JP2020101156A - Exhaust system and exhaust device control method - Google Patents

Abstract

To further reduce power consumption.SOLUTION: When vacuum pressure inside connection piping identified on the basis of a detection signal is stabilized within a preliminarily designated pressure range with a plurality of exhaust devices including variable exhaust devices operated by a control section (Steps 12 and 14), on the basis of the number of rotations of the active variable exhaust devices and the vacuum pressure inside the connection piping (Step 15), a determination is made as to whether or not the active variable exhaust devices exist in a poor exhaust performance state with an exhaust amount of gas from an exhaust object equal to or lower than a predetermined exhaust amount (Step 16) and, when the active variable exhaust device exists in the poor exhaust performance state, at least one active variable exhaust device is stopped in the poor exhaust performance state while maintaining operation of at least one exhaust device (Step 17).SELECTED DRAWING: Figure 2

Description

The present invention relates to an exhaust system including 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 target such as an injection molding machine or an adsorption holding device, and a control method thereof. It is disclosed in. The exhaust system disclosed by the applicant is provided with a plurality of vacuum pumps (exhaust capacity variable type vacuum pumps) powered by a motor (electric motor) operated by electric power supplied from an inverter circuit, and these vacuum pumps are used. The pump is connected in parallel to the exhaust target via a connecting pipe.

In this exhaust system, the control unit specifies the vacuum pressure in the connecting pipe based on the sensor signal from the pressure sensor arranged in the connecting pipe, and the specified vacuum pressure is allowable for the target vacuum pressure. By controlling each inverter circuit so that the vacuum pressure is within the range, control is performed to change the power supply state to each vacuum pump (that is, the number of vacuum pumps to be operated and the rotation speed of the vacuum pumps in operation). To do. As a result, in this exhaust system, the number of vacuum pumps required to bring the vacuum pressure in the connecting pipe to a pressure within the allowable range with respect to the target vacuum pressure is operated at the required number of revolutions, and an appropriate amount of exhaust gas is exhausted from the exhaust target. Air is continuously exhausted.

JP-A-2015-203348 (page 12-28, FIG. 1-6)

However, the exhaust system and the control method thereof disclosed by the applicant have the following problems to be improved. Specifically, in the exhaust system and the control method disclosed by the applicant, the control unit controls the vacuum pump to operate such that the vacuum pressure in the connecting pipe is within a permissible range with respect to the target vacuum pressure. A configuration and a control method are adopted in which the operating state of each vacuum pump is controlled by defining the number of units and the number of rotations of the vacuum pumps in operation (for example, the number of rotations of a motor mounted as a power source in the vacuum pumps). ing.

Thus, in the exhaust system and control method disclosed by the applicant, the control unit determines the number of vacuum pumps to operate when the load increases (when a large amount of air needs to be exhausted from the exhaust target). It is possible to maintain the vacuum pressure in the connecting pipe within a permissible range with respect to the target vacuum pressure by increasing or increasing the rotation speed of the vacuum pump during operation. Further, in the exhaust system and control method disclosed by the applicant, the control unit reduces the number of vacuum pumps to be operated when the load decreases (when the amount of air to be exhausted from the exhaust target decreases). It is possible to maintain the vacuum pressure in the connecting pipe within a permissible range with respect to the target vacuum pressure by controlling the rotation speed of the vacuum pump 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 rises due to the exhaustion by the vacuum pump during continuous operation, the rotation speed of those vacuum pumps is reduced to reduce the unit from the exhaust target. The vacuum pressure in the connection pipe is reduced by reducing the amount of air exhausted per unit of time, and the vacuum pressure in the connection pipe is reduced to the target vacuum pressure even when the rotation speed has been reduced to a specified value. When it is higher than the allowable range for (i.e., when the exhaust amount of air per unit time from the exhaust target 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 to maintain the vacuum pressure in the connecting pipe within the allowable range with respect to the target vacuum pressure.

On the other hand, in the vacuum pump used in this type of exhaust system, as shown in FIG. 4, the attainable vacuum pressure (hereinafter, also referred to as “reachable vacuum pressure”) changes according to the rotation speed. In the figure, the upper limit rotation speed of the allowable range is set to 100.0%, the lower limit rotation speed of the allowable range is set to 33.3%, and five types of rotation speeds including the upper limit rotation speed and the lower limit rotation speed are set. Taking the number as an example, the relationship between the exhaust amount from each exhaust target (volume of air at 1 atmospheric pressure exhausted from the vacuum pump) and the vacuum pressure in the connecting pipe is illustrated for each rotation speed. There is. That is, in the vacuum pump of the example shown in the same drawing, the vacuum pressure a at which the displacement is minimum when operated at a rotation speed of 100.0% is the attainable vacuum pressure at a rotation speed of 100.0%, The vacuum pressure e at which the exhaust amount is minimum when operated at the rotation speed of 33.3% is the attainable vacuum pressure at the 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 the three vacuum pumps are operated. Gradually reduce the rotation speed of each vacuum pump, and even if the rotation speed is reduced to 66.7%, if the vacuum pressure in the connecting pipe is higher than the allowable range for the target vacuum pressure, three vacuum pumps A configuration is adopted in which one of the two vacuum pumps is stopped while the other is continuously operated.

