JP6954642B2 - Exhaust system and exhaust system control method - Google Patents

Description

The present invention relates to an exhaust system configured to include a plurality of exhaust devices connected to an exhaust target via a connecting pipe, and an exhaust device control method for controlling each exhaust device in such an exhaust system. ..

As an exhaust system and an exhaust device control method of this kind, the applicant has described an exhaust system in which air is sucked and exhausted by a vacuum pump from an exhaust object such as an injection molding machine or a suction holding device, and a control method thereof in the following patent documents. It is disclosed in. The exhaust system disclosed by the applicant is equipped with a plurality of vacuum pumps (vacuum pumps with variable exhaust capacity) powered by a motor (motor) operated by the power supplied from the inverter circuit, and these vacuums. The pump is connected in parallel to the exhaust target via the connecting pipe.

In this exhaust system, the control unit identifies the vacuum pressure in the connection pipe based on the sensor signal from the pressure sensor arranged in the connection pipe, and the specified vacuum pressure allows the specified vacuum pressure with respect to the target vacuum pressure. Control to control each inverter circuit so that the vacuum pressure is within the range and change the state of power supply to each vacuum pump (that is, the number of vacuum pumps to be operated and the number of rotations of the vacuum pumps in operation). conduct. As a result, in this exhaust system, the number of vacuum pumps required to keep the vacuum pressure in the connection pipe within the permissible range with respect to the target vacuum pressure is operated at the required rotation speed, and the appropriate amount from the exhaust target. Air is continuously evacuated.

Japanese Unexamined Patent Publication No. 2015-203348 (pages 12-28, Fig. 1-6)

However, the exhaust system disclosed by the applicant and its control method have the following problems to be improved. Specifically, in the exhaust system and control method disclosed by the applicant, the control unit operates the vacuum pump so that the vacuum pressure in the connecting pipe is within the allowable range with respect to the target vacuum pressure. A configuration and control method for controlling the operating state of each vacuum pump by specifying the number of units and the number of rotations of the vacuum pumps in operation (for example, the rotation number of the motor mounted on the vacuum pump as a power source) are adopted. ing.

As a result, in the exhaust system and control method disclosed by the applicant, when the load increases (when it is necessary to exhaust a large amount of air from the exhaust target), the control unit operates the number of vacuum pumps. By increasing or increasing the number of revolutions of the vacuum pump in operation, it is possible to maintain the vacuum pressure in the connecting pipe at a pressure within an allowable range with respect to the target vacuum pressure. Further, in the exhaust system and control method disclosed by the applicant, when the load is reduced (when the amount of air to be exhausted from the exhaust target is reduced), the control unit reduces the number of vacuum pumps to be operated. It is possible to maintain the vacuum pressure in the connecting pipe at a pressure within the permissible range with respect to the target vacuum pressure by making the vacuum pump rotate or reducing the rotation speed of the vacuum pump during operation.

In this case, when the load is reduced as described above, when the vacuum pressure in the connecting pipe is increased by the exhaust by the vacuum pump during continuous operation, the rotation speed of those vacuum pumps is decreased to be a unit from the exhaust target. A process is performed to reduce the vacuum pressure in the connection pipe by reducing the amount of air exhausted per hour, and the vacuum pressure in the connection pipe is the target vacuum pressure even when the number of revolutions is reduced to a predetermined value. When it is higher than the permissible range for (when the amount of air discharged from the exhaust target per unit time is too large), a process of reducing the number of operating vacuum pumps is performed. As a result, the power consumption is reduced by the amount of stopping the vacuum pump that is unnecessary for maintaining the vacuum pressure in the connecting pipe at a pressure within the allowable range with respect to the target vacuum pressure.

On the other hand, in the vacuum pump adopted in this type of exhaust system, as shown in FIG. 4, the reachable vacuum pressure (hereinafter, also referred to as “reachable vacuum pressure”) changes according to the number of revolutions. In the figure, the upper limit rotation speed of the allowable range is 100.0%, the lower limit rotation speed of the allowable range is 33.3%, and five types of rotation including the upper limit rotation speed and the lower limit rotation speed. Taking a number as an example, the relationship between the displacement from the exhaust target (volume of air exhausted from the vacuum pump at 1 atm) and the vacuum pressure in the connection pipe is illustrated for each rotation speed. There is. That is, in the example vacuum pump shown in the figure, the vacuum pressure a at which the displacement is minimized when operated at a rotation speed of 100.0% is the reachable vacuum pressure at a rotation speed of 100.0%. The vacuum pressure e that minimizes the displacement when operated at a rotation speed of 33.3% is the reachable vacuum pressure at a rotation speed of 33.3%.

In this case, in the control method in the exhaust system disclosed by the applicant, as an example, when the vacuum pressure in the connecting pipe is higher than the allowable range for the target vacuum pressure in the state where three vacuum pumps are operating. When the vacuum pressure in the connection pipe is higher than the allowable range for the target vacuum pressure even if the rotation speed of each vacuum pump is gradually reduced to 66.7%, three vacuum pumps are used. A configuration is adopted in which two of the vacuum pumps are continuously operated and the remaining one is stopped.

Therefore, the three vacuum pumps are operated with the target vacuum pressure set to a pressure lower than the vacuum pressure c, which is the reachable vacuum pressure when each vacuum pump is operated at a rotation speed of 66.7%. When the load decreases while the load is on, the vacuum pressure in the connection pipe becomes higher than the target vacuum pressure when the rotation speed of each vacuum pump is 66.7% or more, so the rotation speed is 66. Even if it is reduced to 0.7%, the vacuum pressure in the connecting pipe will be higher than the allowable range for the target vacuum pressure. As a result, when the target vacuum pressure is set in this way, it is determined that the detected vacuum pressure is higher than the target vacuum pressure when the load is reduced during the operation of the three units, and 3 in order to further reduce the vacuum pressure. A process is performed to stop one of the vacuum pumps.

However, for example, in a state where the target vacuum pressure is set to the vacuum pressure b (an example of a pressure higher than the vacuum pressure c which is the reachable vacuum pressure when the vacuum pump is operated at a rotation speed of 66.7%) 3 When the load is reduced while operating the table vacuum pump, the vacuum pressure in the connection pipe is 83.3% when the rotation speed of each vacuum pump is reduced to 83.3%. Since the reachable vacuum pressure at the rotation speed of is the vacuum pressure b, which is the target vacuum pressure, the rotation speed of each vacuum pump is not further reduced, and the rotation speed of 83.3% is maintained, resulting in the result. As a result, the state in which the three vacuum pumps 2 are operating is maintained.

