Vacuum pumping system with a plurality of positive displacement vacuum pumps and method for operating a vacuum pumping system

文档序号：1918357 发布日期：2021-12-03 浏览：19次中文

阅读说明：本技术 具有多个容积式真空泵的真空泵送系统和用于运行真空泵送系统的方法 (Vacuum pumping system with a plurality of positive displacement vacuum pumps and method for operating a vacuum pumping system ) 是由安德莉亚·伯塔洛特罗伯托·卡博里大卫·卢克曼帕斯卡·马丁克里斯蒂安·斯帕达于 2021-05-24 设计创作，主要内容包括：本发明涉及具有多个容积式真空泵的真空泵送系统和用于运行真空泵送系统的方法。本发明涉及一种具有多个容积式真空泵(20、30)以及更特别地并行工作的多个容积式真空泵的真空泵送系统(100),并且涉及一种用于操作这样的真空泵送系统的方法。该真空泵送系统(100)包括管理单元(90),该管理单元对真空泵送系统的所有容积式真空泵进行同步控制,并且因此允许检查真空泵送系统的可能的污染风险,并且如果需要,进行必要的校正动作而不需要对真空泵送系统的构造进行任何修改。(The invention relates to a vacuum pumping system having a plurality of positive displacement vacuum pumps and a method for operating a vacuum pumping system. The invention relates to a vacuum pumping system (100) having a plurality of positive displacement vacuum pumps (20, 30) and more particularly a plurality of positive displacement vacuum pumps working in parallel, and to a method for operating such a vacuum pumping system. The vacuum pumping system (100) comprises a management unit (90) which controls all the positive displacement pumps of the vacuum pumping system in synchronism and thus allows to check the vacuum pumping system for possible risks of contamination and, if necessary, to carry out the necessary corrective actions without requiring any modifications to the construction of the vacuum pumping system.)

1. A vacuum pumping system (100) with a plurality of positive displacement vacuum pumps (20, 30), comprising a management unit (90) for controlling the plurality of positive displacement vacuum pumps (20, 30), the plurality of positive displacement vacuum pumps (20, 30) comprising at least two positive displacement vacuum pumps connected to the same vacuum chamber (60) or to mutually communicating vacuum chambers (60, 70), respectively, the management unit (90) being configured to:

-identifying one or more operating parameters of the positive displacement pump, the one or more operating parameters relating to the risk of contamination of the vacuum pumping system by one or more of the positive displacement pumps;

-setting a threshold value or threshold state for each of said identified parameters;

-detecting the identified parameters for each of the positive displacement pumps;

-for each of the positive displacement pumps, comparing a detected value or state of the identified parameter with a corresponding threshold value or state;

-acting in a synchronized manner on at least one other of said plurality of positive displacement pumps (20, 30) if the detected value of one or more identified parameters of one of said positive displacement pumps exceeds said corresponding threshold value or the detected state of one or more identified parameters of one of said positive displacement pumps does not coincide with a corresponding threshold state.

2. A vacuum pumping system as defined in claim 1, wherein the operating parameter is selected from the group consisting of: a pump frequency, a power absorbed by the vacuum pump, a current absorbed by the vacuum pump, a voltage absorbed by the vacuum pump, a temperature of one or more selected components of the vacuum pump.

3. The vacuum pumping system (10) of claim 1, wherein the management unit (90) is configured to at least one of:

-performing a corrective action on two or more of the plurality of positive displacement pumps (20, 30) in a synchronized manner if the detected values of one or more identified parameters of one or more of the positive displacement pumps exceed the corresponding threshold values or the detected states of one or more identified parameters of one or more of the positive displacement pumps do not coincide with corresponding threshold states;

-in case the detected values of one or more identified parameters of one of the positive displacement pumps exceed the corresponding threshold values or the detected states of one or more identified parameters of one of the positive displacement pumps do not coincide with corresponding threshold states, shutting down at least another one of the plurality of positive displacement pumps (20, 30) in a synchronized manner;

-performing a corrective action in a synchronized manner on all of the plurality of positive displacement vacuum pumps (20, 30) in case the detected value of the one or more identified parameters of one of the positive displacement vacuum pumps exceeds the corresponding threshold value or the detected state of the one or more identified parameters of one of the positive displacement vacuum pumps does not coincide with the corresponding threshold state;

-shutting down all of the plurality of positive displacement vacuum pumps (20, 30) in a synchronized manner if the detected values of one or more identified parameters of one of the positive displacement vacuum pumps exceed the corresponding threshold values or the detected status of one or more identified parameters of one of the positive displacement vacuum pumps does not coincide with the corresponding threshold status.

-triggering an alarm if the detected value of one or more identified parameters of one or more of the positive displacement pumps exceeds the corresponding threshold value or the detected status of one or more identified parameters of one or more of the positive displacement pumps does not coincide with a corresponding threshold status.

4. Vacuum pumping system (10) according to any of the claims 1 to 3, wherein the management unit (90) is configured to at least one of:

-detecting the identified parameters and simultaneously comparing the detected values or states of the identified parameters with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps;

-detecting the identified parameters and comparing the detected values or states of the identified parameters with corresponding threshold values or threshold states of the plurality of positive displacement pumps according to a predetermined sequence;

-detecting the identified parameter and continuously comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps;

-detecting the identified parameter and comparing the detected value or state of the identified parameter with corresponding threshold values or states of the plurality of positive displacement pumps at predetermined time intervals.

5. The vacuum pumping system (10) according to any one of the preceding claims, wherein at least one of the positive displacement vacuum pumps is a grease lubricated vacuum pump.

6. The vacuum pumping system (10) of claim 5, wherein the at least one grease lubricated vacuum pump is a rotary vane vacuum pump (20, 30).

7. Vacuum pumping system (10) according to claim 6, wherein the at least one rotary vane vacuum pump (20, 30) comprises a housing receiving a pump body, inside which a stator is defined that surrounds and defines a cylindrical pumping chamber in which a cylindrical rotor is housed and which is positioned eccentrically with respect to the axis of the pumping chamber, one or more radially movable radial vanes being mounted on the rotor and held against the wall of the pumping chamber, a quantity of oil being introduced in the housing for use as a coolant and lubricating fluid, and wherein the management unit (90) is configured to perform at least one of the following actions:

-performing a corrective action on at least one other of the plurality of positive displacement pumps (20, 30) in a synchronized manner if the detected values of one or more identified parameters of one of the positive displacement pumps exceed the corresponding threshold values or the detected status of one or more identified parameters of one of the positive displacement pumps does not coincide with the corresponding threshold status.

-performing a corrective action in a synchronized manner on all of the plurality of positive displacement vacuum pumps (20, 30) in case the detected value of one or more identified parameters of one of the positive displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identified parameters of one of the positive displacement vacuum pumps does not coincide with the corresponding threshold state;

-in case the detected value of one or more identified parameters of one of the positive displacement pumps exceeds the corresponding threshold value or the detected status of one or more identified parameters of one of the positive displacement pumps does not coincide with the corresponding threshold status, then shutting down all positive displacement pumps of the plurality (20, 30) in a synchronized manner.

Thereby preventing oil from the at least one rotary vane vacuum pump from being drawn through the vacuum pumping system by another of the positive displacement pumps.

8. A method of operating a vacuum pumping system (100) having a plurality of positive displacement vacuum pumps (20, 30), the plurality of positive displacement vacuum pumps (20, 30) comprising at least two positive displacement vacuum pumps connected to the same vacuum chamber (60) or to interconnected vacuum chambers (60, 70), respectively, the method comprising the steps of:

-setting a threshold value or threshold state for each of said identified parameters;

-detecting the identified parameters for each of the positive displacement pumps;

-for each of the positive displacement pumps, comparing a detected value or state of the identified parameter with a corresponding threshold value or state;

9. The method of claim 8, wherein the operating parameter is selected from the group consisting of: a pump frequency, a power absorbed by the vacuum pump, a current absorbed by the vacuum pump, a voltage absorbed by the vacuum pump, a temperature of one or more selected components of the vacuum pump.

