressure in the pipes P1a and P1 further increases.

On the other hand, by continuing the operation in the series connection state, the vacuum pressure in the pipe P1 based on the sensor signal output from the pressure sensor 3 is, for example, 99.7 kPa ( an example of “first vacuum pressure”) . when it is (an example of when filled is "first condition"), the control unit 4 controls the inverter circuit 2c, continue operation at power while maintaining (60 Hz rotation speed of the vacuum pump 2a The vacuum pump 2b is operated at a power of 40 Hz, so that the rotation speed of the vacuum pump 2b is switched from a parallel connection state to a series connection state (in this example, when operating at a power of 60 Hz). Lower than the number of revolutions). At this time, although the vacuum pressure in the pipe P1 is slightly lower than when both the vacuum pumps 2a and 2b are operated with electric power of 60 Hz, the serial connection state is maintained and the vacuum pump 2a is maintained. Since the operation at 60 Hz is continued, a sufficient amount of air can be sucked from the suction target. Thereby, the vacuum pressure sufficiently higher than the vacuum pressure (as an example, 96.8 kPa) at which the vacuum pressure in the pipe P1 can be reached in the parallel connection state (vacuum pressure required for the suction target: as an example, 99.6 kPa).

In this case, for example, when the state of the suction target changes and a large amount of air is sucked from the suction target per unit time (a state in which the load on the suction system 1 is increased), suction is performed in the above operating state. It may be difficult to sufficiently suck air from the target, and the vacuum pressure in the pipe P1 may gradually decrease. Therefore, as an example, the control unit 4 is configured such that the vacuum pressure in the pipe P1 based on the sensor signal output from the pressure sensor 3 is 98.0 kPa (“ ( An example when the “ second condition” is satisfied), the inverter circuit 2c is controlled to maintain the rotation speed of the vacuum pump 2b (an electric power of 40 Hz). The rotation speed at the time when the rotation speed of the vacuum pump 2a is switched from the parallel connection state to the series connection state by operating the vacuum pump 2a with the power of 80 Hz (in this example, the power of 60 Hz) Rotation speed when driving with

  As a result, a sufficient amount of air can be sucked from the suction target as much as the amount of suction by the vacuum pump 2a increases, and the vacuum pressure in the pipes P1a and P1 gradually increases. In this operation state, the motor of the vacuum pump 2a is supplied with electric power having a frequency higher than the rated frequency of 60 Hz and the rotational speed is increased, but the air discharged from the vacuum pump 2a is Since the burden on the vacuum pump 2a is reduced by the amount sucked by 2b, a situation in which abnormal heat generation or a decrease in the service life of the vacuum pump 2a occurs is avoided.

  In this case, in this suction system 1, as shown in FIG. 2, when the vacuum pumps 2a and 2b connected in parallel are operated at a power of 60 Hz, the vacuum pressure in the pipe P1 is 96.8 kPa at the maximum. Confirmed to reach. Moreover, the power consumption by the vacuum pumps 2a and 2b when the vacuum pressure reached 96.8 kPa was 8.2 kW. On the other hand, when the vacuum pumps 2a and 2b are switched to the serial connection state while maintaining the rotation speed, that is, when the vacuum pumps 2a and 2b in the serial connection state are operated with 60 Hz electric power, the vacuum in the pipe P1 It was confirmed that the pressure reached a maximum of 99.9 kPa. Moreover, the power consumption by the vacuum pumps 2a and 2b when the vacuum pressure reached 99.9 kPa was 5.6 kW.

  In contrast, when the vacuum pump 2a is operated with 60 Hz power and the vacuum pump 2b is operated with 40 Hz power in the serial connection state (the rotation speed of the vacuum pump 2b is changed from the parallel connection state to the serial connection state). It was confirmed that the vacuum pressure in the pipe P1 reached 99.6 kPa at the maximum when the rotational speed was decreased from the rotational speed at the time of switching to. Moreover, the power consumption by the vacuum pumps 2a and 2b when the vacuum pressure reached 99.6 kPa was 4.4 kW. Therefore, when the rotational speed of the vacuum pump 2b is reduced in the series connection state, the reachable vacuum pressure is slightly lower than when both vacuum pumps 2a and 2b are operated with 60 Hz power in the series connection state. It can be seen that the power consumption can be sufficiently reduced while allowing a sufficient amount of air to be sucked so that the vacuum pressure is sufficiently higher than when operating in a parallel connection state.