As described above, in the above control example, when the target vacuum pressure is set to a pressure lower than the vacuum pressure c, one of the three vacuum pumps is stopped, whereas the target vacuum pressure is set to the vacuum pressure. When the pressure is set higher than c (vacuum pressure b in the above example), the three vacuum pumps are continuously operated. In this case, for example, by setting the target vacuum pressure to the vacuum pressure b as in the above example, the three vacuum pumps are continuously operated at a rotation speed of 83.3% and the vacuum pressure b is maintained. In the state, as shown in FIG. 4, the state in which the amount of exhaust by each vacuum pump is very small, that is, the state in which each vacuum pump is substantially not functioning is maintained.

On the other hand, the vacuum pressure b set as the target vacuum pressure is the reachable vacuum pressure when the rotation speed of each vacuum pump is 83.3%, so that even if the three vacuum pumps are not operated, it is not necessary to operate the three vacuum pumps. It can be reached by operating one vacuum pump at a speed of 83.3%. Nevertheless, it is difficult to reduce the power consumption of the exhaust system because each vacuum pump, which is virtually non-functional, is continuously operated at a high rotation speed of 83.3%. .. Therefore, it is preferable to improve the power consumption in the state as in the above example so as to be reducible.

The present invention has been made in view of such problems to be improved, and an object of the present invention is to provide an exhaust system and an exhaust device control method capable of further reducing power consumption.

In order to achieve the above object, the exhaust system according to claim 1 is configured so that gas can be exhausted from the exhaust target, and N units (N is two or more) connected in parallel to the exhaust target via a connection pipe. An exhaust device (natural number), a vacuum pressure sensor that detects the vacuum pressure in the connection pipe and outputs a detection signal, and a vacuum pressure in the connection pipe specified based on the detection signal are specified in advance. An exhaust system including a control unit that controls the operation of each of the exhaust devices so that the vacuum pressure is within the pressure range, and at least one of the exhaust devices exhausts the gas according to the number of revolutions. The control unit is composed of a variable exhaust device whose exhaust capacity from a target changes, and the control unit is specified based on the detection signal in a state where a plurality of the exhaust devices including the variable exhaust device are operated. When the vacuum pressure in the connecting pipe becomes constant within the pressure range specified in advance, the exhaust is based on the number of rotations of the variable exhaust device in operation and the vacuum pressure in the connecting pipe. It is determined whether or not there is the variable exhaust device operating in the exhaust capacity reduced state in which the exhaust amount of the gas from the target is equal to or less than the predetermined exhaust amount, and the variable exhaust device is operating in the exhaust capacity reduced state. When the variable exhaust device is present, at least one variable exhaust device operating in a reduced exhaust capacity state is stopped while continuing the operation of at least one of the variable exhaust devices.

The exhaust system according to claim 2 is the exhaust system according to claim 1, wherein the control unit has a plurality of variable exhaust devices operating in the exhaust capacity reduced state, and the exhaust capacity is reduced. When the variable exhaust device having a rotation speed different from the rotation speed of other variable exhaust devices is present in each of the variable exhaust devices in operation, the variable exhaust device operating in the reduced exhaust capacity state is concerned. At least one of the variable exhaust devices other than the variable exhaust device having the highest rotation speed among the variable exhaust devices is stopped.

The exhaust device control method according to claim 3 is an exhaust device of N units (N is a natural number of 2 or more) which is configured to be able to exhaust gas from the exhaust target and is connected in parallel to the exhaust target via a connection pipe. And an exhaust system including an exhaust system including a vacuum pressure sensor that detects the vacuum pressure in the connection pipe and outputs a detection signal as a control target, and a vacuum pressure in the connection pipe specified based on the detection signal. Is an exhaust device control method for controlling the operation of each exhaust device so that the pressure is within a predetermined pressure range, and at least one of the exhaust devices exhausts the gas according to the number of revolutions. In the exhaust system composed of a variable exhaust device whose exhaust capacity from a target changes, the said exhaust system is specified based on the detection signal in a state where a plurality of the exhaust devices including the variable exhaust device are operated. When the vacuum pressure in the connection pipe becomes constant within the pressure range specified in advance, the exhaust is based on the number of rotations of the variable exhaust device in operation and the vacuum pressure in the connection pipe. It is determined whether or not there is the variable exhaust device operating in the exhaust capacity reduced state in which the exhaust amount of the gas from the target is equal to or less than the predetermined exhaust amount, and the variable exhaust device is operating in the exhaust capacity reduced state. When the variable exhaust device is present, at least one variable exhaust device operating in a reduced exhaust capacity state is stopped while continuing the operation of at least one of the variable exhaust devices.

The exhaust device control method according to claim 4 is the exhaust device control method according to claim 3, wherein a plurality of the variable exhaust devices operating in the exhaust capacity reduced state exist and operate in the exhaust capacity reduced state. When the variable exhaust device whose rotation speed is different from the rotation speed of other variable exhaust devices is present in each of the variable exhaust devices in the medium, each of the variable exhaust devices operating in the reduced exhaust capacity state. At least one of the variable exhaust devices other than the variable exhaust device having the highest rotation speed among the variable exhaust devices is stopped.

The above "when the vacuum pressure in the connection pipe becomes constant within the pressure range specified in advance" means that "the vacuum pressure in the connection pipe does not deviate from the pressure range specified in advance". It means "when maintained". Therefore, "when the vacuum pressure in the connection pipe fluctuates slightly without deviating from the pressure range specified in advance", "the vacuum pressure in the connection pipe becomes constant within the pressure range specified in advance". Included in "when".

In the exhaust system according to claim 1 and the exhaust device control method according to claim 3, in a state where a plurality of exhaust devices including a variable exhaust device are operated, in a connection pipe specified based on a detection signal. When the vacuum pressure becomes constant within the pressure range specified in advance, the amount of gas exhausted from the exhaust target is determined in advance based on the number of rotations of the variable exhaust device in operation and the vacuum pressure in the connection pipe. It is determined whether or not there is a variable exhaust device operating in a reduced exhaust capacity state where the exhaust capacity is less than the specified amount, and at least when there is a variable exhaust device operating in a reduced exhaust capacity state. While continuing the operation of one exhaust device, at least one variable exhaust device operating in a reduced exhaust capacity state is stopped.

Therefore, according to the exhaust system according to claim 1 and the exhaust device control method according to claim 3, any one of the variable exhaust devices is in a state where a plurality of exhaust devices are operating. , When the amount of air exhausted from the exhaust target is extremely small and the exhaust capacity is reduced, it is determined that only one exhaust device is operating or all of the operating exhaust devices are in the reduced exhaust capacity state. Unnecessary variable exhaust system that is not functioning substantially is stopped until it is not in the state of failure, so the power consumption of the exhaust system is the same as the power supplied to the stopped variable exhaust system. Can be reduced. As a result, the running cost of the exhaust system can be further reduced.