10. The method of claim 8, wherein the method comprises at least one of:

-in case the detected values of one or more identified parameters of one of the positive displacement pumps exceed the corresponding threshold values or the detected states of one or more identified parameters of one of the positive displacement pumps do not coincide with corresponding threshold states, performing a corrective action in a synchronized manner on at least one other of the plurality of positive displacement pumps (20, 30);

-shutting down at least one other of the plurality of positive displacement pumps (20, 30) in a synchronized manner in case a detected value of one or more identified parameters of one of the positive displacement pumps exceeds the corresponding threshold value or a detected state of one or more identified parameters of one of the positive displacement pumps does not coincide with a corresponding threshold state.

11. The method according to any one of claims 8 to 10, wherein the method comprises at least one of the following steps:

12. A method according to any one of claims 8 to 11, wherein at least one of the positive displacement vacuum pumps is a grease lubricated vacuum pump.

13. The method according to claim 12, wherein the at least one grease lubricated vacuum pump is a rotary vane vacuum pump (20, 30).

14. A method as claimed in claim 13, wherein the at least one rotary vane vacuum pump (20, 30) comprises a housing receiving a pump body, within which is defined a stator surrounding and defining a cylindrical pumping chamber in which is housed a cylindrical rotor and which is positioned eccentrically with respect to the axis of the pumping chamber, one or more radially movable radial vanes being mounted on the rotor and held against the wall of the pumping chamber, a quantity of oil being introduced into the housing to act as a coolant and lubricating fluid, and wherein the method comprises at least one of:

-performing a corrective action in a synchronized manner on all vane rotary vacuum pumps of said plurality of positive displacement vacuum pumps (20, 30) in case the detected value of one or more identified parameters of one of said positive displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identified parameters of one of said positive displacement vacuum pumps does not coincide with the corresponding threshold state;

Thereby preventing oil from the at least one rotary vane vacuum pump from being drawn through the vacuum pumping system by another of the positive displacement pumps.

15. A vacuum pumping system (100), comprising:

at least one interconnected vacuum chamber (60, 70);

a plurality of vacuum pumps (20, 30) each connected to the at least one vacuum chamber (60, 70), respectively, and

a management unit (90) configured to control the operation of the plurality of vacuum pumps (20, 30);

characterized in that the management unit (90) is further operable to monitor one or more operating parameters of the plurality of vacuum pumps (20, 30) and identify a mismatch in expected pumping between the one or more of the plurality of vacuum pumps (20, 30) based on the one or more operating parameters.

16. The vacuum pumping system (100) of claim 15, wherein the at least one interconnected vacuum chamber (60, 70) comprises a plurality of interconnected vacuum chambers (60, 70), and wherein one of the plurality of vacuum pumps (20, 30) is in separate communication with a first vacuum chamber (60, 70) of the plurality of vacuum chambers (60, 70) and another one of the plurality of vacuum pumps (20, 30) is in separate communication with another one of the plurality of vacuum chambers (60, 70).

17. The vacuum pumping system (100) of claim 15 or 16, wherein at least one of the vacuum chambers (60, 70) is in communication with the atmosphere.

18. The vacuum pumping system (100) of any of claims 15 to 17, wherein the management unit (90) is further operable to activate the plurality of vacuum pumps (20, 30) by:

activating a first vacuum pump (20, 30) of the plurality of vacuum pumps (20, 30),

monitoring one or more operating parameters of the first vacuum pump (20, 30),

confirming that the first vacuum pump (20, 30) is operating within an expected pump speed range from the monitoring and activating a second vacuum pump (20, 30) of the plurality of vacuum pumps (20, 30) based on the confirmation;

monitoring one or more operating parameters of the first vacuum pump (20, 30) and the second vacuum pump (20, 30) being operated, while synchronizing the operation of the first vacuum pump (20, 30) and the second vacuum pump (20, 30) to match an expected pump speed of the first vacuum pump (20, 30) and an expected pump speed of the second vacuum pump (20, 30) to prevent backflow from one of the plurality of vacuum pumps (20, 30) into the at least one interconnected vacuum chamber (60, 70).

19. A mass spectrometry system comprising:

a first vacuum chamber for housing a first ion guide configured to receive a plurality of ions generated by an ion source;

a first positive displacement pump configured to maintain the first vacuum chamber at a first operating pressure;

a second vacuum chamber for housing a second ion guide configured to receive at least a portion of the ions transmitted from the first ion guide, wherein the second vacuum chamber is fluidly coupled to the first vacuum chamber,

a second positive displacement pump configured to maintain the second vacuum chamber at a second operating pressure lower than the first operating pressure;

a controller operatively connected to the first positive displacement pump and the second positive displacement pump, wherein the controller is configured to:

monitoring one or more operating parameters of the first and second positive displacement pumps; and is

Identifying a mismatch in expected pumping between the first positive displacement vacuum pump and the second positive displacement vacuum pump based on the one or more operating parameters.

20. The system of claim 19, wherein the controller is further configured to:

identifying one or more operating parameters of the first and second positive displacement pumps, the one or more operating parameters relating to the risk of contamination of the first and second vacuum chambers by one or more of the first and second positive displacement pumps;

setting a threshold value or threshold state for each of the identified parameters;

detecting the identified parameter for each of the first and second positive displacement pumps;

-for each of the first and second positive displacement pumps, comparing a detected value or state of the identified parameter with a corresponding threshold value or state; and is

Acting on one of the first and second positive displacement pumps in a synchronized manner if the detected values of one or more identified parameters of the other of the first and second positive displacement pumps exceed the corresponding threshold values or the detected status of one or more identified parameters of the one of the first and second positive displacement pumps does not coincide with the corresponding threshold status.

21. The system of claim 19, wherein the second vacuum chamber is fluidly coupled to the first vacuum chamber via an aperture in an exit lens of the first vacuum chamber.

22. The system of claim 19, wherein the second positive displacement pump is further configured as a pre-positioned first turbomolecular pump for maintaining a third vacuum chamber at a third operating pressure lower than the second operating pressure, the third vacuum chamber for housing at least a third ion guide.

23. The system of claim 22, wherein the second positive displacement pump is further configured as a pre-positioned second turbo molecular pump for maintaining a fourth vacuum chamber at a fourth operating pressure lower than the third operating pressure, the fourth vacuum chamber for housing at least one mass analyzer.

24. The system of claim 23, wherein the first operating pressure is in a range of about 1 torr to about 100 torr, and optionally wherein the second operating pressure is aboutIn a range of 500 millitorr to about 5 torr, further optionally wherein the third operating pressure is less than about 100 millitorr, and further optionally wherein the fourth operating pressure is less than about 1 x 10^-4And (4) supporting.

25. A method of operating a vacuum system for a mass spectrometry analysis system, comprising:

monitoring one or more operating parameters of a first positive displacement pump configured to maintain a first vacuum chamber at a first operating pressure, wherein the first vacuum chamber houses a first ion guide configured to receive a plurality of ions generated by an ion source;

monitoring one or more operating parameters of a second positive displacement pump configured to maintain a second vacuum chamber at a second operating pressure, wherein the second vacuum chamber houses a second ion guide configured to receive at least a portion of the ions transmitted from the first ion guide; and

identifying a mismatch in expected pumping between the first positive displacement vacuum pump and the second positive displacement pump based on the one or more operating parameters of the first positive displacement pump and the second positive displacement pump.

26. The method of claim 25, further comprising:

identifying the one or more operating parameters of the first and second positive displacement pumps, the one or more operating parameters relating to the risk of contamination of the first and second vacuum chambers by one or more of the first and second positive displacement pumps;

setting a threshold value or threshold state for each of the identified parameters;

detecting the identified parameter for each of the first and second positive displacement pumps;

for each of the first and second positive displacement pumps, comparing a detected value or state of the identified parameter to a corresponding threshold value or state; and

acting on one of the first and second positive displacement pumps in a synchronized manner if the detected values of one or more identified parameters of the other of the first and second positive displacement pumps exceed the corresponding threshold values or the detected status of one or more identified parameters of the one of the first and second positive displacement pumps does not coincide with the corresponding threshold status.

Technical Field

The present invention relates to a vacuum pumping system having a plurality of positive displacement vacuum pumps, and more particularly a plurality of positive displacement vacuum pumps operating in parallel.

The invention also relates to a method for operating a vacuum pumping system having a plurality of positive displacement vacuum pumps, and more particularly a plurality of positive displacement vacuum pumps working in parallel and/or connected to vacuum chambers communicating with each other.