  On the other hand, although different from the above example, in a serial connection state, when 80 Hz power is supplied to the vacuum pump 2a and 60 Hz power is supplied to the vacuum pump 2b (the rotation speed of the vacuum pump 2b). When the rotational speed of the vacuum pump 2a is increased above the rotational speed at the time of switching from the parallel connection state to the serial connection state), the vacuum pressure in the pipe P1 is 100.1 kPa at the maximum. It was confirmed that However, the power consumption by the vacuum pumps 2a and 2b when the vacuum pressure reaches 100.1 kPa is 5.8 kW, and it has been confirmed that the running cost increases when such an operation state is continued.

  On the other hand, when the vacuum pump 2a is operated with 80 Hz power and the vacuum pump 2b is operated with 40 Hz power in the serial connection state as in the above example (the rotational speed of the vacuum pump 2b is decreased). And when the number of rotations of the vacuum pump 2a is increased), it was confirmed that the vacuum pressure in the pipe P1 reached 99.9 kPa at the maximum. Further, the power consumption by the vacuum pumps 2a and 2b when the vacuum pressure reached 99.9 kPa was 4.8 kW. Therefore, the rotational speed at the time when the rotational speed of the vacuum pump 2b is lowered from the rotational speed at the time of switching from the parallel connection state to the serial connection state and the rotational speed of the vacuum pump 2a is switched from the parallel connection state to the serial connection state. However, the reachable vacuum pressure is slightly lower than when the rotational speed of the vacuum pump 2a is simply increased by switching from the parallel connection state to the series connection state, but both vacuum pumps 2a, 2b in the serial connection state. When sucking a sufficient amount of air so that the vacuum pressure is about the same as when the number of rotations is not changed (when both vacuum pumps 2a and 2b are operated with 60 Hz power), the power consumption is sufficiently high It can be seen that it can be reduced.

As described above, according to the suction system 1 and the suction method by the suction system 1, when the “first condition” is satisfied in the serial connection state, the rotation speed of the vacuum pump 2b is reduced, and the vacuum pump 2b by increasing the rotational speed of the vacuum pump 2a when the "second condition" is satisfied in a state in which reduced rotation speed, a higher vacuum pressure than the parallel connection state by switching to series connection state As described above, a sufficient amount of air can be sucked from the suction target, and the total power consumption of the vacuum pumps 2a and 2b in the serial connection state is sufficiently reduced by the amount that the rotation speed of the vacuum pump 2b is reduced. In addition, when the rotational speed of the vacuum pump 2a is increased to suck more air from the suction target in the serial connection state, the vacuum pump 2b By the amount that reduces the rotational speed, both the vacuum pump 2a, the sum of the power consumption of 2b can be avoided excessively larger situation. Thereby, the running cost can be sufficiently reduced while allowing a sufficient amount of air to be sucked from the suction target so that a sufficiently high vacuum pressure is obtained in the series connection state. Further, different from adopting a small pump or reducing the rotational speed of both vacuum pumps 2a, 2b in the parallel connection state, that is, immediately after the start of operation, that is, of both vacuum pumps 2a, 2b in the parallel connection state. By setting the number of rotations to a sufficiently high number as necessary, the vacuum pressure in the pipe can be increased in a short time.

  Further, according to the suction system 1 and the suction method by the suction system 1, the rotation at the time when the rotation speed of the vacuum pump 2b is switched from the parallel connection state to the series connection state when the “first condition” is satisfied. By lowering the number than the number, the power consumption of the vacuum pump 2b can be surely reduced as compared with the parallel connection state, so that the sum of the power consumption of both the vacuum pumps 2a and 2b can be surely reduced. .

  Further, according to the suction system 1 and the suction method by the suction system 1, the rotation at the time when the rotation speed of the vacuum pump 2a is switched from the parallel connection state to the series connection state when the “second condition” is satisfied. In addition to the increase in vacuum pressure due to switching to the serial connection state, the vacuum pressure in the series connection state is increased by the amount that the suction capacity of the vacuum pump 2a is higher than that in the parallel connection state. It can be reliably increased to a higher vacuum pressure.

The configuration of the “suction system” and the specific content of the “suction method” are not limited to the configuration of the suction system 1 and the example of the method of sucking air from the suction target by the suction system 1 .