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 attainable vacuum pressure when each vacuum pump is operated at the rotation speed of 66.7%. When the load decreases while the rotation speed of each vacuum pump is 66.7% or more, the vacuum pressure in the connecting pipe becomes higher than the target vacuum pressure. Even if the pressure is reduced to 0.7%, the vacuum pressure in the connecting pipe becomes 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 operation of the three units, and in order to further reduce the vacuum pressure, The process of stopping one of the vacuum pumps is performed.

However, for example, when 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 attainable vacuum pressure when the vacuum pump is operated at a rotation speed of 66.7%), 3 When the load is reduced while operating the vacuum pumps of the units, when the rotation speed of each vacuum pump is reduced to 83.3%, the vacuum pressure in the connecting pipe is 83.3%. Since the vacuum pressure b is the attainable vacuum pressure and the target vacuum pressure at the rotation speed of, the rotation speed of each vacuum pump is not further reduced and the rotation speed of 83.3% is maintained. 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, while the target vacuum pressure is set to the vacuum pressure. When set to a pressure 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 the rotation speed of 83.3% and the vacuum pressure b is maintained. In the state, as shown in FIG. 4, a state in which the exhaust amount by each vacuum pump is extremely small, that is, a state similar to that in which each vacuum pump is not substantially functioning is maintained.

On the other hand, since the vacuum pressure b set as the target vacuum pressure is the attainable vacuum pressure when the rotation speed of each vacuum pump is 83.3%, it is possible to operate the three vacuum pumps without operating. It can be reached by operating one vacuum pump at a rotation speed of 83.3%. Nevertheless, it is difficult to reduce the power consumption of the exhaust system because each vacuum pump, which is virtually not functioning, is continuously operated at a high rotation speed of 83.3%. .. Therefore, it is preferable to improve the power consumed in the state as in the above example so that the power can be reduced.

The present invention has been made in view of such problems to be improved, and a main 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 to be capable of exhausting gas from an exhaust target and connected in parallel to the exhaust target through a connecting pipe (N is 2 or more). (A natural number), an exhaust device, a vacuum pressure sensor that detects a vacuum pressure in the connection pipe and outputs a detection signal, and a vacuum pressure in the connection pipe that is specified based on the detection signal is designated 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 a predetermined pressure range, wherein at least one of the exhaust devices has the exhaust gas according to a rotation speed. The control unit is configured by a variable exhaust device having a variable exhaust capacity, and in a state in which a plurality of exhaust devices including the variable exhaust device are operated, the control unit is specified based on the detection signal. When the vacuum pressure in the connecting pipe becomes constant within the predetermined pressure range, the exhaust is performed based on the rotation speed of the variable exhaust device in operation and the vacuum pressure in the connecting pipe. The exhaust amount of the gas from the target is determined to be equal to or less than the predetermined exhaust amount, and it is determined whether or not the variable exhaust device is operating in the exhaust capacity lowering state, and is operating in the exhaust capacity lowering state. When the variable exhaust device is present, at least one variable exhaust device operating in the reduced exhaust capacity state is stopped while continuing the operation of at least one exhaust device.

The exhaust system according to claim 2 is the exhaust system according to claim 1, wherein the control unit includes a plurality of the variable exhaust devices that are operating in the exhaust capacity lowering state, and in the exhaust capacity lowering state. When there is a variable exhaust device in which the number of revolutions is different from the number of revolutions of the other variable exhaust device in operation, the variable exhaust device in operation is in operation in the reduced exhaust capacity state. At least one of the variable exhaust devices excluding 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, wherein N (N is a natural number of 2 or more) exhaust devices that are configured to be capable of exhausting gas from an exhaust target and are connected in parallel to the exhaust target via a connecting pipe. And a vacuum pressure in the connection pipe specified based on the detection signal, with an exhaust system including a vacuum pressure sensor that detects a vacuum pressure in the connection pipe and outputs a detection signal as a control target. Is an exhaust device control method for controlling the operation of each of the exhaust devices so that the exhaust pressure becomes a vacuum pressure within a predesignated pressure range, wherein at least one of the exhaust devices has the exhaust gas according to the number of revolutions. In the exhaust system composed of a variable exhaust device whose exhaust capacity from a target changes, in a state where a plurality of the exhaust devices including the variable exhaust device are operated, the exhaust system is specified based on the detection signal. When the vacuum pressure in the connecting pipe becomes constant within the predetermined pressure range, the exhaust is performed based on the rotation speed of the variable exhaust device in operation and the vacuum pressure in the connecting pipe. The exhaust amount of the gas from the target is determined to be equal to or less than the predetermined exhaust amount, and it is determined whether or not the variable exhaust device is operating in the exhaust capacity lowering state, and is operating in the exhaust capacity lowering state. When the variable exhaust device is present, at least one variable exhaust device operating in the reduced exhaust capacity state is stopped while continuing the operation of at least one exhaust device.