Background

Vacuum pumps are used to achieve a vacuum state, i.e. for evacuating a chamber (the so-called "vacuum chamber") and establishing a sub-atmospheric pressure state in the chamber. Many different types of vacuum pumps are known, having different structures and operating principles, and each time a specific vacuum pump is selected according to the needs of a specific application, i.e. according to the vacuum level to be achieved in the respective vacuum chamber.

Positive displacement pumps displace gas from a sealed region to the atmosphere or a downstream pumping stage.

Positive displacement pumps are very efficient and cost effective in creating low vacuum conditions. For this reason, it can be used as the main pump in a vacuum system, but it is often used as a pressure pump for other pumps, such as turbomolecular pumps.

Unfortunately, in some cases, positive displacement vacuum pumps, such as rotary vane pumps or scroll pumps, may contaminate the vacuum system in which they are installed.

Rotary vane vacuum pumps are contemplated by way of non-limiting example.

Fig. 1 and 2 schematically illustrate a vacuum pumping arrangement 150 comprising a conventional rotary vane vacuum pump 110 and an associated motor 140.

As shown in fig. 1 and 2, a conventional rotary vane vacuum pump 110 generally includes a housing 112 receiving a pump body 114, within which pump body 114 is defined a stator surrounding and defining a cylindrical pumping chamber 116. The pumping chamber 116 houses a cylindrical rotor 118, the rotor 118 being positioned eccentrically with respect to the axis of the pumping chamber 116; one or more radially movable radial vanes 120 (two in the example shown in fig. 2) are mounted on the rotor 118 and are held against the wall of the pumping chamber 116, for example by springs 122.

During operation of the vacuum pump 110, gas flows from the vacuum chamber through the inlet port 124 of the pump and passes through the suction line 126 into the pumping chamber 116, which is pushed by the vanes 120 at the pumping chamber 116 and is thus compressed, and which is then evacuated through the evacuation line 128 terminating at the corresponding outlet port 130.

An appropriate amount of oil is introduced into the housing 112 from an oil tank (not shown) to serve as a coolant and a lubricating fluid. In the example shown in fig. 2, for example, the inner shell 114 is submerged in an oil sump 132.

The vacuum pumping arrangement 150 further comprises a motor 140 for driving the rotor 118 of the vacuum pump, and the pump rotor 118 is mounted to a rotating shaft driven by said motor.

As described above, in a rotary vane vacuum pump, oil is used to lubricate and cool moving parts of the pump. In this type of pump, the oil also acts as a sealant for providing a seal between the regions at different pressures.

At the inlet of the vacuum pump there is a risk that oil vapour causes backflow and contaminates the vacuum chamber evacuated by the vacuum pump.

This risk is higher in vacuum pumping systems in which there are two or more rotary vane vacuum pumps working in parallel and/or connected to vacuum chambers communicating with each other.

Indeed, in such complex vacuum pumping systems, if one of the rotary vane vacuum pumps is stopped due to a failure, the other rotary vane vacuum pump of the vacuum pumping system can suck the oil vapor at the inlet of the vacuum pump that has been stopped. The pumped oil is thus passed through the vacuum chamber to which the vacuum pump is connected, and the net effect is to contaminate the vacuum pumping system.

In order to prevent contamination of the vacuum chamber, the positive displacement vacuum pump, such as a rotary vane vacuum pump, can be equipped with a protection device to avoid a pressure rise and/or a backflow of oil towards the vacuum chamber when the pump is switched off. In this way, the vacuum chamber can be completely isolated from the positive displacement vacuum pump.

In the case of a vacuum pumping system with a plurality of positive displacement pumps working in parallel, each positive displacement pump is equipped with its own protection device, such as an anti-backflow valve, which prevents backflow towards the vacuum chamber, thereby suppressing the risk of contamination of the vacuum chamber.

However, when two or more positive displacement vacuum pumps are connected in parallel to the same vacuum chamber, the anti-backflow valves fitted on each individual pump may fail under some specific operating conditions, exposing the vacuum chamber to contamination.

In order to avoid the risk of contamination in all cases (during normal operating conditions and error conditions), vacuum pumping with external systems or devices may be provided. For example, an isolation valve may be provided for each positive displacement pump.

However, this solution is not attractive as it increases the number of components and complexity of the vacuum pumping system and involves additional costs.

In previous analytical instruments (mass spectrometers) that relied on vacuum pumping systems and were run by the present applicant, a plurality of vacuum pumps were in common fluid communication with the vacuum chamber of the vacuum pumping system, for example through a T-connector in common communication with the vacuum port of the vacuum chamber. It is not known that these systems are contaminated due to a failure of the vacuum pump. Recent development work by the applicant has resulted in the need for vacuum pumps in separate communication with the vacuum chamber, such that the vacuum chamber forms a fluid path between the vacuum pumps. While vacuum pumps operate in a conventional manner, the present inventors have unexpectedly discovered a contamination problem with such systems. Accordingly, the present inventors have recognized a need for a system and method for operating a plurality of vacuum pumps in separate communication with a vacuum chamber that reduces the risk of contaminating the vacuum chamber.

It is a primary object of the present invention to provide a vacuum pumping system in which the risk of contaminating the vacuum chamber is suppressed, while avoiding the introduction of additional external devices or systems.

Another object of the present invention is to provide a method for operating a vacuum pumping system which allows to avoid the risk of contaminating the vacuum chamber without implementing any additional external devices or systems.

These and other objects are achieved by a vacuum pumping system and a method for operating a vacuum pumping system as described in the appended claims.

Disclosure of Invention

The present inventors have found that when two or more vacuum pumps are connected to a vacuum chamber respectively, i.e. each vacuum port connects at least one vacuum pump to the vacuum chamber respectively through a separate vacuum port in fluid communication with the vacuum chamber, the vacuum chamber of the vacuum pumping system may be contaminated. Under certain pump operating conditions, it is possible for one vacuum pump of the vacuum pumping system to cause backflow through the other vacuum pump, thereby drawing contaminated gas into, and thus contaminating, the vacuum chamber.

The vacuum pumping system according to the invention comprises a plurality of positive displacement vacuum pumps working in parallel, i.e. intended to be connected respectively to the same vacuum chamber, and/or to vacuum pumping chambers communicating with each other.

The vacuum pumping system further comprises a management unit controlling all positive displacement vacuum pumps of the vacuum pumping system in a synchronized manner. The operating parameters of the vacuum pumps are adjusted in a synchronized manner to avoid a situation in which one or more vacuum pumps may back-flow into the common vacuum chamber.

More specifically, the management unit is configured to:

-identifying one or more operating parameters related to the risk of contamination of the vacuum pumping system by the positive displacement pump;

-setting a threshold value or threshold state for each of said parameters;

-controlling all positive displacement vacuum pumps of the vacuum pumping system by detecting an identification parameter of each pump and by comparing, for each pump, the current value or state of the identification parameter with a corresponding threshold value or state.

In an embodiment, the management unit may be configured to:

-monitoring one or more operating parameters of each of the vacuum pumps of the parallel vacuum pumping system;

-identifying a condition in which at least one of the pumps is operating at a threshold level from the monitoring, the threshold level being indicative of a risk of or a condition indicative of potential backflow from the or another pump of the vacuum pumping system;

-synchronizing operation of the vacuum pumps of the vacuum pumping system based on the identified state to prevent backflow.

In some aspects, synchronizing operation may include increasing an operating speed of one or more vacuum pumps that are pumping down relative to the other one or more vacuum pumps. In some aspects, synchronizing operation may include reducing an operating speed of one or more vacuum pumps that are overdrawn relative to other one or more vacuum pumps. In some aspects, the one or more operating parameters include a measure of pump speed/frequency.

The management unit is further configured to perform a corrective action in a synchronized manner on a plurality of positive displacement pumps of the vacuum pumping system (preferably all of said positive displacement vacuum pumps) in case the detected value of one or more identification parameters exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

More specifically, the management unit is further configured to switch off the plurality of positive displacement pumps (preferably all of said positive displacement vacuum pumps) of the vacuum pumping system in a synchronized manner in case the detected value of the one or more identification parameters exceeds the corresponding threshold value or the detected state of the one or more identification parameters does not coincide with the corresponding threshold state.

The management unit may be further configured to trigger an alarm in case the detected value of the one or more identification parameters exceeds the corresponding threshold value or the detected state of the one or more identification parameters does not coincide with the corresponding threshold state.