In the exhaust system according to claim 2 and the exhaust device control method according to claim 4, there are a plurality of variable exhaust devices operating in a reduced exhaust capacity state, and each variable type operating in a reduced exhaust capacity state. When there is a variable exhaust system whose rotation speed is different from that of other variable exhaust devices in the exhaust system, the rotation speed is higher in each variable exhaust system operating in a reduced exhaust capacity state. Stop at least one of the variable exhaust devices except the highest variable exhaust system.

Therefore, according to the exhaust system according to claim 2 and the exhaust device control method according to claim 4, in a situation where there are a plurality of variable exhaust devices operating in a reduced exhaust capacity state, the exhaust capacity is reduced. Unlike the configuration and method of stopping the variable exhaust device with the highest rotation speed among the variable exhaust devices in operation, when at least one variable exhaust device in operation is stopped in a state of reduced exhaust capacity. In addition, without increasing the rotation speed of the variable exhaust system during operation or restarting the operation of the variable exhaust system that is stopped, among each variable exhaust system that is operating in a reduced exhaust capacity state. By simply maintaining the operating state (rotation speed) of the variable exhaust system with the highest rotation speed, the vacuum pressure within the permissible range with respect to the target vacuum pressure, which is the reachable vacuum pressure of the variable exhaust system operating at that rotation speed. Can be maintained.

It is a block diagram which shows the structure of the exhaust system 1 which concerns on embodiment of this invention. It is a flowchart of the displacement adjustment process 10 executed by the control unit 6 in the exhaust system 1 which concerns on embodiment of this invention. It is explanatory drawing for demonstrating an example of the operating state of the vacuum pumps 2a to 2c at the time of execution of the displacement adjustment process 10 by the exhaust system 1 which concerns on embodiment of this invention. The relationship between the "displacement amount from the exhaust target X" and the "vacuum pressure" of the vacuum pumps 2a to 2c in the exhaust system 1 according to the embodiment of the present invention is 33.3% to 100.0%, respectively. It is a figure shown for each rotation speed.

Hereinafter, embodiments of an exhaust system and an exhaust device control method will be described with reference to the accompanying drawings.

First, the configuration of the exhaust system 1 will be described with reference to the accompanying drawings.

The exhaust system 1 shown in FIG. 1 is an example of an “exhaust system”, and similarly to the above-mentioned exhaust system disclosed by the applicant, various exhausts such as an injection molding machine, a suction holding device, and a vacuum packaging machine. It is configured so that air (an example of "gas") can be sucked from the target X and exhausted (a vacuum pressure is supplied to the exhaust target X). Specifically, the exhaust system 1 includes vacuum pumps 2a to 2c (an example of N = 3 "exhaust devices": hereinafter also referred to as "vacuum pump 2" when these are not distinguished), inverter circuits 3a to 3c (N = 3 "exhaust devices"). Hereinafter, when these are not distinguished, they are also referred to as "inverter circuit 3"), a connection pipe 4, a vacuum pressure sensor 5, a control unit 6, and a storage unit 7.

The vacuum pump 2 is an "inverter-controlled vacuum pump" which is an example of "a variable exhaust device whose exhaust capacity from an exhaust target changes according to the number of revolutions", and in the exhaust system 1 of this example, each is The vacuum pump 2 is connected in parallel to the exhaust target X via the connection pipe 4 (an example of the “connection pipe”). As an example, the vacuum pump 2 is composed of a rotor type pump (rotary pump) such as a vane pump, and as will be described later, the powers P2a to P2c supplied from each inverter circuit 3 (hereinafter, when not distinguished). A motor that rotates at a rotation speed (rotation speed) corresponding to the frequency of "electric power P2" is provided as a power source, and the power output shaft of the motor and the input shaft of the pump body form a power transmission mechanism (coupling or coupling). , Belt & pulley, etc.) are connected to each other.

That is, in the vacuum pump 2 of this example, the rotation speed of the motor (the rotation speed of the power output shaft) and the rotation speed of the input shaft of the pump body (the rotation speed of the rotor) are fixed at a predetermined ratio. , The rotation speed of the rotor changes according to the increase or decrease of the rotation speed of the motor. In the following description, in order to facilitate understanding of the operation of the exhaust system 1, "the number of revolutions of the power output shaft in the motor mounted on the vacuum pump 2" is simply referred to as "the number of revolutions of the vacuum pump 2". say. In this case, the exhaust system 1 of this example includes, for example, motors having a rated frequency of operating power of 60 Hz, and vacuum pumps having the same exhaust capacity per rotation speed (vacuum pumps having the same exhaust capacity). The vacuum pump 2 is configured.

A "variable exhaust device" such as the vacuum pump 2 is in a state in which it is difficult to sufficiently exhaust air (suck air) in an operating state below a predetermined rotation speed. Therefore, in this example, as an example, when the rotation speed when the power P2 of the above rated frequency (60 Hz) is supplied to each vacuum pump 2 is set to the upper limit of 100.0%, the rotation speed is 33. A rotation speed of 3.3% is specified as a lower limit, and each vacuum pump 2 is specified to operate at a rotation speed between 33.3% and 100.0%. In each vacuum pump 2 adopted in the exhaust system 1 of this example, the relationship between the "displacement amount from the exhaust target X" and the "vacuum pressure" for each rotation speed is as shown in FIG. It has an exhaust capacity that makes it.

The inverter circuit 3 and the control unit 6 form a "control unit". In this case, in the exhaust system 1 of this example, the inverter circuit 3a changes the frequency of the power P2a supplied to the vacuum pump 2a according to the control signal S3a from the control unit 6, and the inverter circuit 3b changes the frequency of the control signal S3b from the control unit 6. The frequency of the power P2b supplied to the vacuum pump 2b is changed according to the above, and the frequency of the power P2c supplied to the vacuum pump 2c by the inverter circuit 3c according to the control signal S3c from the control unit 6 is changed. A configuration is adopted in which the operation is performed at an arbitrary rotation speed between 33.3% and 100.0% of the above (controlling the rotation speed of each vacuum pump 2).

In this example in which each vacuum pump 2 is operated with the rotation speed when the power P2 of 60 Hz, which is the rated frequency, is supplied from the inverter circuit 3 as 100.0%, the vacuum supplied with the power P2 of 50 Hz. The pump 2 operates at 83.3% rotation speed, the vacuum pump 2 that supplies 40 Hz power P2 operates at 66.7% rotation speed, and the vacuum pump 2 that supplies 30 Hz power P2 50.0. In addition to operating at a rotation speed of%, the vacuum pump 2 supplied with the power P2 of 20 Hz operates at a rotation speed of 33.3%.