The exhaust device control method according to claim 4 is the exhaust device control method according to claim 3, wherein there are a plurality of the variable exhaust devices that are operating in the exhaust capacity lowering state, and operate in the exhaust capacity lowering state. When there is the variable exhaust device whose rotation speed is different from the rotation speed of the other variable exhaust device in each of the variable exhaust devices in the inside, At least one of the variable exhaust devices excluding the variable exhaust device having the highest rotation speed among the variable exhaust devices is stopped.

Note that the above "when the vacuum pressure in the connecting pipe becomes constant within a predesignated pressure range" means that the state in which the vacuum pressure in the connecting pipe does not deviate from the predesignated pressure range. When maintained" means. Therefore, "when the vacuum pressure in the connecting pipe fluctuates slightly without deviating from the predesignated pressure range", "the vacuum pressure in the connecting pipe becomes constant within the predesignated pressure range" Included in "when".

In the exhaust system according to claim 1 and the exhaust device control method according to claim 3, in the connection pipe specified based on the detection signal in a state in which a plurality of exhaust devices including a variable exhaust device are operated. When the vacuum pressure becomes constant within the pre-specified pressure range, the amount of gas exhausted from the exhaust target is preset based on the rotation speed of the operating variable exhaust device and the vacuum pressure in the connecting piping. It is determined whether or not there is a variable exhaust system that is operating in an exhaust capacity lowering state that is less than or equal to the specified exhaust volume, and at least when there is a variable exhaust system that is operating in an exhaust capacity lowering state. While continuing the operation of one exhaust device, at least one variable exhaust device that is operating in a state in which the exhaust capacity is lowered 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 of the exhaust devices is operated while the plurality of exhaust devices are operating. , When the exhaust amount of air 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 the operating exhaust devices are in the exhaust capacity degraded state. Unnecessary variable exhaust system that is not functioning is stopped until it becomes a state where the exhaust system consumes only 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 type exhaust devices that are operating in a reduced exhaust capacity state, and each variable type that is operating in a reduced exhaust capacity state. When there is a variable exhaust system in the exhaust system whose rotational speed is different from the rotational speed of other variable exhaust systems, the rotational speed of each variable exhaust system that is operating in a state of reduced exhaust capacity is At least one of the variable exhaust devices except the highest variable exhaust device is stopped.

Therefore, according to the exhaust system of the second aspect and the exhaust system control method of the fourth aspect, in a situation where there are a plurality of variable-type exhaust devices operating in the exhaust capacity lowering state, the exhaust capacity lowering state Unlike at least one variable exhaust system that has the highest rotation speed among all operating variable exhaust systems that is operating, when at least one variable exhaust system that is operating in a reduced exhaust capacity state is stopped In addition, without increasing the rotation speed of the variable exhaust system in operation or restarting the operation of the variable exhaust system that was stopped, Only by maintaining the operating state (rotation speed) of the variable exhaust system with the highest rotation speed, the vacuum pressure within the allowable range for the target vacuum pressure, which is the attainable 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. 6 is a flowchart of an exhaust amount adjustment process 10 executed by a control unit 6 in the exhaust system 1 according to the embodiment of the present invention. It is explanatory drawing for demonstrating an example of the operating state of the vacuum pumps 2a-2c at the time of execution of the exhaust amount adjustment process 10 by the exhaust system 1 which concerns on embodiment of this invention. In the exhaust system 1 according to the embodiment of the present invention, the relationship between the “exhaust amount from the exhaust target X” and the “vacuum pressure” of each of the vacuum pumps 2a to 2c is determined for each rotation speed of 33.3% to 100.0%. It is a figure shown for every number of rotations.

Embodiments of an exhaust system and an exhaust device control method will be described below 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 similar to the above-described 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 such 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)" and inverter circuits 3a to 3c ( Hereinafter, when these are not distinguished, they are also referred to as "inverter circuit 3"), a connecting 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” that is an example of a “variable exhaust device in which the exhaust capacity from an exhaust target changes according to the number of revolutions”, and in the exhaust system 1 of this example, The vacuum pump 2 is connected in parallel to the exhaust target X via a connection pipe 4 (an example of “connection pipe”). As an example, the vacuum pump 2 is configured by a rotor type pump (rotary pump) such as a vane pump, and power P2a to P2c supplied from each inverter circuit 3 (hereinafter, when no distinction is made, as will be described later). A motor that rotates at a rotation speed (rotation speed) according 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 are connected to a power transmission mechanism (coupling or coupling). , Belts & pulleys, etc.).

That is, in the vacuum pump 2 of this example, the rotation speed of the motor (rotation speed of the power output shaft) and the rotation speed of the input shaft of the pump body (rotation speed of the rotor) are fixed at a predetermined ratio. The rotation speed of the rotor changes according to the increase or decrease in the rotation speed of the motor. In the following description, in order to facilitate understanding of the operation of the exhaust system 1, the “rotation speed of the power output shaft in the motor mounted in the vacuum pump 2” is simply referred to as the “rotation speed of the vacuum pump 2”. Say. In this case, as an example, the exhaust system 1 of this example includes motors each 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.

