METHODS AND SYSTEMS FOR COOLING A VACUUM PUMP

Abstract

A method comprises: heating a flow of coolant liquid by passing the flow through one or more fluidic tubing lines, channels or conduits that are in thermal contact with a housing of a vacuum pump; apportioning the flow of heated coolant liquid between a bypass fluid tubing line and a channel within a wall of a vacuum chamber; recombining the first and second partial flows of the heated coolant liquid; passing the recombined flow of the coolant liquid through a heat exchanger that cools the coolant liquid; and recirculating the cooled coolant liquid through the one or more fluidic tubing lines, channels or conduits that are in thermal contact with the vacuum pump housing, wherein the apportionment of the flow of the heated coolant liquid is automatically performed under the control of an electronic controller or computer in response to a temperature measurement received by the electronic controller or computer.

Claims

1. A method comprising: heating a flow of a coolant liquid by passing the flow through one or more fluidic tubing lines, channels or conduits that are in thermal contact with a housing of a vacuum pump; apportioning the flow of the heated coolant liquid between a bypass fluid tubing line and a channel within a wall of a vacuum chamber; recombining the first and second partial flows of the heated coolant liquid; passing the recombined flow of the coolant liquid through a heat exchanger that cools the coolant liquid; and recirculating the cooled coolant liquid through the one or more fluidic tubing lines, channels or conduits that are in thermal contact with the vacuum pump housing, wherein the apportionment of the flow of the heated coolant liquid is automatically performed under the control of an electronic controller or computer in response to a temperature measurement received by the electronic controller or computer.

2. A method as recited in claim 1, wherein the vacuum chamber is disposed within a housing of a mass spectrometer, an electron microscope or a chemical vapor deposition apparatus.

3. A method as recited in claim 2, wherein the step of passing the recombined flow of the coolant liquid through the heat exchanger comprises passing the recombined flow of the coolant liquid through a heat exchanger that is disposed outside of the housing of the mass spectrometer, electron microscope or chemical vapor apparatus.

4. A method as recited in claim 2, wherein the step of heating the flow of the coolant liquid comprises passing the flow through one or more fluidic tubing lines, channels or conduits that are in thermal contact with a housing of a vacuum pump that is disposed within the housing of the mass spectrometer, electron microscope or chemical vapor apparatus.

5. A system comprising: a vacuum chamber disposed within a housing and having: a vacuum port; and a wall having a channel therein, said channel comprising a channel inlet and a channel outlet; a vacuum pump having a gas inlet port that is fluidically coupled to the vacuum port; one or more fluidic tubing lines, channels or conduits in thermal contact with a housing of the vacuum pump, wherein an outlet of the one or more fluidic tubing lines, channels or conduits is fluidically coupled to the channel inlet of the channel of the wall of the vacuum chamber; a liquid pump fluidically coupled to an inlet of the one or more fluidic tubing lines, channels or conduits that are in thermal contact with the vacuum pump housing; a heat exchanger comprising: a heat exchanger inlet that is fluidically coupled to the channel outlet of the channel of the vacuum chamber wall; and a heat exchanger outlet that is fluidically coupled to the liquid pump; a diverter valve fluidically coupled between the channel inlet of the channel of the vacuum chamber wall and the outlet of the one or more fluidic tubing lines, channels or conduits that are in thermal contact with the vacuum pump housing; a tee-junction fluidically coupled between the heat exchanger inlet and the channel inlet of the channel of the vacuum chamber wall; and a bypass fluid tubing line or conduit fluidically coupled between the diverter valve and the tee-junction.

6. A system as recited in claim 5, further comprising: a temperature sensor within the vacuum system; and an electronic controller or computer configured to receive a temperature-dependent signal from the temperature sensor and configured to transmit a control signal to the diverter valve, wherein the electronic controller or computer comprises computer-readable instructions that are operable to cause transmission of the control signal in response to the temperature-dependent signal.

7. A system as recited in claim 6, wherein the control signal causes the diverter valve to deliver either all of, a portion of or none of a flow of a coolant liquid to the channel inlet of the channel of the vacuum chamber wall.