Advantageously, the present invention provides a synchronized management of a plurality of positive displacement vacuum pumps (preferably all of said positive displacement vacuum pumps) of a vacuum pumping system, so that the failure of a single vacuum pump is immediately taken into account by acting not only on the faulty vacuum pump, but also on the other vacuum pumps of the vacuum pumping system, thereby effectively preventing any risk of contamination of the vacuum pumping system itself.

The management unit may control all positive displacement vacuum pumps of the vacuum pumping system simultaneously.

Alternatively, the management unit may control all the positive displacement vacuum pumps of the vacuum pumping system sequentially or according to a predetermined sequence.

The management unit may continuously control the positive displacement vacuum pump of the vacuum pumping system.

Alternatively, the management unit may control the positive displacement vacuum pump of the vacuum pumping system in a discrete manner at predetermined time intervals.

Advantageously, the management unit of the vacuum pumping system according to the invention allows to check the possible risk of contamination of the vacuum pumping system and to perform the necessary corrective actions when required, without requiring any modifications to the construction of the vacuum pumping system, i.e. without requiring any additional components, such as sensors, vacuum gauges, isolation valves, etc.

As is known, while positive displacement vacuum pumps may be connected directly to a vacuum chamber, they are more often used as backing pumps for high vacuum pumps, such as turbo-molecular vacuum pumps.

Accordingly, the vacuum pumping system according to the invention may further comprise one or more high vacuum pumps (e.g. one or more turbomolecular pumps), and the management unit may be configured to control said high vacuum pumps with the aim of increasing their working life.

For example, in the case of a turbomolecular vacuum pump, by examining parameters of the bearings such as power, frequency and temperature, failure of the turbomolecular vacuum pump can be predicted.

Furthermore, in the event of a failure of a positive displacement vacuum pump operating as a backing pump of a turbomolecular vacuum pump, the turbomolecular vacuum pump itself will operate in a critical state. In this case, by checking the parameters of all the vacuum pumps of the vacuum pumping system in a synchronized manner, the management unit will be able to immediately shut down the turbomolecular vacuum pumps, thereby avoiding damage and increasing the working life.

In some embodiments of the vacuum pumping system, the management unit may be operative to initiate a startup sequence that sequentially verifies operation of the vacuum pumps in a synchronized manner to confirm that the identified operating parameters are maintained within an expected threshold or band prior to increasing the pumping speed to cause an operating vacuum in the vacuum chambers of the vacuum pumping system. In some aspects, the vacuum pumping system may include a plurality of sets of one or more vacuum pumps, each of the plurality of sets of one or more vacuum pumps being in respective communication with the vacuum chamber of the vacuum pumping system. The anti-suck back valve may separate each of the set of one or more vacuum pumps from the vacuum chamber. In operation, the management unit may operate to activate one or more pumps of the first group to operate at a low start-up level while one or more pumps of the other group remain inactive. The inoperative pump does not apply suction to its respective return valve, which causes the return valve to remain closed, thereby preventing backflow. The management unit monitors one or more operating parameters of the first set of pumps to identify that the first set of pumps are operating as expected. After confirming the expected operation of the first group of pumps, the management unit activates one or more pumps of the next group. The operating parameters of the next set of pumps are set to synchronize operation of the next set of pumps with a previous activation of a set of pumps to avoid a backflow condition when the backflow valve is open and the first set of pumps is in communication with the second set of pumps. In some aspects, other sets of pumps may be similarly activated, monitored, and synchronized to avoid a reflux condition. In some embodiments of the vacuum pumping system, the management unit may be operative to monitor operation of the vacuum pump to confirm that it is operating in a synchronous manner by monitoring operating parameters of the pump to confirm that it is maintained within a desired threshold or band for a given operating condition. In some aspects, the vacuum pumping system may include a plurality of sets of one or more vacuum pumps, each of the plurality of sets of one or more vacuum pumps being in respective communication with the vacuum chamber of the vacuum pumping system. The anti-suck back valve may separate each of the set of one or more vacuum pumps from the vacuum chamber. In operation, the management unit may operate to monitor one or more operating parameters of the pump to identify that it is operating as intended. When the management unit detects that the pump is operating outside of the expected state, for example by detecting that an operating parameter of the pump meets or deviates from an expected threshold, the management unit may operate to synchronize the operation of the pump to avoid operating conditions of other pumps that would result in backflow through one or more pumps of the system.

Accordingly, a method for operating a vacuum pumping system comprising a plurality of positive displacement vacuum pumps according to the present invention comprises the steps of:

-identifying one or more operating parameters related to contamination of the vacuum pumping system by the positive displacement pump;

-setting a threshold value or threshold state for each of said parameters;

-detecting an identification parameter for each positive displacement pump;

-for each positive displacement pump, comparing the detected value or state of the identification parameter with a corresponding threshold value or state.

The method further comprises the step of performing a corrective action in a synchronized manner on a plurality of positive displacement pumps of the vacuum pumping system, preferably all of said positive displacement vacuum pumps, in case the detected value of one or more identification parameters exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

More particularly, the method preferably comprises the step of shutting down a plurality of positive displacement pumps (preferably all of said positive displacement vacuum pumps) of the vacuum pumping system in a synchronized manner in case the detected value of one or more identification parameters exceeds a corresponding threshold value or the detected state of one or more identification parameters does not coincide with a corresponding threshold state.

Furthermore, the method may comprise the step of triggering an alarm in case the detected value of one or more identification parameters exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

The detecting and comparing steps may be performed simultaneously for all positive displacement pumps of the vacuum pumping system.

Alternatively, the detecting and comparing steps may be performed sequentially or according to a predetermined sequence on a positive displacement pump of the vacuum pumping system.

The detection and comparison steps may be performed in a continuous manner.

Alternatively, the detecting and comparing steps may be performed in a discrete manner, at predetermined time intervals.

In some embodiments, a vacuum pumping system is provided. The vacuum pumping system may include at least one vacuum chamber in communication with each other and a plurality of vacuum pumps each respectively connected to the at least one vacuum chamber. The management unit may be configured to control operation of the plurality of vacuum pumps and monitor one or more operating parameters of the plurality of vacuum pumps. Based on the monitoring, the management unit may identify a mismatch in expected pumping between one or more of the plurality of vacuum pumps based on one or more operating parameters. In some aspects, the at least one interconnected vacuum chamber of the vacuum pumping system comprises a plurality of interconnected vacuum chambers, and wherein one of the plurality of vacuum pumps is in separate communication with a first of the plurality of vacuum chambers and another of the plurality of vacuum pumps is in separate communication with another of the plurality of vacuum chambers. In some aspects, at least one of the vacuum chambers is in communication with the atmosphere. In some aspects, the management unit may be further operable to activate the plurality of vacuum pumps by: activating a first vacuum pump of the plurality of vacuum pumps, monitoring one or more operating parameters of the first vacuum pump, confirming, in accordance with the monitoring, that the first vacuum pump is providing the desired pumping, such as by operating within a desired pump speed range, and activating, based on the confirmation, a second vacuum pump (of the plurality of vacuum pumps); one or more operating parameters of the first vacuum pump and the second vacuum pump are monitored while synchronizing operation of the first vacuum pump and the second vacuum pump to match an expected pump speed of the first vacuum pump and an expected pump speed of the second vacuum pump to prevent backflow from one of the plurality of vacuum pumps into the at least one interconnected vacuum chamber.

In embodiments of the above-described vacuum pumping system or method, in some embodiments, the one or more operating parameters may be selected from the group consisting of: pump speed or frequency, power, current, voltage, and temperature of pump components.

Drawings

Some preferred embodiments of the invention, given by way of non-limiting example, will be described below with reference to the accompanying drawings, in which:

figure 1 is a longitudinal cross-sectional view of a portion of a vacuum pump of the prior art;

figure 2 is a cross-sectional view of a portion of a vacuum pump similar to the prior art of figure 1;

figures 3 a-3 c are schematic views of possible configurations of the vacuum pumping system according to the present invention;

figure 4 is a flow chart illustrating the operation of the management unit of the vacuum pumping system according to the present invention in a first operating condition;

figure 5 is a flow chart illustrating the operation of the management unit of the vacuum pumping system according to the present invention in a second operating condition;

figure 6 is a flow chart illustrating the operation of the management unit of the vacuum pumping system according to the present invention in a third operating condition;

figure 7 is a flow chart illustrating the operation of the management unit of the vacuum pumping system according to a variant of the present invention in a third operating condition;

FIG. 8 is a schematic diagram of an embodiment of a vacuum pumping system according to aspects of the present invention in an example mass spectrometer system;

FIG. 9 is a block diagram illustrating a computer system upon which embodiments of the present teachings can be implemented in accordance with various aspects of applicants' teachings.