For example , in a parallel connection state, a configuration and a method for operating both vacuum pumps 2a and 2b by supplying electric power of 60 Hz, which is the rated frequency of the motor, respectively (the rotation speed of both vacuum pumps 2a and 2b in the parallel connection state, The configuration / method for maintaining the operation at the power of the rated frequency has been described. Instead of such a configuration / method, the vacuum pumps 2a and 2b are connected to the vacuum pumps 2a and 2b in a parallel connection state rather than the rated frequency of the motor. It is also possible to employ a configuration / method in which each of the vacuum pumps 2a and 2b is arbitrarily changed in operation in a parallel connection state by supplying low frequency power.

  In addition, when switching from the parallel connection state to the serial connection state, the configuration and method of operating both vacuum pumps 2a and 2b with 60 Hz power while maintaining the rotation speed at the time of switching have been described as an example. Instead of such a configuration / method, when switching from the parallel connection state to the series connection state, the configuration / method for operating both vacuum pumps 2a, 2b at a higher rotational speed than the rotational speed at the time of switching, or the parallel connection state It is also possible to employ a configuration / method in which both vacuum pumps 2a and 2b are operated at a rotational speed lower than the rotational speed at the time of switching when switching from a serial connection state to a serial connection state.

  Further, a configuration and method for controlling the rotation speed of the vacuum pumps 2a and 2b by adopting the vacuum pumps 2a and 2b using an inverter control type motor as a power source and changing the frequency of the electric power supplied from the inverter circuit 2c. As explained in the example, for example, a variable voltage control type “vacuum pump” that uses a motor whose rotational speed changes according to the voltage of the supplied power as a power source is adopted, and the power supplied to the “vacuum pump” It is also possible to adopt a configuration / method for controlling the number of revolutions by changing the voltage.

DESCRIPTION OF SYMBOLS 1 Suction system 2a, 2b Vacuum pump 2c Inverter circuit 3 Pressure sensor 4 Control part CV1-CV3 Check valve P1, P1a, P1b, P2a, P2b, P3 Piping SV Solenoid valve

Claims (6)

A parallel connection state in which the first suction device and the second suction device are provided so that gas can be sucked from the suction target by the suction devices, and the suction ports of the suction devices are connected to the suction target, respectively. The suction port of the first suction device is connected to the suction target and can be switched to either a serial connection state in which the suction port of the second suction device is connected to the discharge port of the first suction device. A suction system,
A rotation speed variable type suction device as both the suction devices;
A control unit for controlling the rotational speed of both suction devices,
The controller includes a first vacuum pressure in which a vacuum pressure in a pipe connecting the suction system to the suction target is defined in advance in a state where the suction devices are switched from the parallel connection state to the series connection state. When the first condition of increasing to the second condition is satisfied, the rotational speed of the second suction device is decreased, and the vacuum pressure in the pipe is reduced when the rotational speed of the second suction device is decreased. The suction system which raises the rotation speed of the said 1st suction device, when the 2nd condition that it falls to the 2nd vacuum pressure prescribed | regulated lower than 1 vacuum pressure is satisfy | filled.   2. The control unit according to claim 1, wherein when the first condition is satisfied, the control unit reduces the rotation speed of the second suction device to be lower than the rotation speed at the time of switching from the parallel connection state to the series connection state. Suction system.   The said control part raises the rotation speed of a said 1st attraction | suction apparatus rather than the rotation speed in the time of switching from the said parallel connection state to the said series connection state, when the said 2nd condition is satisfy | filled. The suction system described. The first suction device of variable rotation speed type and the second suction device of variable rotation speed type are provided so that gas can be sucked from the suction target by the two suction devices, and the suction ports of the two suction devices are suctioned. A parallel connection state that connects to each target, and a serial connection that connects the suction port of the first suction device to the suction target and connects the suction port of the second suction device to the discharge port of the first suction device A suction method for sucking the gas from the suction target by a suction system configured to be switchable to any of the states,
In a state where both the suction devices are switched from the parallel connection state to the series connection state, the vacuum pressure in the pipe connecting the suction system to the suction target rises to a first vacuum pressure defined in advance. When one condition is satisfied, the rotational speed of the second suction device is reduced, and the vacuum pressure in the pipe is lower than the first vacuum pressure in a state where the rotational speed of the second suction device is reduced. lower predefined suction method increases the rotational speed of the first suction device when the second condition to decrease until the second vacuum pressure is met.   The suction method according to claim 4, wherein when the first condition is satisfied, the rotational speed of the second suction device is made lower than the rotational speed at the time of switching from the parallel connection state to the series connection state.   6. The suction method according to claim 4, wherein when the second condition is satisfied, the rotational speed of the first suction device is increased from the rotational speed at the time of switching from the parallel connection state to the series connection state.

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