The connection pipe 4 is a pressure pipe that connects each vacuum pump 2 in parallel to the exhaust target X. In the exhaust system 1 of this example, the vacuum pressure sensor 5 is attached to the connection pipe 4. There is. Instead of the configuration of the exhaust system 1 provided with the connection pipe 4 as a component of the exhaust system 1, each vacuum pump 2 is connected to the existing pressure pipe connected to the exhaust target X to connect the vacuum pressure sensor 5. It is also possible to adopt a configuration in which the components are arranged (a configuration using a “connection pipe” that is not a component of the “exhaust system”). The vacuum pressure sensor (vacuum degree sensor) 5 is an example of a "vacuum pressure sensor", and is arranged in the connection pipe 4 as described above to detect the vacuum pressure (vacuum degree) in the connection pipe 4. , Outputs a sensor signal S5 (an example of a "detection signal") corresponding to the detected vacuum pressure.

As described above, the control unit 6 constitutes a "control unit" in combination with each inverter circuit 3, and controls the exhaust system 1 in a comprehensive manner. As will be described later, the control unit 6 executes the exhaust volume adjusting process 10 shown in FIG. 2 to control signals S3a to S3c (hereinafter, also referred to as “control signal S3” when not distinguished) for each inverter circuit 3. ) Is output so that the vacuum pressure in the connection pipe 4 is within the permissible range for the preset target vacuum pressure (for example, within ± 5.0% of the set target vacuum pressure). Each vacuum pump 2 is operated so as to be.

Specifically, the control unit 6 identifies the vacuum pressure in the connection pipe 4 based on the sensor signal S5 output from the vacuum pressure sensor 5, and sets the preset target vacuum pressure and the sensor signal S5. Based on the vacuum pressure specified based on the above, how to operate each vacuum pump 2 is specified (determined). At this time, the control unit 6 determines that the load has decreased when the vacuum pressure rises to a vacuum pressure higher than the allowable range for the target vacuum pressure (an example of the "predetermined pressure range"), and allows the target vacuum pressure. It is determined that the load has increased when the vacuum pressure drops below the range.

Further, when the load is reduced, the control unit 6 outputs a control signal S3 to each of the inverter circuits 3 to change the operating state of each vacuum pump 2 to reduce the displacement of air in the exhaust system 1 as a whole. At the same time, when the load increases, the control signal S3 is output to each of the inverter circuits 3 to change the operating state of each vacuum pump 2 to increase the displacement of air in the exhaust system 1 as a whole, thereby connecting. The vacuum pressure in the pipe 4 is maintained at the vacuum pressure within the above vacuum pressure range. The specific contents of the displacement adjustment process 10 by the control unit 6 will be described in detail later.

The storage unit 7 stores the operation program of the control unit 6, the calculation result of the control unit 6, and the control data for the control unit 6 to control the vacuum pump 2 via each inverter circuit 3 in the displacement adjustment process 10 described later. Memorize D etc.

Next, the exhaust treatment of air from the exhaust target X (vacuum pressure supply treatment) by the exhaust system 1 will be described with reference to the attached drawings.

When exhausting air from the exhaust target X by the exhaust system 1, first, a target vacuum pressure is set by operating an operation unit (not shown). At this time, in the exhaust system 1 of this example, as an example, the rotation speed of the vacuum pump 2 supplied with the power P2 of 60 Hz is set to 100.0%, and the vacuum pump operated at the rotation speed of 100.0%. Target vacuum pressure by designating an arbitrary vacuum pressure from within the pressure range with the reachable vacuum pressure of 2 (vacuum pressure a shown in FIG. 4) as the upper limit and the vacuum pressure of 50.0% of the vacuum pressure as the lower limit. It is possible to set as. At this time, as an example, the vacuum pressure e shown in FIG. 4 is set as the target vacuum pressure.

Next, the exhaust process is started by operating the operation unit. At this time, the control unit 6 first outputs the control signal S3a to the inverter circuit 3a to supply the vacuum pump 2a with the electric power P2a of 20 Hz (the vacuum pump 2a is operated at a rotation speed of 33.3%). ), And the displacement adjustment process 10 shown in FIG. 2 is started.

In the displacement adjustment process 10, the control unit 6 first identifies the vacuum pressure in the connection pipe 4 based on the sensor signal S5 output from the vacuum pressure sensor 5 (step 11). Next, the control unit 6 determines whether or not the specified vacuum pressure is within an allowable range with respect to the target vacuum pressure (step 12). In this case, since the vacuum pressure inside the connecting pipe 4 is as low as the atmospheric pressure immediately after the start of processing, the vacuum pressure specified based on the sensor signal S5 is within the permissible range for the target vacuum pressure in the control unit 6. Is also determined to have a low vacuum pressure.

Therefore, the control unit 6 increases the rotation speed of the vacuum pump 2a by outputting the control signal S3a to the inverter circuit 3a and increasing the frequency of the power P2a supplied to the vacuum pump 2a (operation of the vacuum pump). Change of state: Step 13), the amount of exhaust from the exhaust target X by the vacuum pump 2a is increased, and the process returns to step 11. In this example immediately after the start of processing, the processing of steps 11 to 13 above is performed until the vacuum pressure specified from the vacuum pressure sensor 5 based on the sensor signal S5 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure. It is repeatedly executed and the amount of exhaust from the exhaust target X is gradually increased.

Specifically, as shown in the left side of FIG. 3 as a control example of "when the displacement is increased (when the vacuum pressure is low)", first, the rotation speed of the vacuum pump 2a gradually increases from 33.3%. When the pressure is raised to 100.0%, the operation of the vacuum pump 2b is started at a rotation speed of 33.3%. At this time, the rotation speed of the vacuum pump 2a is set to 66.7% (100.0% -33.3% rotation speed) in consideration of the displacement of the vacuum pump 2b operating at the rotation speed of 33.3%. ). As a result, it is possible to avoid a situation in which the exhaust amount of the exhaust system 1 as a whole suddenly increases.

Further, when the rotation speed of the vacuum pump 2a is gradually increased from 66.7% and then rises to 100.0% again, the rotation speed of the vacuum pump 2b operating at the rotation speed of 33.3% gradually increases. Can be raised. Further, when the rotation speed of the vacuum pump 2b rises to 100.0%, the operation of the vacuum pump 2c is started at the rotation speed of 33.3%. Also at this time, the rotation speed of the vacuum pump 2b is reduced to 66.7% in consideration of the displacement of the vacuum pump 2c operating at the rotation speed of 33.3%. As a result, it is possible to avoid a situation in which the exhaust amount of the exhaust system 1 as a whole suddenly increases.

Further, when the rotation speed of the vacuum pump 2b is gradually increased from 66.7% and then rises to 100.0% again, the rotation speed of the vacuum pump 2c operating at the rotation speed of 33.3% gradually increases. Can be raised. Further, when the rotation speed of the vacuum pump 2b rises to 100.0%, the vacuum is vacuumed until the vacuum pressure specified from the vacuum pressure sensor 5 based on the sensor signal S5 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure. The state in which the three pumps 2a to 2c are operating at a rotation speed of 100.0% is maintained.