Detailed Description

The invention may be advantageously applied to vacuum pumping systems comprising two or more positive displacement pumps working in parallel and/or connected to interconnected vacuum chambers.

Fig. 3 a-3 c illustrate some illustrative, non-limiting examples of configurations of such vacuum pumping systems 100.

However, it will be appreciated that the invention may be applied to vacuum pumping systems comprising a plurality of positive displacement vacuum pumps of any type and configuration and possibly also comprising one or more high vacuum pumps of any type and configuration.

Fig. 3a shows a first exemplary embodiment of the vacuum pumping system 100 of the present invention, wherein the two positive displacement vacuum pumps 20, 30 are each connected to the same vacuum chamber 60, i.e. they work in parallel, but are connected to the vacuum chamber 60 through separate vacuum ports. In fig. 3a, the vacuum chamber 60 is in fluid communication between the vacuum pumps 20, 30.

Fig. 3b shows a second exemplary embodiment of the vacuum pumping system 100 of the present invention, wherein the first positive displacement vacuum pump 20 is connected to the first vacuum chamber 60 and the second positive displacement vacuum pump 30 is connected to the second vacuum chamber 70, the vacuum chambers 60, 70 being in fluid communication with each other. Similar to fig. 3a, the vacuum chambers 60, 70 form a fluid communication between the vacuum pumps 20, 30.

Fig. 3c shows a third exemplary embodiment of the vacuum pumping system 100 of the invention, wherein the first positive displacement vacuum pump 20 is connected to the first vacuum chamber 60 and the second positive displacement vacuum pump 30 operates as a backing pump for the high vacuum pump 40 (e.g. a turbo-molecular vacuum pump), which in turn is connected to the second vacuum chamber 70, the vacuum chambers 60, 70 being in fluid communication with each other. Similar to fig. 3a, the vacuum chambers 60, 70 and the high vacuum pump 40 form a fluid communication between the vacuum pumps 20, 30.

In the exemplary vacuum pumping system of fig. 3 a-3 b, the first and second positive displacement pumps may be grease lubricated pumps, such as first and second rotary vane vacuum pumps, having the general structure shown in fig. 1 and 2.

However, positive displacement vacuum pumps having different structures and operations may be selected as the first and second positive displacement pumps in the vacuum pumping system.

More particularly, different types of vacuum pumps may be selected as the first and second positive displacement pumps in the vacuum pumping system: for example, one of the positive displacement pumps may be a grease lubrication type pump, such as a rotary vane vacuum pump, having an overall structure as shown in fig. 1 and 2, and the other may be a positive displacement pump having a different structure.

It will be apparent to a person skilled in the art that in all of the illustrated embodiments, failure of one of the first rotary vacuum pump 20 and the second rotary vacuum pump 30 will result in a risk of contamination of the vacuum pumping system.

In all the illustrated configurations, for example, if the first rotary vane vacuum pump 20 is stopped due to a failure and the second rotary vane vacuum pump 30 is turned on when starting the vacuum pumping system, oil vapor at the inlet of the first rotary vane vacuum pump 20 will be pumped by the second rotary vane vacuum pump 30 and drawn into the vacuum chamber 60 or vacuum chambers 60, 70, thus contaminating the vacuum pumping system.

In some arrangements, an anti-suck back valve may be introduced between the vacuum pump 20, 30 and the vacuum chamber 60, 70. When the vacuum pumps 20, 30 are not operating, the anti-suck back valves can be closed to prevent backflow into the vacuum chambers 60, 70. Upon actuation of the vacuum pumps 20, 30, the anti-suck back valve opens under the vacuum generated by the vacuum pumps 20, 30. The inventors have determined that in some operating conditions, the anti-suck back valve may open upon actuation of its associated pump 20, 30, but under certain flow conditions in the vacuum chamber 60, 70 it may cause backflow from the pump 20, 30 to the vacuum chamber 60, 70. These operating states may typically exist during uncoordinated start-up of the vacuum pumps 30, 40, defective operation of the vacuum pumps 30, 40 or uncoordinated shut-down of the vacuum pumps 30, 40. Backflow from the pumps 20, 30 to the vacuum chambers 60, 70 may result in contamination and inaccurate measurements of analytical instruments operating within the vacuum system 100.

In some embodiments, one of the vacuum chambers 60, 70 of the vacuum system 100 may be in communication with the atmosphere, for example, through an aperture. In these embodiments, the vacuum chambers 60, 70 are maintained at different operating pressures during operation, and fluid is continuously drawn through the apertures by operation of the vacuum pumps 20, 30. When working on these embodiments, it has been found that unsynchronized operation of the vacuum pumps 20, 30 generates unexpected flow conditions that can result in backflow from one or more of the vacuum pumps 20, 30 into the vacuum chambers 60, 70.

In all of the exemplary embodiments shown and described above in fig. 3 a-3 c, the vacuum pumping system 100 further comprises a management unit 90.

The management unit 90 is configured to control both rotary vane vacuum pumps 20, 30 in a synchronized manner. By controlling the vacuum pumps 20, 30 in a synchronized manner, a backflow condition from at least one of the vacuum pumps 20, 30 into the vacuum chambers 60, 70 is avoided.

In detail, the management unit 90 is intended to check whether a possible risk of contamination occurs and, upon determining the occurrence of a risk, to carry out the necessary corrective action to avoid such contamination.

For this purpose, the management unit 90:

-identifying one or more operating parameters related to contamination of the vacuum pumping system by the positive displacement pump;

-setting a threshold value or threshold state for each of said parameters;

-detecting an identification parameter of each positive displacement pump 20, 30;

-for each positive displacement pump 20, 30, comparing the current value or state of the identification parameter with a corresponding threshold value or state;

in the event that the detected values of one or more identification parameters of one or more of the positive displacement pumps exceed the corresponding threshold values or the detected state of one or more identification parameters does not coincide with the corresponding threshold state, a corrective action is performed in a synchronized manner on both positive displacement pumps 20, 30.

Preferably, the management unit 90 switches off both positive displacement pumps 20, 30 in a synchronized manner in case the detected values of one or more identification parameters of one or more of the positive displacement pumps exceed the corresponding threshold values or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

Preferably, the management unit 90 also triggers an alarm in case the detected value of one or more identification parameters of one or more positive displacement pumps exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

By acting on the positive displacement pumps of the vacuum pumping system, and preferably on all the positive displacement pumps of the vacuum pumping system, in a synchronized manner, the management unit 90 of the vacuum pumping system according to the present invention allows to effectively prevent any risk of contamination due to the positive displacement vacuum pump running after the failure of another positive displacement pump of the vacuum pumping system, or to slow down and deactivate the positive displacement vacuum pump in a synchronized manner with the slowing down and deactivation of a malfunctioning pump or a pump running outside its expected operating parameters.

And this effect can be achieved by the present invention without introducing any additional safety features.

Referring to the exemplary configuration of fig. 3c, the management unit 90 may also be configured to control the turbomolecular vacuum pump 40.

More specifically, in the event that the detected value of one or more identification parameters of one or more of the positive displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state, the management unit 90 may be further configured to perform a corrective action on the turbomolecular vacuum pump 40.

For example, the management unit 90 may be further configured to switch off the turbo molecular vacuum pump 40 in case the detected value of one or more identification parameters of one or more of the positive displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

Fig. 4-7 are flow charts illustrating, by way of non-limiting example, the operation of the management unit 90 of the vacuum pumping system according to the invention in a possible operative state of the vacuum pumping system itself.

In fig. 4-7, the operation of the management unit of the vacuum pumping system with the configuration according to fig. 3a is shown. However, similar flow diagrams may also be drawn for vacuum pumping systems having different configurations, such as those shown in fig. 3b and 3 c.

In the flow charts of fig. 4-6, the pump frequency is mainly used as a parameter for controlling the operation of the positive displacement vacuum pumps 20, 30 of the vacuum pumping system. The operating frequency of the pumps 20, 30 is selected to correspond to the desired pressure within the vacuum chambers 60, 70. When the system comprises a plurality of vacuum pumps 20, 30 in separate communication with the vacuum chambers 60, 70, then the pressure of each of the vacuum chambers 60, 70 is dependent on the vacuum pump 20, 30 each operating at the operating frequency selected for that pump 20, 30. Thus, monitoring the pump frequency is a useful parameter for synchronizing the pumps 20, 30 to achieve a desired pressure range in each of the vacuum chambers 60, 70.