8. A system as recited in claim 5, wherein the vacuum chamber is a component of the group consisting of a mass spectrometer, an electron microscope and a chemical vapor deposition apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above noted and various other aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings, not necessarily drawn to scale, in which:

[0015] FIG. 1 is a schematic diagram of a portion of a general conventional mass spectrometer system;

[0016] FIG. 2 is a schematic illustration of a system, in accordance with the present teachings, for cooling a vacuum pump of the mass spectrometer system of FIG. 1;

[0017] FIG. 3 is a schematic illustration of a first system, in accordance with the present teachings, for cooling a vacuum pump and heating a vacuum chamber of the mass spectrometer system of FIG. 1; and

[0018] FIG. 4 is a schematic illustration of a second system, in accordance with the present teachings, for cooling a vacuum pump and heating a vacuum chamber of the mass spectrometer system of FIG. 1.

DETAILED DESCRIPTION

[0019] The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiments and examples shown but is to be accorded the widest possible scope in accordance with the features and principles shown and described. To fully appreciate the features of the present invention in greater detail, please refer to FIGS. 1-3 in conjunction with the following description.

[0020] In the description of the invention herein, it is understood that a word appearing in the singular encompasses its plural counterpart, and a word appearing in the plural encompasses its singular counterpart, unless implicitly or explicitly understood or stated otherwise. Furthermore, it is understood that, for any given component or embodiment described herein, any of the possible candidates or alternatives listed for that component may generally be used individually or in combination with one another, unless implicitly or explicitly understood or stated otherwise. Moreover, it is to be appreciated that the figures, as shown herein, are not necessarily drawn to scale, wherein some of the elements may be drawn merely for clarity of the invention. Also, reference numerals may be repeated among the various figures to show corresponding or analogous elements. Additionally, it will be understood that any list of such candidates or alternatives is merely illustrative, not limiting, unless implicitly or explicitly understood or stated otherwise.

[0021] The term “coolant liquid”, as used herein, refers to the liquid that is caused to flow within the fluid tubing lines, channels or other conduits that are portions of liquid circuits described herein. Depending upon the environment of any particular portion of such a liquid circuit, the coolant liquid within the portion may either absorb heat from the local environment, release heat to the local environment or possibly neither absorb nor release heat. For consistency, however, the liquid is referred to as a “coolant liquid” throughout. Unless otherwise defined, all other technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. It will be appreciated that there is an implied “about” prior to the quantitative terms mentioned in the present description, such that slight and insubstantial deviations are within the scope of the present teachings. In this application, the use of the singular includes the plural unless specifically stated otherwise. Also, the use of “comprise”, “comprises”, “comprising”, “contain”, “contains”, “containing”, “include”, “includes”, and “including” are not intended to be limiting. As used herein, “a” or “an” also may refer to “at least one” or “one or more.” Also, the use of “or” is inclusive, such that the phrase “A or B” is true when “A” is true, “B” is true, or both “A” and “B” are true.

[0022] FIG. 2 is a schematic illustration of a system, in accordance with the present teachings, for cooling a vacuum pump of a scientific or industrial apparatus. Although illustrated with reference to the mass spectrometer system of FIG. 1, the vacuum pump cooling system of FIG. 1 and the principle of operation of this system is applicable to other scientific and industrial apparatuses that employ vacuum chambers that are evacuated by one or more vacuum pumps. To avoid a confusion of components and to emphasize the general applicability of the present teachings, only a limited number of mass-spectrometer-specific components are included in FIG. 2 (and FIG. 3). The illustrated mass spectrometer components are the ionization chamber 14, the ion transfer tube 16 and the skimmer 21.