When the volume of the exhaust system 1, the connection pipe 4, and the vacuum line in the exhaust target X is small (for example, the pipe length of the connection pipe 4 is short) and the load of the exhaust system 1 is small (for example, exhaust). Before the operation of the vacuum pump 2c is started (when the two vacuum pumps 2a and 2b are operating) or before the operation of the vacuum pump 2b is started (when the target X is not moving). In the state where only the vacuum pump 2a is operating), the vacuum pressure specified based on the sensor signal S5 becomes the vacuum pressure within the permissible range with respect to the target vacuum pressure. For ease of understanding, the vacuum pressure in the connecting pipe 4 is set with respect to the target vacuum pressure before the three vacuum pumps 2a to 2c are operated at 100.0% rotation speed as described above. It is assumed that the vacuum pressure within the permissible range has not been reached. Further, instead of the above control example, when the exhaust system 1 is started, a plurality of vacuum pumps 2 may be started to operate at the same time immediately after the start of the process, but the description of such a control example will be omitted.

Further, in this example in which the target vacuum pressure set prior to the start of processing is the vacuum pressure e, for example, when the exhaust target X is not in operation and the load is small, the vacuum pumps 2a to 2c are described as described above. The vacuum pressure in the connection pipe 4 (vacuum pressure specified based on the sensor signal S5 from the vacuum pressure sensor 5) by exhausting air from the exhaust target X at a rotation speed of 100.0% for each of the three units). Rise to the vacuum pressure e. Further, when three vacuum pumps 2 are continuously operated at a rotation speed of 100.0%, the vacuum pressure in the connection pipe 4 can be reached at a rotation speed of 100.0% of each vacuum pump 2. The vacuum pressure rises toward the vacuum pressure a, which is the vacuum pressure, and becomes higher than the vacuum pressure e, which is the target vacuum pressure. Therefore, when the three vacuum pumps 2 are continuously operated at a rotation speed of 100.0%, the vacuum pressure in the connection pipe 4 specified based on the sensor signal S5 in step 11 becomes the target vacuum pressure. The vacuum pressure is specified to be higher than the permissible range for (step 12).

At this time, the control unit 6 lowers the rotation speed of the vacuum pump 2c by outputting the control signal S3c to the inverter circuit 3c and lowering the frequency of the power P2c supplied to the vacuum pump 2c (vacuum pump). Change of the operating state of: Step 13), the amount of exhaust from the exhaust target X by the vacuum pump 2c is reduced, and the process returns to step 11. Next, the above steps 11 to 13 are repeatedly executed from the exhaust target X until the vacuum pressure specified from the vacuum pressure sensor 5 based on the sensor signal S5 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure. The exhaust volume of the is gradually reduced.

Specifically, as shown in the right side of FIG. 3 as a control example of "when the exhaust amount is reduced (when the vacuum pressure is high)", first, the rotation speed of the vacuum pump 2c gradually increases from 100.0%. When the vacuum pump 2c is lowered to 33.3%, which is the lower limit of the number of revolutions, the number of revolutions of the vacuum pump 2c is maintained at 33.3%, and the number of revolutions of the vacuum pump 2b is 100. It is gradually lowered from 0.0%. Further, when the rotation speed of the vacuum pump 2b drops to 66.7%, the vacuum pump 2c is stopped and the displacement is reduced by stopping the vacuum pump 2c which was operating at the rotation speed of 33.3%. In consideration, the rotation speed of the vacuum pump 2b is increased to 100.0%. As a result, it is possible to avoid a situation in which the exhaust amount of the exhaust system 1 as a whole suddenly drops.

Further, when the rotation speed of the vacuum pump 2b is gradually lowered from 100.0% to 33.3%, which is the lower limit of the rotation speed, the rotation speed of the vacuum pump 2b is 33.3%. While maintaining the state, the rotation speed of the vacuum pump 2a is gradually lowered from 100.0%. Further, when the rotation speed of the vacuum pump 2a drops to 66.7%, the vacuum pump 2b is stopped, and the displacement due to the stop of the vacuum pump 2b operating at the rotation speed of 33.3% is reduced. In consideration, the rotation speed of the vacuum pump 2a is increased to 100.0%. As a result, it is possible to avoid a situation in which the exhaust amount of the exhaust system 1 as a whole suddenly drops.

Further, when the rotation speed of the vacuum pump 2a is gradually lowered from 100.0% to 33.3%, which is the lower limit of the rotation speed, the connection pipe 4 specified based on the sensor signal S5. The vacuum pressure inside becomes the vacuum pressure e, which is the reachable vacuum of the vacuum pump 2a in a state of being rotated at 33.3%. Therefore, the control unit 6 determines that the vacuum pressure in the connection pipe 4 specified in step 11 is a vacuum pressure within an allowable range with respect to the set target vacuum pressure (step 12), and vacuums a plurality of units. It is determined whether or not the pump 2 is operating (step 13).

At this time, since only one of the vacuum pumps 2a is in operation, the control unit 6 returns to step 11 to specify the vacuum pressure in the connection pipe 4 based on the sensor signal S5. After that, the above steps 11 to 14 are repeatedly executed until the load becomes large and it becomes necessary to exhaust a large amount of air from the exhaust target X. As a result, one of the vacuum pumps 2a continuously performs exhaust treatment at a rotation speed of 33.3%, and the vacuum pressure in the connecting pipe 4 is within the allowable range with respect to the target vacuum pressure (in this example, the vacuum pressure is within the allowable range. The state of vacuum pressure e) is maintained.

On the other hand, unlike the above example, a vacuum pressure higher than the vacuum pressure e shown in FIG. 4 may be set as the target vacuum pressure. Specifically, as an example, it is assumed that the vacuum pressure b, which is the ultimate vacuum pressure when the vacuum pump 2 is operated at a rotation speed of 83.3%, is set as the target vacuum pressure. When the start of the exhaust process is instructed by the operation of the operation unit in such a state, the control unit 6 first gradually increases the rotation speed of the vacuum pump 2a in the same manner as in the above-mentioned control example to create a vacuum. The operation of the vacuum pump 2b is started in addition to the pump 2a to gradually increase the rotation speed, and the operation of the vacuum pump 2c is started in addition to the vacuum pumps 2a and 2b to gradually increase the rotation speed. Let me. As a result, each of the three vacuum pumps 2a to 2c is in a state of operating at a rotation speed of 100.0%.

Further, when three vacuum pumps 2 are continuously operated at a rotation speed of 100.0%, the vacuum pressure in the connection pipe 4 can be reached at a rotation speed of 100.0% of each vacuum pump 2. The vacuum pressure rises toward the vacuum pressure a, which is the vacuum pressure, and becomes higher than the vacuum pressure b, which is the target vacuum pressure. Therefore, when the three vacuum pumps 2 are continuously operated at a rotation speed of 100.0%, the vacuum pressure in the connection pipe 4 specified based on the sensor signal S5 in step 11 becomes the target vacuum pressure. The vacuum pressure is specified to be higher than the permissible range for (step 12).