It is clear, however, that this choice should not be understood as limiting: positive displacement vacuum pumps are complex devices in which different operating parameters are closely related, such as the power absorbed by the pump, current, voltage, temperature of pump components, etc.; any of these parameters and others may be used as the control parameter. In some embodiments, the operating parameters may include a measure of the environment of the vacuum pumping system, such as the pressure of each of the vacuum chambers 60, 70, the flow rate through the connection between the pump 20, 30 and the vacuum chamber 60, 70, or some combination of such factors. Furthermore, in more complex control algorithms, several parameters may be used to check the operation of the positive displacement vacuum pump.

Fig. 4 shows, by way of non-limiting example, the operation of the management unit 90 in a first operating state of the vacuum pumping system, which corresponds to a normal operating state of the vacuum pumping system 100.

In this operational state, the rotary vane vacuum pumps 20, 30 are operated at a nominal frequency, the pressure in the vacuum chambers 60, 70 matches the expected operating pressure, and flows into each of the vacuum pumps 20, 30.

The management unit 90 identifies two parameters related to the possible risk of contamination of the vacuum pumping system:

-a first parameter: failure of the rotary vane vacuum pump;

-a second parameter: pump frequency of a rotary vane vacuum pump.

The first parameter may assume two states, yes or no. The management unit 90 sets "no" to a state where there is no risk of contamination, and sets "yes" to a state where the risk of contamination occurs.

The second parameter may assume a range of values, while the management unit 90 sets a threshold minimum below which the risk of contamination arises.

In this first operable state, therefore, the management unit 90 operates as follows:

the rotary vane vacuum pump 20, 30 is operated at a nominal frequency (step 101);

the management unit 90 checks the actual frequency of the pumps 20, 30 and compares the actual frequency with the nominal frequency for each pump (step 103);

-if the actual frequency is equal to the nominal frequency, no corrective action is carried out and a new control cycle is started;

if not, the management unit checks for each pump whether the pump is de-rated (step 105);

if any of the pumps is de-rating, the management unit 90 further detects the pump frequency of each pump 20, 30 and compares the detected frequency with a minimum threshold (step 107);

if the detected frequencies for both pumps 20, 30 are above a minimum threshold, the management unit 90 triggers an alarm indicating that the pump frequency of one of the pumps is different from the nominal frequency (step 109);

if the frequency detected for one of the pumps 20, 30 is lower than a minimum threshold, the management unit 90 detects a dangerous situation and triggers a synchronous shut-down procedure of the two pumps 20, 30 (step 111);

if there is no pump derate, the management unit 90 further checks if one of the pumps fails (step 113);

if either of the pumps fails, the management unit 90 detects a dangerous situation and triggers a synchronized shut-down procedure of the two pumps 20, 30 (step 115);

-if none of the pumps fails, no corrective action is applied and a new control cycle is started.

The above control cycle may be performed continuously or at predetermined time intervals.

Fig. 5 shows, by way of non-limiting example, the operation of the management unit 90 in a second operating state of the vacuum pumping system, which corresponds to the discharge phase when shut down.

In this operational state, the rotary vane vacuum pump 20, 30 will normally be stopped and the anti-suck back valve (ASBV) will be closed. This ensures that the vacuum system will not be contaminated unless the ASBV fails. Thus, the risk of contamination during the discharge phase is relatively low.

In this state, the management unit 90 identifies a single parameter related to the possible contamination risk of the vacuum pumping system, i.e. the rotary vacuum pump is still running.

The parameter may assume two states, yes or no. The management unit 90 sets "no" to a state where there is no risk of contamination, and sets "yes" to a state where the risk of contamination occurs.

In this second operational state, the management unit 90 therefore operates as follows:

-the discharge phase is open (step 201);

simultaneously shutting down the rotary vane vacuum pumps 20, 30 (step 203);

the management unit 90 checks for each pump whether the pump has stopped (step 205);

if both pumps 20, 30 have stopped, the management unit does not perform any corrective action and the vacuum pumping system is placed in air;

if not, the management unit 90 triggers an alarm to indicate to the operator that one or both of the vacuum pumps 20, 30 must be manually switched off.

Fig. 6 is a flow chart illustrating the operation of the management unit 90 in a third operational state of the vacuum pumping system, which corresponds to the start-up of the vacuum pumping system.

In view of the risk of contamination of the vacuum pumping system, the start-up phase is the most critical phase, since the ASBV of the pumps 20, 30 is open at atmospheric pressure.

If during the start-up phase one of the pumps 20, 30 achieves the target frequency while the other pump 30, 20 is stopped for any reason, the operating pump is able to draw oil vapor from the other pump 20 through the vacuum chamber 60. The net effect is that the vacuum pumping system becomes contaminated.

During the start-up phase, the pump starts at its minimum frequency and gradually increases to the nominal frequency. During the gradual increase in frequency, the difference in pumping speed of the pumps connected to the same vacuum chamber must be kept to a minimum. In embodiments employing different size or type pumps, the pumping speed of each pump may be different in synchronous operation, however, its effective pumping on vacuum is matched to avoid one pump drawing back flow through another. The pumping speed or effective pumping of the pump may be reflected by one or more operating parameters including, for example, pump frequency, power draw, etc.

In this state, the management unit 90 identifies two parameters related to the possible risk of contamination of the vacuum pumping system:

-a first parameter: failure of a rotary vane vacuum pump;

-a second parameter: the difference between the pump frequency of the first rotary vane vacuum pump 20 and the pump frequency of the second rotary vane vacuum pump 30 at a certain delay after the rotary vane vacuum pumps have been turned on.

The management unit 90 sets a maximum threshold value for the difference in pump frequency.

In this third operational state, the management unit 90 therefore operates as follows:

-start-up phase on (step 301);

-bringing the frequency of the rotary vane vacuum pump 20, 30 to a first check value (step 303);

the management unit checks whether the two pumps have reached a first check value after a first predetermined time interval, i.e. whether the difference between the frequencies of the pumps is within a set threshold (step 305);

if not, the management unit checks if any of the pumps is failed (step 307); if so, the management unit turns off both pumps 20, 30 (step 309); if not, continuing to gradually increase the frequency of the pump, and performing a new check;

if so, the gradual increase in frequency continues and both pumps are brought to the second check value (step 311);

the management unit checks whether the two pumps have reached the second check value after a third predetermined time interval, i.e. whether the difference between the frequencies of the pumps is within a set threshold (step 313);

if not, the management unit checks if any of the pumps is failed (step 315) and further checks if the frequency of any of the pumps has fallen below a first check value (step 317); if one of these conditions is met, the management unit shuts down both pumps 20, 30 (step 309); if these conditions are not met, the frequency of the pump is continued to be gradually increased and a new check is made;

if so, the frequency continues to increase gradually, bringing both pumps to the final check value corresponding to the nominal frequency (step 319);

the management unit checks whether the two pumps have reached the final check value after a fourth predetermined time interval, i.e. whether the difference between the frequencies of the pumps is within a set threshold (step 321);

-if not, the management unit checks if any of the pumps has failed (step 323) and further checks if the frequency of any of the pumps has fallen below a second check value (step 325); if one of these conditions is satisfied, the management unit shuts down both pumps 20, 30 (step 327); if the states are not satisfied, the frequency of the pump is gradually increased continuously, and a new check is carried out;

if so, normal operation of the vacuum pumping system is achieved (step 329).

Fig. 7 is a flow chart showing the operation of the management unit 90 in the same operating conditions as fig. 6, but applied to a vacuum pumping system comprising two rotary vane vacuum pumps of significantly different dimensions.

In this case, only the smaller pump is started first, while the larger pump is started at a later stage.

The flow chart of fig. 7 therefore differs from the flow chart of fig. 6 in that it initially comprises the following steps:

bringing the frequency of the first rotary vane vacuum pump 20 to a first check value (step 331);

the management unit checks whether the first pump has reached a first check value after a first predetermined time interval (step 333);

-if no, shutting down the pump (step 335);

if so, bringing the frequency of the second rotary vane vacuum pump 30 to the first check value (step 337).