[0023] The system 40 of FIG. 2 comprises a fluid circuit that includes a liquid pump 43, a heat exchanger 46 and various fluid tubing lines, channels or conduits 47a, 47b and 47c. The liquid pump 43 expels a coolant liquid, that may comprise, without limitation, water and/or ethylene glycol, into fluid tubing line 47a which, in the illustrated embodiment, transfers the coolant liquid into the chassis/housing 8 and into the vicinity of a motor housing 5 of the vacuum pump 10. The coolant liquid is transferred from the fluid tubing line 47a into a tubing, channel or other conduit 47b that is in thermal contact with the motor housing 5. The coolant liquid within the tubing, channel or conduit 47b extracts heat from the pump 10, thereby increasing the temperature of the coolant liquid. The so-warmed coolant liquid is then transferred to an inlet 33 of the heat exchanger 46 through fluid tubing line 47c. The heat exchanger 46, which may be of any suitable known type, is in thermal contact with either an ambient-temperature air bath, a chilled air bath or a liquid bath that extracts heat from the coolant liquid as that liquid passes through one or more fluid channels, tubes or other conduits within the heat exchanger. The so-chilled coolant liquid exits from an outlet 34 of the heat exchanger 46 and is transferred back to the pump 43 by fluid tubing line 47d, thus completing the fluid circuit.

[0024] Many types of heat exchangers are known in the art and may be used within the system 40. If the heat exchanger 46 is in thermal contact with an air bath (either at ambient temperature or chilled), then a fan may be employed so as to maintain a constant flow of air over about or through the heat exchanger. In contrast to conventional fan-based methods of cooling a vacuum pump, the provision of the fluid tubing lines, channels or conduits 47a, 47b and 47c enables the fan to be located remotely from the vacuum pump and its associated apparatus or even remotely from the laboratory environment. The remote placement of the fan may prevent noise and vibrations from interfering with apparatus or laboratory operations.

[0025] Preferably, the tubing, channel or conduit 47b comprises one or more fluid channels or other conduits within the body of the motor housing 5. Alternatively, the tubing, channel or conduit 47b may comprise a metal tube of high thermal conductivity, such as a copper or aluminum that is affixed to the outer surface of the motor housing 5, such as by solder. Such a tubing configuration is schematically illustrated in FIG. 2, showing several windings of the affixed tubing around the surface of the motor housing. As another alternative, the tubing, channel or conduit 47b may comprise a conduit or series of conduits within a specialized heat exchanger (for instance, a collar) that is designed to attach to and mate with the motor housing. The alternative configurations described above are appropriate in situations when the tubing, channel or conduit 47b is installed onto an existing vacuum pump when it is desired not to modify the vacuum pump proper.

[0026] Although FIG. 2 depicts only the single vacuum pump 10 as a heat-generating component within the apparatus housing 8, there will generally be additional heat-generating components disposed within the housing. For example, if the apparatus is a mass spectrometer as depicted in FIG. 1, then one or more additional vacuum pumps (such as a diffusion pump and/or a turbo-molecular pump, not shown) may be included within the housing in order to further evacuate compartment 26 through vacuum port 19 as well as to evacuate any additional compartments. Heat-generating electronics and additional motors (not shown) may also be disposed within the housing 8. Accordingly, in many instances, the fluid circuit that transports the coolant liquid may be extended so as to also sequentially come into thermal contact with the other heat-generating components inside the housing in order to off-load waste heat to the cooling fluid circuit.

[0027] FIG. 3 is a schematic illustration of a system, in accordance with the present teachings, for cooling a vacuum pump while, at the same time, heating a vacuum chamber of a scientific or industrial apparatus that employs a vacuum chamber. With similarity to the depiction of FIG. 2, the mass spectrometer system of FIG. 1 is illustrated in FIG. 3 as a representative of a scientific instrument of this type, with most of the mass-spectrometer-specific components removed from the diagram. The system 50 depicted in FIG. 3 comprises the liquid pump 43, the heat exchanger 46 and the fluid tubing lines, channels or conduits 47a, 47b and 47c as already described in reference to FIG. 2. Further, as noted above with regard to FIG. 2, the fluid circuit may also come into thermal contact with the other heat-generating components (not shown) inside the chassis/housing 8. However, in contrast to the system 40 depicted in FIG. 2, the fluid tubing line 47c does not directly deliver the heated coolant liquid to the heat exchanger 46. Instead, in the system 50, the fluid tubing line 47c terminates at a diversion valve 44. The diversion valve 44 is configured to deliver the entire flow of the heated coolant liquid to either fluid tubing line, channel or other conduit 47d or to fluid tubing line, channel or other conduit 47e or, alternatively, to apportion the flow of the heated coolant liquid between the two fluid pathways 47d, 47e. Any coolant liquid that is delivered to the fluid tubing line, channel or conduit 47d by the valve 44 is caused to also pass through a tee-junction 45 and a fluid tubing line 47g so as to thereby return to the inlet 33 of heat exchanger 46. Any coolant liquid that is delivered to the fluid tubing line, channel or conduit 47e by the valve 44 is caused to pass into and through one or more channels, conduits or fluid tubing lines 41 either embedded within or otherwise in thermal contact with the body of the vacuum chamber 3. This coolant liquid then passes through tee-junction 45 and fluid tubing line 47g so as to thereby return to the inlet 33 of heat exchanger 46. Upon exiting the heat exchanger at outlet 34, the coolant liquid returns to the pump 43 through fluid tubing line 47h.