At this time, in the same manner as in the above-mentioned example in which the target vacuum pressure is set to the vacuum pressure e, first, the rotation speed of the vacuum pump 2c is gradually lowered from 100.0% to 33.3%. While the state is maintained, the rotation speed of the vacuum pump 2b is gradually lowered from 100.0%, and when the rotation speed of the vacuum pump 2b drops to 66.7%, the vacuum pump 2c is stopped and the vacuum pump 2c is stopped. , The rotation speed of the vacuum pump 2b can be increased to 100.0%. Next, the rotation speed of the vacuum pump 2b is gradually lowered from 100.0% to maintain the state of 33.3%, and the rotation speed of the vacuum pump 2a is gradually lowered from 100.0%.

Further, when the rotation speed of the vacuum pump 2a drops to 83.3%, the vacuum pressure in the connecting pipe 4 specified based on the sensor signal S5 in step 11 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure. (An example of the state of "when the vacuum pressure in the connection pipe specified based on the detection signal becomes constant within the pressure range specified in advance": step 12). At this time, the operation of each vacuum pump 2 is based only on whether or not the vacuum pressure in the connecting pipe 4 is within the allowable range with respect to the target vacuum pressure as in the exhaust system disclosed by the applicant. In the configuration / method for controlling the state, the vacuum pump 2a operates at 83.3% rotation speed, and the vacuum pump 2b operates at 33.3% rotation speed (two vacuum pumps 2). Is in operation) is maintained.

On the other hand, in the exhaust system 1 of this example, as described above, after determining that the vacuum pressure in the connection pipe 4 is within the allowable range with respect to the target vacuum pressure in step 12, a plurality of control units 6 are used. It is determined that the table vacuum pumps 2 (in this example, the vacuum pumps 2a and 2b) are in operation (step 14), and the operating state of the operating vacuum pump 2 at that time is specified (step 15). At this time, the control unit 6 identifies that the vacuum pump 2a is operating at a rotation speed of 83.3% and the vacuum pump 2b is operating at a rotation speed of 33.3%. Next, the control unit 6 determines the displacement of air from the exhaust target X based on the rotation speed of each of the specified vacuum pumps 2 and the vacuum pressure in the connection pipe 4 specified in step 11. It is determined whether or not there is a vacuum pump 2 operating in the following “displacement capacity reduced state” (step 16).

In this case, as shown in FIG. 4, the ultimate vacuum degree of the vacuum pump 2b operating at 33.3% rotation speed is the ultimate vacuum degree of the vacuum pump 2a operating at 83.3% rotation speed. The vacuum degree e is lower than the target vacuum degree b. Therefore, in the vacuum pump 2b, the degree of vacuum in the connecting pipe 4 is higher than the degree of reachable vacuum when operating at a rotation speed of 33.3%, so that the degree of vacuum from the exhaust target X The displacement of is extremely small (substantially almost zero). In the exhaust system 1 of this example, as an example, an operating state in which the displacement from the exhaust target X is equal to or less than the displacement A in the figure is defined as an "exhaust capacity reduced state", and as described above, it is substantially. A configuration is adopted in which the vacuum pump 2 that does not contribute to the exhaust gas treatment is stopped.

In this case, the displacement (“displacement A” in the above example) in the “reduced exhaust capacity” state can be arbitrarily changed by operating an operation unit (not shown). Also, under what vacuum pressure and at what speed the vacuum pump 2 is operated, what is the exhaust volume of the vacuum pump 2 (what kind of speed is under the current vacuum pressure)? The control data D capable of identifying the relationship between the vacuum pump 2 and the vacuum pump 2 is stored in the storage unit 7 as to whether the amount of the vacuum pump 2 is equal to or less than the “evacuation amount A”). Therefore, the control unit 6 has the vacuum pumps 2a and 2b based on the vacuum pressure specified in step 11, the rotation speeds of the vacuum pumps 2a and 2b specified in step 15, and the control data D stored in the storage unit 7. Determines whether or not is operating in the "exhaust capacity reduced state".

Specifically, in the control unit 6, for the vacuum pump 2b operating at a rotation speed of 33.3%, the reachable vacuum pressure e is the vacuum pressure (target vacuum pressure) specified in step 11. It is determined that the vehicle is operating in an "exhaust capacity reduced state" in which the amount of vacuum from the exhaust target X is smaller than the amount of exhaust A, which is lower than the vacuum pressure (vacuum pressure within the permissible range for the vacuum pressure b). An example of a state of "when there is a variable exhaust device operating in a reduced capacity state": step 16). Further, even for the vacuum pump 2a operating at a rotation speed of 83.3%, the control unit 6 has a smaller displacement from the exhaust target X under the vacuum pressure specified in step 11, so that the displacement is smaller than the displacement A. Another example of the state of "when there is a variable exhaust device operating in the reduced exhaust capacity state": step 16).

Next, the control unit 6 that determines that both the operating vacuum pumps 2a and 2b are operating in the "exhaust capacity reduced state" (there are a plurality of variable exhaust devices operating in the "exhaust capacity reduced state"). , And when there is a variable exhaust device whose rotation speed is different from the rotation speed of other variable exhaust devices in each variable exhaust device operating in a reduced exhaust capacity state "), An example of a vacuum pump 2b operating at a rotation speed of 33.3% (“variable exhaust device excluding the variable exhaust device having the highest rotation speed among each variable exhaust device operating in a reduced exhaust capacity state”” ) Is stopped.

Specifically, the control unit 6 stops the vacuum pump 2b by outputting the control signal S3b to the inverter circuit 3b and stopping the output of the electric power P2b to the vacuum pump 2b (“at least one exhaust). An example of the process of "stopping at least one variable exhaust device operating in a reduced exhaust capacity state while continuing the operation of the device": step 17). As a result, the power consumption of the exhaust system 1 is reduced by the amount of the electric power P2b supplied to the stopped vacuum pump 2b.

In this case, although it is different from the above control example, in the above step 17, the vacuum pump 2a (“the variable exhaust device having the highest rotation speed among the variable exhaust devices operating in the reduced exhaust capacity state”” When (1 example) is stopped, the reachable vacuum pressure by the vacuum pump 2b operating at 33.3% rotation speed is higher than the allowable range of vacuum pressure with respect to the target vacuum pressure (vacuum pressure b in this example). Due to the low vacuum pressure e, the vacuum pressure in the connecting pipe 4 cannot be maintained at a vacuum pressure within an allowable range with respect to the target vacuum pressure. Although such a configuration can be adopted, in the above step 17, the operation of the vacuum pump 2a operating at 83.3% rotation speed is continued, and the vacuum operating at 33.3% rotation speed is continued. In this example in which the pump 2b is stopped, the vacuum pressure in the connecting pipe 4 is within the permissible range with respect to the target vacuum pressure by maintaining the state in which the vacuum pump 2a is operated at a rotation speed of 83.3%. The state of the vacuum pressure b, which is the vacuum pressure, is maintained.