Then, the operation of the management unit is the same as that described with reference to fig. 6.

It will be obvious to those skilled in the art that the foregoing description is given by way of non-limiting example only, and that many variations and modifications are possible without departing from the scope of the invention as defined in the appended claims.

For example, it is clear that many other operating conditions of the vacuum pumping system and corresponding parameters related to possible contamination risks may be considered.

Furthermore, although reference is made to a rotary vane vacuum pump in the description of the preferred embodiment of the invention, it is clear that the invention can be applied to vacuum pumping systems having a plurality of positive displacement vacuum pumps.

For example, the present invention may be applied to a vacuum pumping system having a plurality of scroll vacuum pumps.

In this case, the risk of contamination will be related to the dust that may be present at the inlet of the scroll vacuum pump: if one of the scroll vacuum pumps is stopped due to a failure, another vacuum pump of the vacuum pumping system may suck dust at the inlet of the scroll vacuum pump that has been stopped; as a result, the sucked dust passes through the vacuum chamber to which the vacuum pump is connected, and the final effect is that the vacuum pumping system is contaminated.

Referring now to FIG. 8, an example mass spectrometer system 800 implementing a vacuum pumping system according to various aspects of the present teachings is schematically depicted. As shown in fig. 8, the example mass spectrometer system 800 generally includes an ion source 802 for generating ions within an ionization chamber 850, which are then transported in the general direction indicated by the arrows through various differentially pumped vacuum chambers 860, 870 and 880a, 880b housing one or more ion guides (e.g., ion guide 806, ion guide 810, ion guide 814, mass spectrometer 818) for processing, mass analysis, and/or detection of the ions. The administration unit 890 is operably connected to a vacuum pumping system comprising one or more positive displacement vacuum pumps 820, 830 and one or more turbomolecular pumps 840a, 840b, the administration unit 890 being configured to maintain the various chambers at various operating pressures as discussed further herein.

The ion source 802 may be any known or hereafter developed ion source for generating ions and modified in accordance with the present teachings. Non-limiting examples of ion sources suitable for use in the present teachings include Atmospheric Pressure Chemical Ionization (APCI) sources, electrospray ionization (ESI) sources, continuous ion sources, pulsed ion sources, Inductively Coupled Plasma (ICP) ion sources, matrix assisted laser desorption/ionization (MALDI) ion sources, glow discharge ion sources, electron impact ion sources, chemical ionization sources, or photoionization ion sources, among others. Additionally, as shown in fig. 1, the system 800 may include a sample source configured to provide a sample to an ion source 802. The sample source may be any suitable sample inlet system known in the art. By way of example, the ion source 802 may be configured to receive fluid samples from various sample sources, including reservoirs containing fluid samples to be delivered to the sample source (e.g., pumped), Liquid Chromatography (LC) columns, capillary electrophoresis devices, and ejection of samples into a carrier liquid. In the example shown in fig. 8, ion source 802 comprises an electrospray electrode, which may comprise a capillary tube fluidly coupled to a sample source (e.g., via one or more conduits, channels, tubes, capillaries, etc.) and terminating in an outlet end that extends at least partially into ionization chamber 850 to discharge a liquid sample therein.

The analyte of interest contained within the sample expelled from ion source 802 can be ionized within ionization chamber 850, ionization chamber 850 being separated from first vacuum chamber 860 by shutter plate 804a and aperture plate 804b, shutter plate 804a and aperture plate 804b having apertures (e.g., holes 861) that provide fluid communication between ionization chamber 850 and first vacuum chamber 860. In this embodiment, the apertures in the shutter plate 804a and the aperture plate 804b are large enough to allow incoming ions to enter the first vacuum chamber 860. By way of example, the aperture (e.g., aperture 861) may be substantially circular with a diameter in the range of about 0.6mm to about 10 mm.

Although not shown in the schematic diagram of fig. 8, system 800 may include various other components. For example, the system 800 may include a shielding gas supply (not shown) that provides a flow of shielding gas (e.g., N) adjacent to the shielding plate 804₂) To help reduce contamination in the high vacuum downstream vacuum chamber (e.g., by deagglomerating and expelling large neutral particles). In some aspects, a portion of the shield gas can flow out of shield plate apertures 861 into ionization chamber 850, thereby preventing droplets and/or neutral molecules from entering through shield plate apertures 861.

In various aspects, ionization chamber 850 may be maintained at a pressure P₀Pressure P₀May be at or about atmospheric pressure (e.g., about 760 torr). However, in some embodiments, ionization chamber 850 may be evacuated to a pressure below atmospheric pressure, e.g., via a pump (not shown) coupled to ionization chamber 850.

Initially, ions generated by the ion source 802 may be serially transported through the upstream ion guides 806, 810, 814 disposed in the differentially pumped intermediate vacuum chambers 860, 870, 880a in the direction indicated by the arrows in fig. 8 to generate a narrow and highly focused ion beam (e.g., along the central longitudinal axis of the system 800) for further m/z-based analysis within the high vacuum chamber 880b in which the mass spectrometer 818 is disposed.

The upstream ion guides 806, 810, 814 can have a variety of different configurations. As a non-limiting example, first ion guide 806 may comprise a collection of rods arranged in a twelve-pole configuration so as to provide a passageway for ions to pass through ion guide 806. An example of such an ion guide is described in U.S. patent No. 10,475,633, the teachings of which are incorporated herein by reference in their entirety. More generally, the first ion guide 806 may comprise any number of rods, for example, a plurality of rods maintained in a quadrupole, hexapole, octapole, or dodecapole configuration, or may be formed using a series of stacked rings such that application of DC and/or RF voltages to one or more of the rods or rings, in combination with gas dynamics, may allow the ion guide 806 to collect ions received through the apertures 861 as the ion guide 806 passes through the ion guide 806 for transmission to downstream elements, in a manner known in the art.

As further described herein, operation of the vacuum pumping system may maintain the pressure in each chamber within a desired range. For example, the first positive displacement vacuum pump 820 may be in communication with the first chamber 860 via, for example, an opening or port, so as to apply a negative pressure to the chamber 860 to pressurize (P) in the first vacuum chamber 860₁) Is maintained within a range between about 1 torr and about 100 torr, although other pressures may be used for this or other purposes. In some aspects, the chamber 860 may be maintained in a range of about 1 torr to about 15 torr, for example, in a range of about 4 torr to about 8 torr.

An aperture 871 provided in an ion lens 808 (also referred to herein as IQ00) located downstream of the first ion guide 806 allows ions to pass from the first vacuum chamber 860 into a second downstream vacuum chamber 870 in which another ion guide 810 is located in the second downstream vacuum chamber 870. It will be appreciated that vacuum chambers 860, 870 are thus in fluid communication through aperture 871 such that gas may flow therebetween, depending, for example, on the pressure differential therebetween. In this embodiment, aperture 871 in ion lens 808 is large enough to allow ions transmitted from first ion guide 806 to enter second vacuum chamber 870.

Ion guide 810 may have the same or different configuration as ion guide 808, but may generally be configured to focus ions received through aperture 871 to a downstream element, for example, using a combination of electric fields and gas dynamics. As described above, a power supply (not shown) may apply RF and/or DC voltages to the rods of the ion guide 810 to radially confine and focus ions as they pass.

As shown in fig. 8, the vacuum pumping system may further include at least a second positive displacement vacuum pump 830, which may be coupled to the chamber 870 (e.g., via an opening or port) so as to be capable of applying a negative pressure to the chamber 870 to apply a pressure (P) in the second vacuum chamber 870₂) Maintained within the desired range. In some embodiments, the pressure within chamber 870 is generally maintained at specific chamber (P)₁) A low pressure of (2). By way of non-limiting example, the pressure (P) in the second vacuum chamber₂) May be maintained in a range between about 500 millitorr and about 5 torr, although other pressures may be used for this or other purposes.

An ion lens 812 (also referred to as IQ0) separates the second vacuum chamber 870 from a third vacuum chamber 880a, in which third vacuum chamber 880a further ion guide 814 may be arranged. An aperture 881 disposed within the ion lens 812 allows the ions transmitted from the ion guide 810 to pass into the third vacuum chamber 880 a. It should be understood that vacuum chambers 870, 880a are thus in fluid communication through aperture 881 such that gas may flow therebetween, depending, for example, on pressure differential. In this embodiment, the aperture 881 in the ion lens 812 is large enough to allow the ions transmitted from the second ion guide 810 to enter the third vacuum chamber 880 a.