[0028] Having acquired heat energy from the vacuum pump 10, any so-heated coolant liquid that subsequently passes through fluid tubing line 47c and that is diverted into the one or more channels, conduits or fluid tubing lines 41 then releases all or a portion of this heat energy to the vacuum chamber 3. As a consequence, a portion of the heat energy is imparted to the compartments 18, 26 therein (assuming that the chamber and compartments are at a lower temperature than the heated coolant). The heating of gas within the compartments improves pumping efficiency and enables the attainment of lower pressures than would otherwise be achieved. Although flow through the one or more channels, conduits or fluid tubing lines 41 is depicted as being unidirectional through a single wall of the vacuum chamber 3 in FIG. 3, the conduits or fluid tubing lines may extend around or within multiple walls and may include one or more bends within or adjacent to each such wall in order to maximize the wall surface area that is in thermal contact with the coolant liquid. If there is an anticipated temperature gradient along the vacuum chamber, then the conduits or fluid tubing lines may be configured to direct the flow of coolant liquid first to cooler portions of the chamber and then to warmer sections so as to reduce or eliminate the gradient.

[0029] The temperature of the vacuum chamber interior or of one or more of its compartments may be measured by one or more temperature sensors 48a and regulated by a control system to maintain a set temperature (or temperature range) within the vacuum chamber 3. Non-limiting examples of suitable temperature sensors include thermocouple and thermistor sensors. The one or more temperature sensors 48a may be in electronic communication with a computer or other electronic controller 49 whereby a signal from the temperature sensor may be digitized, if the signal was previously in analog form. Similarly, the heat exchanger 46 may comprise one or more temperature sensors 48b that measure the temperature(s) of one or more of the air or liquid bath, the ambient environment, the coolant liquid at the inlet 33 and the coolant liquid at the outlet 34. The one or more temperature sensors 48b may be in electronic communication with the computer or other electronic controller 49 and analog signals, if any, from the one or more temperature sensors 48b may be digitized by the computer or other electronic controller. Further one or both of the diversion valve 44 and the liquid pump 43 may be in electronic communication with the computer or other electronic controller 49. Other temperature sensors (not shown) may be disposed so as to measure temperatures elsewhere in the system, such as at various locations within the fluid tubing lines, channels or conduits 47a, 47b and 47c.

[0030] The computer or other electronic controller 49 may comprise a separate general-purpose computer that is electronically coupled to the various physical components or may comprise electronic logic components and associated circuitry within the apparatus. The computer or other electronic controller 49 may comprise computer-readable instructions, either software-based or in firmware, that are operable to read and/or record temperature-related signals from the various temperature sensors and that are further operable, in response to the temperature signals, to control the operation of the liquid pump 43, the operation of the diversion valve 44 and/or the temperature of a liquid or air bath in contact with the heat exchanger 46. The operation of the liquid pump, diversion valve and/or heat exchanger bath fluid may be performed by control signals delivered to one or more of the liquid pump, diversion valve and heat exchanger over one or more electrical wires or cables (not shown) that couple these components to the computer or other electronic controller 49. One or more of the temperature(s) may be monitored and this information may be used to control either the temperature or the rate of flow of heated coolant liquid that passes through the conduits or fluid tubing lines 41 as the chamber temperature changes. The flow rate may be controlled by either the pumping speed or by the apportioning of flow between fluid tubing lines, channels or conduits 47d and 47e. This technique provides a method to control the operating temperature of the chamber and avoid overheating in this area of the instrument. Once the desired chamber temperature is reached, either the pumping speed of the pump 43 may be reduced or the diverter valve 44 may be configured to send more of the heated coolant liquid to fluid tubing line, channel or conduit 47d and then to the external heat exchanger 46.