After that, until the load increases and the state shifts to a state in which it is necessary to exhaust a large amount of air from the exhaust target X, the vacuum pump 2a is only operated at a rotation speed of 83.3%, and in step 11. It is determined that the vacuum pressure in the specified connection pipe 4 is within the allowable range with respect to the target vacuum pressure (step 12), and it is determined that only one of the vacuum pumps 2a is in operation (step 12). 14), a series of processes returning to step 11 are repeatedly executed.

It should be noted that the basic control procedure (each of steps 11 to 13) regarding the change of the rotation speed of each vacuum pump 2 and the change of the number of operating units according to the vacuum pressure in the connection pipe 4 specified based on the sensor signal S5. The processing procedure) is not limited to the example of the control procedure shown in FIG. For example, the operating state of each vacuum pump 2 can be changed by adopting the same procedure as the control procedure of each embodiment of the exhaust system and its control method disclosed by the applicant in the above-mentioned patent document.

In this case, when a control procedure is adopted in which the rotation speeds of the vacuum pumps 2 in operation are set to the same rotation speeds as in the control example disclosed by the applicant as the first embodiment in the above-mentioned patent document. When the target vacuum pressure is set to the vacuum pressure b shown in FIG. 4 as in the above example, the three vacuum pumps 2a to 2c are connected at a rotation speed of 83.3%. The vacuum pressure in the pipe 4 becomes the vacuum pressure b within the allowable range with respect to the target vacuum pressure. However, even if the vacuum pumps 2a to 2c are operated at a rotation speed of 83.3% in a state where the vacuum pressure in the connection pipe 4 is the vacuum pressure b, the exhaust amount of each of the vacuum pumps 2a to 2c is still large. It will be in a state of being far below the exhaust amount A.

At this time, it is determined that all of the vacuum pumps 2a to 2c are in the "exhaust capacity reduced state" based on the number of rotations of the vacuum pump 2 in operation and the vacuum pressure in the connection pipe 4. Another example of the state that "there are multiple variable exhaust devices operating in a reduced capacity state"). In such a state, unlike the above-mentioned example, all the rotation speeds of the vacuum pumps 2a to 2c operating in the "exhaust capacity reduced state" are the same rotation speed. Therefore, the vacuum pump 2 in which the "priority for setting the operating state" of each vacuum pump 2 is set low is stopped.

At this time, when the order of the vacuum pump 2a, the vacuum pump 2b, and the vacuum pump 2c is set as the "priority for setting the operating state", first, among the vacuum pumps 2a to 2c in the "exhaust capacity reduced state". While stopping the vacuum pump 2c of the above, the vacuum pumps 2a and 2b are continuously operated at a rotation speed of 83.3% ("Variable during operation in a state of reduced exhaust capacity while continuing the operation of at least one exhaust device". Another example of the process of "stopping at least one type exhaust device"). Next, the vacuum pump 2b among the vacuum pumps 2a and 2b that are in the "exhaust capacity reduced state" even after the vacuum pump 2c is stopped is stopped, and the vacuum pump 2a is continuously operated at a rotation speed of 83.3% ("" Another example of the process of "stopping at least one variable exhaust device operating in a reduced exhaust capacity state while continuing the operation of at least one exhaust device").

As a result, the vacuum pumps 2b and 2c are stopped from the state where the three vacuum pumps 2a to 2c are operated at the rotation speed of 83.3%, and only one of the vacuum pumps 2a is 83.3%. The state of operation at the number of rotations is maintained, and the state in which the vacuum pressure in the connecting pipe 4 is within the permissible range with respect to the target vacuum pressure is maintained. As described above, instead of the control of stopping the vacuum pump 2c and then stopping the vacuum pump 2b, any two of the vacuum pumps 2a to 2c in the "exhaust capacity reduced state" (for example, the vacuum pump). It is also possible to control to stop 2b and 2c) at the same time. Even when such control is performed, only one of the vacuum pumps 2a is in a state of operating at a rotation speed of 83.3%, and the vacuum pressure in the connecting pipe 4 is a vacuum within an allowable range with respect to the target vacuum pressure. The pressure state is maintained.

As described above, in the exhaust system 1 and the exhaust device control method, the vacuum in the connection pipe 4 specified based on the sensor signal S5 from the vacuum pressure sensor 5 in the state where a plurality of vacuum pumps 2 are operated. When the pressure becomes constant within the pressure range specified in advance, the amount of air exhausted from the exhaust target X is determined in advance based on the number of rotations of the vacuum pump 2 in operation and the vacuum pressure in the connecting pipe 4. When it is determined whether or not there is a vacuum pump 2 operating in the "exhaust capacity reduced state" which is equal to or less than the specified exhaust amount, and when the vacuum pump 2 operating in the "exhaust capacity reduced state" exists. , While continuing the operation of at least one vacuum pump 2, at least one vacuum pump 2 operating in the "exhaust capacity reduced state" is stopped.

Therefore, according to the exhaust system 1 and the exhaust device control method, one (or all) of the vacuum pumps 2 is the air from the exhaust target X while the plurality of vacuum pumps 2 are operating. When only one vacuum pump 2 is operating, or all of the operating vacuum pumps 2 are determined to be in the "exhaust capacity reduced state" when the exhaust volume is extremely small. Since the unnecessary vacuum pump 2 that is not substantially functioning is stopped until the state is not completed, the power consumption of the exhaust system 1 is increased by the amount of the power P2 supplied to the stopped vacuum pump 2. Can be reduced. As a result, the running cost of the exhaust system 1 can be further reduced.

Further, in this exhaust system 1 and the exhaust device control method, there are a plurality of vacuum pumps 2 operating in the "exhaust capacity reduced state", and among the vacuum pumps 2 operating in the "exhaust capacity reduced state". When there is a vacuum pump 2 whose rotation speed is different from that of the other vacuum pumps 2, the vacuum pump 2 having the highest rotation speed among the vacuum pumps 2 operating in the "exhaust capacity reduced state" is selected. Stop at least one of the vacuum pumps 2 to be removed.

Therefore, according to the exhaust system 1 and the exhaust device control method, each vacuum pump operating in the "exhaust capacity reduced state" under the condition that there are a plurality of vacuum pumps 2 operating in the "exhaust capacity reduced state". Unlike the configuration / method of stopping the vacuum pump 2 having the highest rotation speed among 2, when at least one of the vacuum pumps 2 operating in the "exhaust capacity reduced state" is stopped, the vacuum pump in operation The vacuum pump 2 having the highest rotation speed among the vacuum pumps 2 operating in the "exhaust capacity reduced state" without increasing the rotation speed of 2 or restarting the operation of the stopped vacuum pump 2. It is possible to maintain a vacuum pressure within an allowable range with respect to a target vacuum pressure which is a reachable vacuum pressure of the vacuum pump 2 operating at that rotation speed only by maintaining the operating state (rotation speed) of.

