FIELD OF THE INVENTION

The present invention relates to pumping systems that use an oil, for example to lubricate and/or cooling dynamic parts of the pumping system.

BACKGROUND

Dry vacuum pumps are pumps that do not use any liquids in the main pumping stages to create a vacuum or provide cooling within the pump to maintain specific required operating temperature. Dry vacuum pumps are used in various different industries (e.g. in semi-conductor fabrication).

Mechanical booster pumps are used with other pumps, such as dry vacuum pumps, to “boost” the pumping speed of those other pumps.

It tends to be desirable for a pump to have lower power consumption for a given pumping performance.

SUMMARY OF INVENTION

In dry vacuum pumps, there tends to be no lubrication (e.g. without an oil) in the main pumping stage, thus reducing or eliminating contamination of a pumped process gas. However, oil may be used to provide lubrication and/or cooling in other parts of the dry vacuum pump. For example, oil may be used to provide lubrication in a gearbox coupled between the main pumping stage and a motor that drives the dry vacuum pump, and/or in an end cover of the dry vacuum pump. The oil may be used to lubricate moving parts of pump, such as at both ends of a rotating shaft, gears and bearings. The oil may be sprayed onto various parts using, for example, an oil splitter rotating with the shaft in the gearbox and end cover.

Other types of pumps, such as mechanical booster pumps, also use oil to provide lubrication. The present inventors have realised that a reduction in power consumption of a vacuum pumping system can be achieved by controlling the temperature of oil used in the system. The temperature of the lubrication oil tends to affect the flow characteristics of the oil. A relatively low temperature lubrication oil tends to have a relatively high viscosity which tends to restrict oil flow to bearings and other machine elements, inhibit effective spraying, and also increase dynamic resistance. The present inventors have realised that controlling the temperature of oil to be relatively high (e.g. an optimum operating temperature) tends to overcome these problems. In a first aspect, the present invention provides a system comprising: a pump; an oil located within at least a part of the pump, the oil providing lubrication and/or within the at least part of the pump; a temperature sensor configured to measure a temperature of the oil; cooling means configured to cool the at least a part of the pump; and a controller. The controller is configured to: receive, from the temperature sensor, a measurement of the temperature of the oil; and control the cooling means based on the received temperature measurement.

The controller may be configured to compare the received temperature measurement to a temperature threshold, and control the cooling means based on the comparison. The controller may be configured to, if the received temperature measurement is greater than the temperature threshold, control the cooling means to begin cooling or continue to cool the at least a part of the pump. The controller may be configured to, if the received temperature measurement is less than or equal to the temperature threshold, control the cooling means to reduce cooling of the at least a part of the pump. The controller may be configured to, if the received temperature measurement is greater than the temperature threshold, control the cooling means to increase cooling of the at least a part of the pump. The controller may be configured to, if the received temperature measurement is less than or equal to the temperature threshold, control the cooling means to stop cooling of the at least a part of the pump.

The temperature threshold may be between 80Ό and 90 ^° C, e.g. about or exactly 85 ^° C. The temperature threshold may be defined by the temperature at which the oil has optimum viscosity for lubrication and/or cooling of the at least part of the pump. Testing may be performed to determine an optimum viscosity of the oil, an oil evaporation rate (e.g. a temperature at which oil evaporation is at a minimum), and/or a desired or optimum temperature for the main pumping stage. The temperature threshold may be determined based on this testing. The temperature threshold may be defined to be less than or equal to a maximum allowed threshold value. This maximum allowed threshold value may be a temperature at which properties of the oil begin to become unacceptable and/or a temperature corresponding to an unacceptably high temperature of the main pumping stage.

The at least a part of the pump may be a part selected from the group consisting of: a gearbox, an end cover, and a combination of the gearbox and the end cover. The cooling means may comprise one or more conduits passing through one or more of the gearbox and the end cover, and a cooling fluid supply configured to cause a cooling fluid to flow through the one or more conduits.

The pump may be a pump selected from the group consisting of a mechanical booster pump, a vacuum pump, and a dry vacuum pump.

The system may further comprise a motor configured to drive the pump, and further cooling means configured to cool the motor. The further cooling means may be independent and/or separate from the cooling means.

The pump may comprise a pumping stage. The system may further comprise second further cooling means configured to cool at least a part of the pumping stage. The second further cooling means may be independent and/or separate from the cooling means.

The oil may be an oil selected from the group of oils consisting of: an oil that is any combination of a non-flammable, chemically inert, and thermally stable; a mineral oil that has been through a distillation process to reduce its vapor pressure; a vacuum pump oil; an inert vacuum pump oil; a Fomblin® PFPE vacuum pump oil; a Fomblin® YL-VAC inert vacuum pump fluid; a Fomblin® YL-VAC RP inert vacuum pump fluid; a Fomblin® SV inert vacuum pump fluid; a Fomblin® YFI-VAC inert vacuum pump fluid, and Fomblin® DRYNERT 25/6 oil.