It should be noted that a “variable exhaust device” such as the vacuum pump 2 is in a state where it is difficult to sufficiently exhaust air (suction air) in an operating state in which the rotational speed is lower than a predetermined rotation speed. Therefore, in this example, as an example, when the rotation speed when the electric power P2 of the above-mentioned rated frequency (60 Hz) is supplied to each vacuum pump 2 is set to 100.0% of the upper limit, 33 The rotation speed of 0.3% is specified as the lower limit, and it is specified that each vacuum pump 2 is operated at the rotation speed of between 33.3% and 100.0%. In each vacuum pump 2 used in the exhaust system 1 of this example, the relationship between the “exhaust amount from the exhaust target X” and the “vacuum pressure” for each rotation speed is as shown in FIG. The exhaust capacity is

The inverter circuit 3 constitutes a “control unit” together with the control unit 6. In this case, in the exhaust system 1 of the present 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 causes the control signal S3b from the control unit 6. In accordance with the above, the frequency of the power P2b supplied to the vacuum pumps 2b is changed, and the frequency of the power P2c supplied to the vacuum pumps 2c is changed by the inverter circuit 3c in accordance with the control signal S3c from the control unit 6. 33.3% to 100.0% of the rotation speed of each vacuum pump 2 is controlled (the rotation speed of each vacuum pump 2 is controlled).

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

The connection pipe 4 is a pressure pipe that connects the respective vacuum pumps 2 in parallel to the exhaust target X, and in the exhaust system 1 of this example, a vacuum pressure sensor 5 is attached to the connection pipe 4. There is. Instead of the configuration of the exhaust system 1 including the connecting 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 for arranging (a configuration using “connection piping” 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 connecting pipe 4 as described above and detects the vacuum pressure (vacuum degree) in the connecting pipe 4. , And outputs a sensor signal S5 (an example of “detection signal”) corresponding to the detected vacuum pressure.

As described above, the control unit 6 constitutes a “control unit” together with each inverter circuit 3, and controls the exhaust system 1 as a whole. As will be described later, the control unit 6 executes the exhaust amount adjustment processing 10 shown in FIG. 2 to control the inverter circuits 3 with control signals S3a to S3c (hereinafter, also referred to as "control signal S3" when no distinction is made). ) Is output, the vacuum pressure in the connecting pipe 4 is within a permissible range (for example, a range of ±5.0% of the set target vacuum pressure) with respect to a preset target vacuum pressure. Each vacuum pump 2 is operated so that

Specifically, the control unit 6 identifies the vacuum pressure in the connecting pipe 4 based on the sensor signal S5 output from the vacuum pressure sensor 5, and determines 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 is higher than the allowable range for the target vacuum pressure (an example of the “prespecified pressure range”), and the allowable limit for the target vacuum pressure is obtained. When the vacuum pressure is lower than the range, it is determined that the load has increased.

Further, when the load decreases, the control unit 6 outputs a control signal S3 to each inverter circuit 3 to change the operating state of each vacuum pump 2 to reduce the exhaust amount 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 inverter circuit 3 to change the operating state of each vacuum pump 2 to increase the exhaust amount of air in the exhaust system 1 as a whole, thereby making it possible to connect. The vacuum pressure in the pipe 4 is maintained within the above vacuum pressure range. Note that the specific content of the exhaust amount adjustment processing 10 by the control unit 6 will be described later in detail.

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

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

When the air is exhausted from the exhaust target X by the exhaust system 1, first, the operation unit (not shown) is operated to set the target vacuum pressure. At this time, in the exhaust system 1 of the present example, as an example, the rotation speed of the vacuum pump 2 supplied with the electric power P2 of 60 Hz is set to 100.0%, and the vacuum pump operated at the rotation speed of 100.0% is used. A target vacuum pressure is specified by designating an arbitrary vacuum pressure within a pressure range having a maximum attainable vacuum pressure of 2 (vacuum pressure a shown in FIG. 4) and a lower limit of 50.0% of the vacuum pressure. 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 a control signal S3a to the inverter circuit 3a to supply electric power P2a of 20 Hz to the vacuum pump 2a (the vacuum pump 2a is operated at a rotation speed of 33.3%). 2), the exhaust amount adjustment process 10 shown in FIG. 2 is started.

In the exhaust amount adjustment process 10, the control unit 6 first specifies 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 a vacuum pressure within an allowable range for the target vacuum pressure (step 12). At this time, since the inside of the connecting pipe 4 is as low as atmospheric pressure immediately after the start of the process, the control unit 6 determines that the vacuum pressure specified based on the sensor signal S5 is higher than the allowable range for the target vacuum pressure. Also determines that the vacuum pressure is low.

Therefore, the control unit 6 outputs the control signal S3a to the inverter circuit 3a to increase the frequency of the power P2a supplied to the vacuum pump 2a, thereby increasing the rotation speed of the vacuum pump 2a (the operation of the vacuum pump). State change: 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 the process, the processes of steps 11 to 13 above are performed until the vacuum pressure specified by 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 amount from the exhaust target X is gradually increased by being repeatedly executed.