Ion guide 814 may have the same or a different configuration as ion guide 810, but may generally be configured to further concentrate ions received through aperture 881 as they are transmitted through the intermediate pressure region before the ions are transmitted through aperture 891 (also referred to herein as "IQ 1") in ion lens 816 to mass spectrometer 818. In some embodiments, ion guide 814 (also referred to herein as "Q0") can be an RF ion guide and can comprise a quadrupole rod set. As described above, a power supply (not shown) may apply RF to the rods of ion guide 814 to radially confine and focus ions as they pass through.

As shown in fig. 8, the vacuum pumping system can further comprise at least a first high vacuum pump 840a for maintaining vacuum chamber 880a housing ion guide Q0 at vacuum chamber 870 (e.g., at P₂At) and a vacuum chamber 880b (e.g.,at P₄P) of the intermediate pressure (P) between₃)。

Vacuum pump 840a may be any pump known in the art, such as a turbomolecular pump, which is generally capable of maintaining chamber 880a at a pressure of at least less than about 100 mtorr. In some embodiments, the third vacuum chamber 880a may be maintained at a pressure of between about 3 to 15 mtorr, although other pressures may be used for this or other purposes. While the positive displacement pumps 820, 830 may not be able to individually maintain such a low pressure, the second positive displacement pump 830 may be coupled (e.g., in series) to the pump 840a to act as a backing pump as shown in fig. 8, to help maintain the reduced pressure of the third vacuum chamber 880 a.

Ions are transported from the ion guide 814 into a vacuum chamber 880b housing a mass spectrometer 818, the mass spectrometer 818 typically operating at very low pressure (high vacuum) to reduce the chance of ions colliding with other molecules (e.g., gas molecules) within the one or more mass analyzers to achieve characterization of the ions according to their mass-to-charge ratios (m/z). By way of non-limiting example, in one embodiment, the mass spectrometer 818 may include a detector and two quadrupole mass analyzers (e.g., Q1, Q3) with a collision cell (e.g., Q2) located therebetween. It will be apparent to those skilled in the art that the mass spectrometer 818 employed may take the form of a quadrupole mass spectrometer, a triple quadrupole mass spectrometer, a time-of-flight mass spectrometer, an FT-ICR mass spectrometer or an orbitrap mass spectrometer, all of which are non-limiting examples.

As shown in FIG. 8, the vacuum pumping system can further comprise a second high vacuum pump 840b for maintaining a vacuum chamber 880b housing mass spectrometer 818 at 1 × 10^-4Pressure (P) of Torr or less₄) (e.g., about 5X 10^-5Torr), other pressures may be used for this or other purposes. As shown, a second positive displacement pump 830 may be coupled (e.g., in series) to a pump 840b to act as a backing pump to help pump the pressure (P)₄) Maintained within the desired range. That is, in some embodiments, the second positive displacement pump 830 may be used as a backing pump for two turbomolecular pumps 840a, 840b operating in parallel to maintain the two chambers 880a, 840b at a pressure differential.

It should be understood that not only are adjacent vacuum chambers (e.g., chambers 870, 880a) fluidly coupled by an aperture (e.g., aperture 881), but that each vacuum chamber in the example system 800 is indirectly coupled to each other. In this manner, from the relative pressures between the various chambers, it will be apparent from the present teachings that even if not directly coupled to one vacuum chamber, operation (or failure) of one pump (e.g., pump 820) can affect the pressure in that vacuum chamber and the flow of gas into or out of the vacuum chamber. By way of non-limiting example, if the two pumps 420 and 430 are shut off in an uncoordinated manner, airflow may occur between the downstream chambers due to the pressure differential between each chamber. However, as discussed further herein (e.g., with reference to fig. 3-7), the synchronous control of the parallel pumps 820, 830 may effectively prevent contamination of the system 800 due to backflow of one or more of the pumps 820, 830 from operating in coordination. This contamination results in increased expense of the mass spectrometry system because it requires higher cleaning costs and instrument downtime. Furthermore, the management unit 890 may also be configured to perform corrective actions on the turbo-molecular vacuum pumps 840a, b in case of erroneous or unsynchronized operation of the positive displacement vacuum pumps 820, 830. For example, the management unit 890 may be further configured to switch off the turbo molecular vacuum pumps 840a, 840b in case the detected value of one or more identification parameters of one or more of the positive displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identification parameters does not coincide with the corresponding threshold state.

FIG. 9 is a block diagram illustrating a computer system 900 upon which embodiments of the present teachings can be implemented to prevent backflow conditions from at least one of the pumps 820, 830 into the vacuum chambers 860, 870 of FIG. 8. Computer system 900 includes a bus 922 or other communication mechanism for communicating information, and a processor 920 coupled with bus 922 for processing information. Computer system 900 also includes a memory 924, which may be a Random Access Memory (RAM) or other dynamic storage device, coupled to bus 922 for storing instructions to be executed by processor 920. Memory 924 may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 920. Computer system 900 also includes a Read Only Memory (ROM)926 or other static storage device coupled to bus 922 for storing static information and instructions for processor 920. A storage device 928, such as a magnetic disk or optical disk, is provided and coupled to bus 9 for storing information and instructions.

Computer system 900 may be coupled via bus 922 to a display 930, such as a Cathode Ray Tube (CRT) or Liquid Crystal Display (LCD), for displaying information to a computer user. An input device 932, including alphanumeric and other keys, is coupled to bus 922 for communicating information and command selections to processor 920. Another type of user input device is cursor control 934, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor 920 and for controlling cursor movement on display 930. The input device typically has two degrees of freedom in two axes, a first axis (i.e., x) and a second axis (i.e., y), which allows the device to specify positions in a plane.

Computer system 900 may perform the present teachings. Consistent with certain implementations of the present teachings, results are provided by computer system 900 in response to processor 920 executing one or more sequences of one or more instructions contained in memory 924. Such instructions may be read into memory 924 from another computer-readable medium, such as storage device 928. Execution of the sequences of instructions contained in memory 924 causes processor 920 to perform processes described herein. Alternatively, hard-wired circuitry may be used in place of or in combination with software instructions to implement the present teachings. Thus, implementations of the present teachings are not limited to any specific combination of hardware circuitry and software. For example, according to various embodiments, the present teachings may be performed by a system that includes one or more distinct software modules for synchronizing the operation of the pump to prevent backflow conditions.

In various embodiments, computer system 900 may be connected to one or more other computer systems, such as computer system 900, over a network to form a networked system. The network may comprise a private network or a public network such as the internet. In a networked system, one or more computer systems may store data and provide the data to other computer systems. In a cloud computing scenario, one or more computer systems that store and service data may be referred to as a server or a cloud. The one or more computer systems may include, for example, one or more network servers. Other computer systems that send and receive data to and from a server or cloud may be referred to as clients or cloud devices, for example.

The term "computer-readable medium" as used herein refers to any medium that participates in providing instructions to processor 920 for execution. Such a medium may take many forms, including but not limited to, non-volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device 928. Volatile media includes dynamic memory, such as memory 924. Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus 922.

Common forms of computer-readable media or computer program products include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, Digital Video Disk (DVD), blu-ray disk, any other optical medium, thumb drives, memory cards, a RAM, a PROM, and EPROM, a flash memory, any other memory chip or cartridge, or any other tangible medium from which a computer can read.

Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to processor 920 for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system 900 can receive the data on the telephone line and use an infra-red transmitter to convert the data to an infra-red signal. An infrared detector coupled to bus 922 can receive the data carried in the infrared signal and place the data on bus 922. The bus 922 carries the data to the memory 924, from which the processor 920 retrieves and executes the instructions. The instructions received by memory 924 may optionally be stored on storage device 928 either before or after execution by processor 920.

The description of various embodiments of the present teachings has been presented herein for purposes of illustration and description. It is not exhaustive and does not limit the present teachings to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the present teachings. Additionally, the described embodiments include software, but the present teachings may be implemented as a combination of hardware and software or in hardware alone. The present teachings can be implemented with object-oriented and non-object-oriented programming systems.

30页详细技术资料下载

上一篇：一种医用注射器针头装配设备

下一篇：真空抽气系统

Vacuum pumping system with a plurality of positive displacement vacuum pumps and method for operating a vacuum pumping system

相关技术

网友询问留言