The configuration of the "exhaust system" and the specific contents of the "exhaust device control method" are not limited to the above configuration of the exhaust system 1 and examples of the control methods of the vacuum pumps 2a to 2c in the exhaust system 1. .. For example, the number of "exhaust devices" constituting the "exhaust system" is not limited to N = 3 as in the exhaust system 1, and N = 2 or N = 4 or more is provided. An "exhaust system" can be configured. Further, an example in which all of the N = 3 "exhaust devices" are configured by the vacuum pump 2 which is a "variable exhaust device" has been described, but at least one of the N "exhaust devices" is "variable". If it is a "type exhaust device", the other "exhaust device" can also be configured as a "fixed type exhaust device in which the exhaust capacity from the exhaust target X does not change".

Further, as an example of the "variable exhaust device", the number of rotations of each vacuum pump 2 is changed by adopting a vacuum pump 2 powered by an inverter control type motor and changing the frequency of power supplied from the inverter circuit 3. The configuration and method for controlling the above are described as an example. For example, a variable voltage control type "variable exhaust device" that uses a motor whose rotation speed changes according to the voltage of the supplied power as a power source is adopted. , Adopt a configuration / method that controls the rotation speed by changing the voltage of the power supplied to the "exhaust device", or change the current using a motor that changes the rotation speed according to the current of the supplied power. It is also possible to adopt a control type "variable exhaust device" and adopt a configuration / method of controlling the number of revolutions by changing the current of the electric power supplied to the "exhaust device".

Further, the configuration in which a vacuum pump 2 or the like equipped with a motor (electric motor) as a power source is provided as an "exhaust device" and a control method thereof have been described. It is also possible to configure an "exhaust system" by providing an "exhaust device" and control those "exhaust devices" to exhaust gas (air, etc.) from the "exhaust target".

Further, the power output shaft of the power source (motor, etc.) and the input shaft of the pump body are connected to each other via a coupling, a belt, a pulley, etc., and the number of rotations of the power source (the number of rotations of the power output shaft). ) And the number of rotations of the input shaft (the number of rotations of the rotor) are fixed at a predetermined ratio. , The input shaft of the pump body is connected to each other via a variable speed type power transmission mechanism, and the ratio of the rotation speed of the power output shaft to the rotation speed of the input shaft of the pump body (rotor rotation speed). It can also be configured with an "exhaust device" that is configured to be changeable. In addition, although an example in which the rotor type vacuum pump 2 is provided has been described, a piston & cylinder type “exhaust device” (a reciprocating type “exhaust device” may also be provided. In the & cylinder type "exhaust device", the number of rotations of the crank shaft to which the piston is connected corresponds to the "number of rotations of the exhaust device".

1 Exhaust system 2a to 2c Vacuum pump 3a to 3c Inverter circuit 4 Connection piping 5 Vacuum pressure sensor 6 Control unit 7 Storage unit 10 Displacement adjustment processing P2a to P2c Power S3a to S3c Control signal S5 Sensor signal D Control data X Exhaust subject

Claims (4)

N units (N is a natural number of 2 or more) of N units (N is a natural number of 2 or more) that are configured to be able to exhaust gas from the exhaust target and are connected in parallel to the exhaust target via a connection pipe, and
A vacuum pressure sensor that detects the vacuum pressure in the connection pipe and outputs a detection signal,
An exhaust system including a control unit that controls the operation of each exhaust device so that the vacuum pressure in the connection pipe specified based on the detection signal becomes a vacuum pressure within a pressure range specified in advance. There,
At least one of the exhaust devices is composed of a variable exhaust device whose exhaust capacity from the exhaust target changes according to the number of revolutions.
In a state where the plurality of exhaust devices including the variable exhaust device are operated, the control unit keeps the vacuum pressure in the connection pipe specified based on the detection signal within the predetermined pressure range. When the temperature becomes constant, the amount of exhaust gas from the object to be exhausted is equal to or less than the predetermined amount of exhaust gas, based on the number of rotations of the variable exhaust device in operation and the vacuum pressure in the connection pipe. It is determined whether or not the variable exhaust device operating in the reduced exhaust capacity state exists, and when the variable exhaust device operating in the reduced exhaust capacity state exists, at least one unit is present. An exhaust system that stops at least one variable exhaust device that is operating in a state of reduced exhaust capacity while continuing the operation of the exhaust device. In the control unit, there are a plurality of the variable exhaust devices operating in the exhaust capacity reduced state, and the number of rotations of each of the variable exhaust devices operating in the exhaust capacity reduced state is other. When the variable exhaust device having a rotation speed different from that of the variable exhaust device exists, the variable exhaust device having the highest rotation speed among the variable exhaust devices operating in the reduced exhaust capacity state. The exhaust system according to claim 1, wherein at least one of the variable exhaust devices excluding the above is stopped. N units (N is a natural number of 2 or more) that are configured to be able to exhaust gas from the exhaust target and are connected in parallel to the exhaust target via the connection pipe, and the vacuum pressure in the connection pipe. Targeting an exhaust system equipped with a vacuum pressure sensor that detects and outputs a detection signal, the vacuum pressure in the connection pipe specified based on the detection signal is within a predetermined pressure range. It is an exhaust device control method that controls the operation of each of the exhaust devices so as to be.
In the exhaust system in which at least one of the exhaust devices is a variable exhaust device in which the exhaust capacity from the exhaust target changes according to the number of revolutions, the plurality of exhausts including the variable exhaust device. The variable exhaust device in operation when the vacuum pressure in the connection pipe specified based on the detection signal becomes constant within the pressure range specified in advance in the state where the device is operated. Based on the number of revolutions and the vacuum pressure in the connection pipe, the variable exhaust device operating in a reduced exhaust capacity state in which the exhaust amount of the gas from the exhaust target is equal to or less than a predetermined exhaust amount. In addition to determining whether or not it exists, when the variable exhaust device operating in the exhaust capacity reduced state exists, at least one of the exhaust devices continues to operate in the exhaust capacity reduced state. An exhaust device control method for stopping at least one of the variable exhaust devices in operation. There are a plurality of the variable exhaust devices operating in the reduced exhaust capacity state, and each of the variable exhaust devices operating in the reduced exhaust capacity state has a rotation speed of another variable exhaust device. When the variable exhaust device having a different rotation speed exists, the variable type excluding the variable exhaust device having the highest rotation speed among the variable exhaust devices operating in the reduced exhaust capacity state. The exhaust device control method according to claim 3, wherein at least one of the exhaust devices is stopped.

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