Specifically, as shown in the left side of FIG. 3 as a control example of “when the exhaust amount increases (when the vacuum pressure is low)”, first, the rotation speed of the vacuum pump 2a gradually increases from 33.3%. When the temperature is increased 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 exhaust amount of the vacuum pump 2b operating at 33.3% rotation speed. ). This avoids a situation in which the exhaust amount of the exhaust system 1 as a whole rises sharply.

Further, when the rotation speed of the vacuum pump 2a is gradually increased from 66.7% and again rises to 100.0%, the rotation speed of the vacuum pump 2b operating at the rotation speed of 33.3% is gradually increased. 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 in this case, the rotation speed of the vacuum pump 2b is reduced to 66.7% in consideration of the exhaust amount of the vacuum pump 2c operating at the rotation speed of 33.3%. This avoids a situation in which the exhaust amount of the exhaust system 1 as a whole rises sharply.

Further, when the rotation speed of the vacuum pump 2b is gradually increased from 66.7% and rises again to 100.0%, the rotation speed of the vacuum pump 2c operating at the rotation speed of 33.3% is gradually increased. Can be raised. Further, when the rotation speed of the vacuum pump 2b rises to 100.0%, the vacuum pressure is determined until the vacuum pressure specified by 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 each operate at a rotation speed of 100.0% is maintained.

When the volume of the vacuum system in the exhaust system 1, the connection pipe 4 and 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 gas). Before the operation of the vacuum pump 2c (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 a state where only the vacuum pump 2a is operating), the vacuum pressure specified based on the sensor signal S5 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure. In order to facilitate understanding, the vacuum pressure in the connecting pipe 4 is set to the target vacuum pressure before the three vacuum pumps 2a to 2c are in a state of operating at a rotation speed of 100.0% as described above. It is assumed that the vacuum pressure within the allowable range has not been reached. Further, instead of the example of the control described above, when starting the exhaust system 1, it is possible to simultaneously start the operation of a plurality of vacuum pumps 2 immediately after the start of the process, but the description of the example of such control is omitted.

Further, in the present example in which the target vacuum pressure set prior to the start of the process is the vacuum pressure e, for example, when the exhaust target X is in a non-operating state and the load is small, the vacuum pumps 2a to 2c are operated as described above. The three units each exhaust air from the exhaust target X at a rotation speed of 100.0%, so that the vacuum pressure in the connecting pipe 4 (the vacuum pressure specified based on the sensor signal S5 from the vacuum pressure sensor 5). Rises to the vacuum pressure e. Further, when the three vacuum pumps 2 are continuously operated at the rotation speed of 100.0%, the vacuum pressure in the connecting pipe 4 can reach at the rotation speed of 100.0% of each vacuum pump 2. The 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 the rotation speed of 100.0%, the vacuum pressure in the connection pipe 4 specified based on the sensor signal S5 in step 11 is equal to the target vacuum pressure. The vacuum pressure is identified to be higher than the allowable range for (step 12).

At this time, the control unit 6 outputs the control signal S3c to the inverter circuit 3c to decrease the frequency of the power P2c supplied to the vacuum pump 2c, thereby decreasing the rotation speed of the vacuum pump 2c (vacuum pump 2c). Change of operating state: Step 13), the exhaust amount from the exhaust target X by the vacuum pump 2c is reduced, and the process returns to Step 11. Next, the processes of steps 11 to 13 described above are repeatedly executed until the vacuum pressure specified by 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 engine displacement 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 is gradually changed from 100.0%. When the rotation speed of the vacuum pump 2c is lowered to 33.3%, which is the lower limit value of the rotation speed, the rotation speed of the vacuum pump 2c is maintained at 33.3%, and the rotation speed 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 exhaust amount is reduced by stopping the vacuum pump 2c operating at the rotation speed of 33.3%. Considering this, 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 drops sharply.

Further, when the rotation speed of the vacuum pump 2b is gradually decreased from 100.0% to 33.3% which is the lower limit value 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 decreased from 100.0%. When the rotation speed of the vacuum pump 2a drops to 66.7%, the vacuum pump 2b is stopped, and the exhaust amount is reduced by stopping the vacuum pump 2b that was operating at 33.3%. Considering this, 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 drops sharply.

When the rotation speed of the vacuum pump 2a is gradually decreased from 100.0% to 33.3% which is the lower limit value of the rotation speed, the connection pipe 4 specified based on the sensor signal S5. The internal vacuum pressure becomes the vacuum pressure e, which is the vacuum that can be reached by the vacuum pump 2a rotated at 33.3%. Therefore, the control unit 6 determines that the vacuum pressure in the connecting pipe 4 identified in Step 11 is within the allowable range with respect to the set target vacuum pressure (Step 12), and a plurality of vacuum units are vacuumed. It is determined whether or not the pump 2 is in operation (step 13).