The system may further comprise: a further pump; a further oil located within at least a part of the further pump; a further temperature sensor configured to measure a temperature of the further oil; and further cooling means configured to cool the at least a part of the further pump. The controller may be further configured to: receive, from the further temperature sensor, a measurement of the temperature of the further oil; and control the further cooling means based on the received temperature measurement of the further oil.

The system may further comprise one or more further temperature sensors configured to measure a temperature of the oil. The controller may be configured to: receive, from the one or more temperature sensor, respective further measurements of the temperature of the oil; and control the cooling means based on some function of the received temperature measurement and the one or more received further measurements.

The cooling means may be configured to supply a cooling fluid to the at least a part of the pump. The system may further comprise a heater configured to heat the cooling fluid prior to the cooling fluid being received by the at least a part of the pump. The controller may be configured to control the heater based on the received temperature measurement.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a schematic illustration (not to scale) of a conventional pumping system; and

Figure 2 is a schematic illustration (not to scale) of a pumping system that implements oil temperature control.

DETAILED DESCRIPTION

In the Figures, like reference numerals refer to like elements. Figure 1 is a schematic illustration (not to scale) of a conventional pumping system 100.

The conventional pumping system 100 comprises a mechanical booster pump 102 and a dry vacuum pump 104. The mechanical booster pump 102 and the dry vacuum pump 104 are arranged to pump a process gas from a facility (not shown in the Figures). The mechanical booster pump 102 is mechanically coupled to the dry vacuum pump 104 via a coupling mechanism (not shown in the Figures). The mechanical booster pump 102 is configured to increase the pressure of the process gas entering the dry vacuum pump 104. Operation of the mechanical booster pump 102 tends to increase the pumping effectiveness of the dry vacuum pump 104.

The mechanical booster pump 102 comprises a first end cover 106, a first main pumping stage 108, a first gearbox 110, a first motor 112, and a first heat sink 114. In this example, the first motor 112 is coupled to the first gearbox 110.

The first motor 112 is configured to drive, via the first gearbox 110, a drive shaft (not shown in the Figures) located within the first main pumping stage 108. An impeller is mounted to the drive shaft within the first main pumping stage 108. The first end cover 106 is coupled to, and supports, the drive shaft, at an opposite end of the first main pumping stage 108 to the side at which the first gearbox 110 and the first motor 112 are located.

Rotation of the driveshaft and impeller mounted thereto within the first main pumping stage 108 by the first motor 112, causes the process gas to be pumped, by the mechanical booster pump 102, from the facility to the dry vacuum pump 104.

In this example, the first heat sink 114 is coupled to an external surface of the first main pumping stage 108. The first heat sink 114 is coupled to a first cooling fluid source 116. The first heat sink 114 is configured to receive a first cooling fluid from the heat cooling fluid source 116. The first cooling fluid flows from the first cooling fluid source 116, through the first heat sink 114, and out of the first heat sink 114, as indicated in Figure 1 by a dashed arrow and the reference numeral 118. In operation, heat is transferred from the first main pumping stage 108 to the first cooling fluid flowing through the first heat sink 114. Thus, the first main pumping stage 108 is cooled.

The first cooling fluid may be any appropriate type of cooling fluid, preferably water, although type of cooling fluid may be used such as a cool gas, ethylene glycol, and/or an oil.

In this example, the mechanical booster pump 102 further comprises one or more first conduits 120. The one or more first conduits 120 pass through the first motor 112, the first gearbox 110, and the first end cover 106. The one or more first conduits 120 are coupled to a second cooling fluid source 122. The one or more first conduits 120 are configured to transfer a second cooling fluid from the second cooling fluid source 122 to the first motor 112, the first gearbox 110, and the first end cover 106. Thus, in operation, the second cooling fluid passes from the second cooling fluid source 122 to each of the first motor 112, the first gearbox 110, and the first end cover 106 in turn (as indicated in Figure 1 by arrows along the first conduits 120). In operation, heat is transferred from the components of the first motor 112, the first gearbox 110, and the first end cover 106 to the second cooling fluid flowing through the one or more first conduits 120. Thus, the components of the first motor 112, the first gearbox 110, and the first end cover 106 are cooled. In addition, oil (e.g. lubricant) present in the first motor 112, the first gearbox 110, and/or the first end cover 106 tends to be cooled by the second cooling fluid flowing through the one or more first conduits 120. This cooling of the oil may increase the viscosity of the oil which tends to restrict the flow of the oil to bearings and other dynamic elements, inhibit effective spraying of the oil, and also increase dynamic resistance.