[0031] According to a variation of the system 50 (not shown), both the temperature sensor 48a and the controller 49 may be replaced by a simple analog thermostat, such as a thermostat of the bi-metal type. The thermostat may act as an electrical switch that is directly coupled to an actuator of the diversion valve 44. In operation, the thermostatic switch may cause the diversion valve to send coolant liquid through the one or more channels, conduits or fluid tubing lines 41 when the internal chamber temperature exceeds a pre-determined set point and to send the coolant liquid through the bypass fluid tubing line 47d otherwise. The additional one or more temperature sensors 48b may be absent from such a system.

[0032] FIG. 4 is a schematic illustration of a second system, in accordance with the present teachings, for cooling a vacuum pump and heating a vacuum chamber of the mass spectrometer system of FIG. 1. The system 60 depicted in FIG. 4 differs from the system 50 of FIG. 3 in that the system 60 does not include any of the diversion valve 44, the tee-junction 45 and the fluid tubing lines 47e, 47f. Instead, within the system 60, the fluid tubing line 47c delivers coolant liquid directly to an inlet of the one or more channels, conduits or fluid tubing lines 41 and the fluid tubing line 47g directly receives the coolant liquid from an outlet of the one or more channels, conduits or fluid tubing lines 41. Accordingly, the heated coolant liquid continuously flows through the one or more channels, conduits or fluid tubing lines. During operation of the system 60, the temperature control system operates to control a variable speed fan 61, such as by transmitting a control signal to the fan over electrical wires or cables (not shown), that sends air flow onto or across a portion of the exterior of the vacuum chamber 3. The control system increases the air flow provided by the fan 61 if the chamber temperature rises and reduces the air flow if the chamber temperature decreases. The temperature control system may also operate to similarly control the pumping speed of the liquid pump 43. The variable speed fan 61 is smaller than fans that are used to cool the vacuum pump 10 in conventional systems, since a portion of the heat that is generated by the vacuum pump is absorbed by the vacuum chamber 3 and the heat exchanger 46. The variable speed fan therefore utilizes less electrical power and produces less noise and vibration than do fans of conventional systems.

[0033] Improved systems and methods have been herein disclosed for removing heat from a vacuum pump of an apparatus that includes a vacuum chamber. Various embodiments of the systems and methods in accordance with the present teachings make use of the heat energy that is received from the vacuum pump by transporting at least a portion of the heat to the vacuum chamber and thereby improving pumping efficiency. The discussion included in this application is intended to serve as a basic description. The present invention is not intended to be limited in scope by the specific embodiments described herein, which are intended as single illustrations of individual aspects of the invention. Functionally equivalent methods and components are within the scope of the invention. For example, although a heat exchanger 46 has been illustrated as being disposed outside of a housing 8 of an apparatus in question, some applications may require the heat exchanger to be disposed within the housing (e.g. for purposes of overall apparatus compactness or because an external heat exchanger is not available or feasible). Similarly, the liquid pump 43 may be disposed within the apparatus housing. As another example, although the present teachings are generally applicable to an apparatus that includes a vacuum pump within the apparatus housing, some applications may require the vacuum pump to be disposed on its own separate chassis and within its own separate housing (e.g., for purposes of vibration isolation or structural support of a heavy vacuum pump. In such instances, removal of heat from the vacuum pump may be necessary or required in order to avoid overheating and, in such instances, the principles and features taught herein will still apply. Various other modifications of the invention, in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and accompanying drawings.

[0034] Any patents, patent applications, patent application publications or other literature mentioned herein are hereby incorporated by reference herein in their respective entirety as if fully set forth herein, except that, in the event of any conflict between the incorporated reference and the present specification, the language of the present specification will control.