At this time, since only one of the vacuum pumps 2a is in operation, the control unit 6 returns to step 11 and identifies the vacuum pressure in the connecting pipe 4 based on the sensor signal S5. After that, the processes of steps 11 to 14 described above 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 the exhaust process at the 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 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. In this state, when the start of the exhaust process is instructed by the operation of the operation unit, the control unit 6 first gradually raises the rotation speed of the vacuum pump 2a in the same manner as in the control example described above, and then the vacuum pump 2a is rotated. In addition to the pump 2a, the operation of the vacuum pump 2b is started to gradually increase its rotation speed, and the operation of the vacuum pump 2c in addition to the vacuum pumps 2a and 2b is started to gradually increase its rotation speed. Let As a result, the three vacuum pumps 2a to 2c are in a state of operating at a rotation speed of 100.0%.

Further, when the three vacuum pumps 2 are continuously operated at the rotation speed of 100.0%, the vacuum pressure in the connecting pipe 4 can reach at the rotation speed of 100.0% of each vacuum pump 2. The 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 the rotation speed of 100.0%, the vacuum pressure in the connection pipe 4 specified based on the sensor signal S5 in step 11 is equal to the target vacuum pressure. The vacuum pressure is identified to be higher than the allowable range for (step 12).

At this time, similarly to the above-described 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 decreased from 100.0% to 33.3%. While the state is maintained, the rotation speed of the vacuum pump 2b is gradually decreased from 100.0%, and when the rotation speed of the vacuum pump 2b is decreased to 66.7%, the vacuum pump 2c is stopped. The rotation speed of the vacuum pump 2b can be increased to 100.0%. Then, the rotation speed of the vacuum pump 2b is gradually decreased from 100.0% to maintain the state of 33.3%, and the rotation speed of the vacuum pump 2a is gradually decreased from 100.0%.

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

On the other hand, in the exhaust system 1 of the present example, as described above, after it is determined in step 12 that the vacuum pressure in the connecting pipe 4 is within the allowable range for the target vacuum pressure, The vacuum pumps 2 (in this example, the vacuum pumps 2a and 2b) are determined to be in operation (step 14), and the operating state of the vacuum pump 2 in operation at that time is specified (step 15). At this time, the control unit 6 specifies 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 exhaust amount of the air from the exhaust target X based on the identified rotation speed of each vacuum pump 2 and the vacuum pressure in the connection pipe 4 identified in step 11. It is determined whether or not there is the vacuum pump 2 in operation in the following "exhaust capacity lowering state" (step 16).

In this case, as shown in FIG. 4, the ultimate vacuum degree of the vacuum pump 2b operating at the rotation speed of 33.3% is the ultimate vacuum degree of the vacuum pump 2a operating at the rotation speed of 83.3%. Therefore, the degree of vacuum e is lower than the degree of vacuum b, which is the target degree of vacuum. Therefore, in the vacuum pump 2b, the degree of vacuum in the connecting pipe 4 is higher than the attainable degree of vacuum at the time of operation at the rotation speed of 33.3%. Has a very small displacement (substantially zero). In the exhaust system 1 of the present example, as an example, an operating state in which the exhaust amount from the exhaust target X is equal to or less than the exhaust amount A in FIG. A configuration is adopted in which the vacuum pump 2 that does not contribute to proper exhaust processing is stopped.

In this case, the exhaust amount (“exhaust amount A” in the above example) to be in the “exhaust capacity lowering state” can be arbitrarily changed by operating the operation unit (not shown). In addition, at what vacuum pressure and at what speed the vacuum pump 2 is operated, what is the exhaust volume of the vacuum pump 2 (what rotation speed under the current vacuum pressure? Whether the exhaust amount by the vacuum pump 2 is equal to or less than the “exhaust amount A” when operated in (3), the control data D capable of specifying the relationship therebetween is stored in the storage unit 7. Therefore, the control unit 6 determines the vacuum pumps 2a and 2b based on the vacuum pressure identified in step 11, the rotation speed of the vacuum pumps 2a and 2b identified in step 15, and the control data D stored in the storage unit 7. Determines whether or not is operating in the “exhaust capacity lowering state”.

Specifically, for the vacuum pump 2b operating at a rotation speed of 33.3%, the control unit 6 determines that the vacuum pressure e that is the attainable vacuum pressure is the vacuum pressure (target vacuum pressure) specified in step 11. Is lower than the vacuum pressure b within a permissible range) and the amount of exhaust from the exhaust target X is smaller than the exhaust amount A (exhaust capacity lowering state). "When there is a variable exhaust device that is operating in a reduced capacity state": step 16). Further, the control unit 6 also causes the exhaust amount from the exhaust target X to be smaller than the exhaust amount A under the vacuum pressure specified in step 11, even for the vacuum pump 2a operating at the rotation speed of 83.3%. It is determined that the engine is operating in the “exhaust capacity lowering state” (another example of the state “when there is a variable exhaust device operating in the lower exhaust capacity state”: step 16).

Next, the control unit 6 determines that both of the operating vacuum pumps 2a and 2b are operating in the “exhaust capacity lowering state” (there are a plurality of variable exhaust devices operating in the “exhaust capacity lowering state”). , And when there is a variable exhaust device in which the rotational speed is different from the rotational speeds of other variable exhaust devices in each of the variable exhaust devices that are operating in a state in which the exhaust capacity is reduced”), An example of the 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 the variable exhaust devices operating in a state where exhaust capacity is reduced”) ) Stop.

Specifically, the control unit 6 stops the vacuum pump 2b by outputting the control signal S3b to the inverter circuit 3b to stop the output of the power P2b to the vacuum pump 2b (“at least one exhaust gas is exhausted”). While continuing the operation of the device, at least one variable exhaust device that is operating in the exhaust capacity lowering state is stopped". As a result, the power consumption of the exhaust system 1 is reduced by the amount of the power P2b supplied to the stopped vacuum pump 2b.

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

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

In addition, a basic control procedure for changing the number of revolutions of each vacuum pump 2 and the number of operating pumps according to the vacuum pressure in the connecting pipe 4 specified based on the sensor signal S5 (each of steps 11 to 13). The processing procedure) is not limited to the example of the control procedure shown in FIG. For example, the applicant can change the operating state of each vacuum pump 2 by adopting the same procedure as the control procedure of each embodiment of the exhaust system and the control method disclosed in the above-mentioned patent document.

In this case, when the control procedure in which the rotational speeds of the vacuum pumps 2 in operation are set to the same rotational speed as each other 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 while operating 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 each of the vacuum pumps 2a to 2c is operated at a rotation speed of 83.3% while the vacuum pressure in the connecting pipe 4 is the vacuum pressure b, the exhaust amount of each of the vacuum pumps 2a to 2c is This is a state in which the displacement A is significantly below.

At this time, it is determined that all of the vacuum pumps 2a to 2c are in the "exhaust capacity lowering state" based on the rotational speed of the vacuum pump 2 in operation and the vacuum pressure in the connecting pipe 4 ("exhaust capacity"). There is a plurality of variable exhaust devices that are operating in a state of reduced capacity.” Another example of the state). In such a state, unlike the above-described example, all the rotation speeds of the vacuum pumps 2a to 2c operating in the "exhaust capacity lowering state" are the same rotation speed. Therefore, among the vacuum pumps 2, the vacuum pumps 2 having a low “priority order for operating” are 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 order to be the operation state", first, among the vacuum pumps 2a to 2c in the "exhaust capacity lowering state". The vacuum pump 2c is stopped and the vacuum pumps 2a and 2b are continuously operated at a rotation speed of 83.3% (“While the operation of at least one exhaust device is continued, the variable operation is performed in the exhaust capacity lowering state”. Another example of a process of "stopping at least one die exhaust device"). Next, even after the vacuum pump 2c is stopped, the vacuum pump 2b of the vacuum pumps 2a and 2b that is in the “exhaust capacity lowering state” is stopped, and the vacuum pump 2a is continuously operated at a rotation speed of 83.3% (“ Still another operation of at least one variable exhaust device that is operating in a state in which the exhaust capacity is lowered while continuing the operation of at least one exhaust device”.

As a result, the vacuum pumps 2b and 2c are stopped from the state in which the three vacuum pumps 2a to 2c are operated at the rotation speed of 83.3%, and only one of the vacuum pumps 2a has the speed of 83.3%. A state in which the vacuum pressure in the connecting pipe 4 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure is maintained while operating at the rotation speed. As described above, in place 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 lowering state" (for example, vacuum pumps) It is also possible to perform 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 within the allowable range for the target vacuum pressure. The pressure condition is maintained.

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

Therefore, according to the exhaust system 1 and the exhaust device control method, any one (or all) of the plurality of vacuum pumps 2 is operated while the plurality of vacuum pumps 2 are operating. When only a small amount of "is exhausted," the vacuum pump 2 is operating, or all the operating vacuum pumps 2 are "exhausted Since the unnecessary vacuum pump 2 that is not substantially functioning is stopped until the state is not reached, the power consumption of the exhaust system 1 is reduced by the amount of the power P2 supplied to the stopped vacuum pump 2. Can be reduced. Thereby, the running cost of the exhaust system 1 can be further reduced.

Further, in the exhaust system 1 and the exhaust device control method, there are a plurality of vacuum pumps 2 operating in the “exhaust capacity lowering state”, and among the vacuum pumps 2 operating in the “exhaust capacity lowering state”. When there is a vacuum pump 2 whose rotational speed is different from the rotational speeds of the other vacuum pumps 2, the vacuum pump 2 with the highest rotational speed is selected from among the vacuum pumps 2 that are operating in the “exhaust capacity lowering state”. At least one of the vacuum pumps 2 to be removed is stopped.

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

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

Further, as an example of the “variable exhaust device”, the rotation speed of each vacuum pump 2 is changed by changing the frequency of the electric power supplied from the inverter circuit 3 by adopting the vacuum pump 2 using an inverter control type motor as a power source. Although the configuration and method for controlling the engine have been described as an example, for example, a voltage variable control type “variable exhaust device” using a motor whose power source is a motor whose rotation speed changes according to the voltage of the supplied power is adopted. , Adopting a configuration/method that controls the rotation speed by changing the voltage of the power supplied to the "exhaust device", or changing the current using a motor whose power source changes the rotation speed as a power source. It is also possible to employ a control type “variable exhaust device” and adopt a configuration/method for controlling the rotation speed by changing the current of the electric power supplied to the “exhaust device”.

Further, the configuration in which the vacuum pump 2 having a motor (electric motor) as a power source is provided as an “exhaust device” and the control method thereof has been described, but the “internal combustion engine” or the “steam turbine” is used as a power source. It is also possible to configure an "exhaust system" by providing an "exhaust device" and control those "exhaust devices" to exhaust gas (air or the like) from the "exhaust target".

Furthermore, 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, belt & pulley, etc., and the rotation speed of the power source (the rotation speed of the power output shaft). ) And the number of revolutions of the input shaft (the number of revolutions of the rotor) are fixed at a predetermined ratio, the exhaust system 1 has been described as an example. , The input shaft of the pump body is connected to each other through 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 (rotation speed of the rotor) It is also possible to configure by including an “exhaust device” configured to be changeable. In addition, an example in which the rotor type vacuum pump 2 is provided has been described, but a piston and cylinder type “exhaust device” (a reciprocating type “exhaust device” can also be provided. & In the cylinder type “exhaust device”, the rotation speed of the crankshaft to which the piston is connected corresponds to the “exhaust device rotation speed”.

DESCRIPTION OF SYMBOLS 1 Exhaust system 2a-2c Vacuum pump 3a-3c Inverter circuit 4 Connection piping 5 Vacuum pressure sensor 6 Control part 7 Storage part 10 Exhaust amount adjustment process P2a-P2c Electric power S3a-S3c Control signal S5 Sensor signal D Control data X Exhaust Target

Claims (4)

N (N is a natural number of 2 or more) exhaust devices that are configured to be capable of exhausting gas from an exhaust target and are connected in parallel to the exhaust target through a connecting pipe.
A vacuum pressure sensor that detects the vacuum pressure in the connection pipe and outputs a detection signal,
An exhaust system comprising: 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 predetermined pressure range. There
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 control unit, in a state in which a plurality of exhaust devices including the variable exhaust device are operated, the vacuum pressure in the connecting pipe specified based on the detection signal is within the predetermined pressure range. When it becomes constant, the exhaust amount of the gas from the exhaust target is equal to or less than a predetermined exhaust amount based on the rotation speed of the variable exhaust device in operation and the vacuum pressure in the connecting pipe. It is determined whether or not the variable exhaust device is operating in the exhaust capacity lowering state, and at least one of the variable exhaust devices is operating in the exhaust capacity lowering state. An exhaust system that stops at least one variable exhaust device that is operating in the exhaust capacity lowering state while continuing the operation of the exhaust device. The control unit includes a plurality of the variable exhaust devices that are operating in the exhaust capacity lowering state, and the number of rotations is different among the variable exhaust devices that are operating in the exhaust capacity lowering state. When there is the variable exhaust device that is different from the rotational speed of the variable exhaust device, the variable exhaust device that has the highest rotational speed among the variable exhaust devices that are operating in the reduced exhaust capacity state. The exhaust system according to claim 1, wherein at least one of the variable exhaust devices other than the above is stopped. N (N is a natural number of 2 or more) exhaust devices that are configured to be capable of exhausting gas from an exhaust target and are connected in parallel to the exhaust target via a connecting pipe, and a vacuum pressure in the connecting pipe. A vacuum pressure within a predetermined pressure range in which the vacuum pressure in the connection pipe specified based on the detection signal is a control target of an exhaust system including a vacuum pressure sensor that detects and outputs a detection signal. An exhaust system control method for controlling the operation of each exhaust system so that
In the exhaust system, wherein at least one of the exhaust devices includes a variable exhaust device in which the exhaust capacity from the exhaust target changes according to the number of revolutions, in the exhaust system, the plurality of exhaust devices 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 predetermined pressure range in a state in which the device is operated. Based on the number of revolutions and the vacuum pressure in the connection pipe, the variable exhaust device operating in an exhaust capacity lowering state in which the exhaust amount of the gas from the exhaust target is equal to or less than a predetermined exhaust amount, It is determined whether or not the exhaust type is present, and when the variable exhaust device is operating in the exhaust capacity lowering state, the operation of at least one exhaust device is continued while the exhaust type is being lowered. An exhaust system control method for stopping at least one variable exhaust system in operation. There are a plurality of the variable exhaust devices that are operating in the exhaust capacity lowering state, and among the variable exhaust devices that are operating in the exhaust capacity lowering state, the number of rotations of other variable exhaust devices is different. When the variable exhaust device having a different rotational speed from the variable exhaust device exists, the variable type exhaust device excluding the variable exhaust device having the highest rotational speed among the variable exhaust devices operating in the exhaust capacity lowering state. The exhaust system control method according to claim 3, wherein at least one of the exhaust systems is stopped.

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