In this example, the one or more first conduits 120 by-pass the first main pumping stage 108. Thus, the second cooling fluid does not flow through the first main pumping stage 108. The first main pumping stage 108 is not cooled by the flow of the second cooling fluid. The second cooling fluid may be any appropriate type of cooling fluid, e.g. water. ln this example, the mechanical booster pump 102 is a single-stage pump. However, it will be appreciated by those skilled in the art that the mechanical booster pump 102 may be a multi-stage pump.

The dry vacuum pump 104 comprises a second end cover 126, a second main pumping stage 128, a second gearbox 130, a second motor 132, and a second heat sink 134.

In this example, the second motor 132 is coupled to the second gearbox 130. The second motor 132 is configured to drive, via the second gearbox 130, a drive shaft (not shown in the Figures) located within the second main pumping stage 128. An impeller is mounted to the drive shaft within the second main pumping stage 128. The second end cover 126 is coupled to, and supports, the drive shaft, at an opposite end of the second main pumping stage 128 to the side at which the second gearbox 130 and the second motor 132 are located.

Rotation of the driveshaft and impeller mounted thereto within the second main pumping stage 128 by the second motor 132, causes the process gas to be pumped, by the dry vacuum pump 104, from the mechanical booster pump 102 to a location remote from the conventional pumping system 100.

In this example, the second heat sink 134 is coupled to an external surface of the second main pumping stage 128. The second heat sink 134 is coupled to both top and bottom side of the second main pumping stage 128. The second heat sink 134 is coupled to a third cooling fluid source 136. The second heat sink 134 is configured to receive a third cooling fluid from the third cooling fluid source 136. The third cooling fluid flows from the third cooling fluid source 136, through the second heat sink 134, and out of the second heat sink 134, as indicated in Figure 1 by a dashed arrow and the reference numeral 138.

In operation, heat is transferred from the second main pumping stage 128 to the third cooling fluid flowing through the second heat sink 134. Thus, the second main pumping stage 128 is cooled.

The third cooling fluid may be any appropriate type of cooling fluid, e.g. water.

In this example, the dry vacuum pump 104 further comprises one or more second conduits 140. The one or more second conduits 140 pass through the second motor 132, the second gearbox 130, and the second end cover 126. The one or more second conduits 140 are coupled to a fourth cooling fluid source 142. The one or more second conduits 140 are configured to transfer a fourth cooling fluid from the fourth cooling fluid source 142 to the second motor 132, the second gearbox 130, and the second end cover 126. Thus, in operation, the fourth cooling fluid passes from the fourth cooling fluid source 142 to each of the second motor 132, the second gearbox 130, and the second end cover 126 in turn. In operation, heat is transferred from the components of the second motor 132, the second gearbox 130, and the second end cover 126 to the fourth cooling fluid flowing through the one or more second conduits 140. Thus, the components of the second motor 132, the second gearbox 130, and the second end cover 126 are cooled. In addition, oil (e.g. lubricant) present in the second motor 132, the second gearbox 130, and/or the second end cover 126 tends to be cooled by the fourth cooling fluid flowing through the one or more second conduits 140. This cooling of the oil may increase the viscosity of the oil which tends to restrict the flow of the oil to bearings and other dynamic elements, inhibit effective spraying of the oil, and also increase dynamic resistance.

In this example, the one or more second conduits 140 by-pass the second main pumping stage 128. Thus, the fourth cooling fluid does not flow through the second main pumping stage 128. The second main pumping stage 128 is not cooled by the flow of the fourth cooling fluid.

The fourth cooling fluid may be any appropriate type of cooling fluid, e.g. water. In this example, the dry vacuum pump 104 is a multi-stage pump.

However, it will be appreciated by those skilled in the art that the dry vacuum pump 104 may be a single-stage pump.

Figure 2 is a schematic illustration (not to scale) showing an embodiment of a pumping system 200. Elements common to the pumping systems 100, 200 of Figures 1 and 2 are indicated using the same reference numerals.

In this embodiment, the pumping system 200 comprises the mechanical booster pump 102 (including the first end cover 106, the first main pumping stage 108, the first gearbox 110, the first motor 112, and the first heat sink 114) and the dry vacuum pump 104 (including the second end cover 126, the second main pumping stage 128, the second gearbox 130, the second motor 132, and the second heat sink 134), which are configured as described in more detail earlier above for the conventional pumping system 100, with reference to Figure 1.

In this embodiment, the pumping system 200 further comprises one or more third conduits 202, a fifth cooling fluid source 204, a first temperature sensor 206, a second temperature sensor 208, a controller 210, one or more fourth conduits 212, a sixth cooling fluid source 214, one or more fifth conduits 216, and a seventh cooling fluid source 218.

The one or more third conduits 202 pass through the second motor 132 and the first motor 112. The one or more third conduits 202 are coupled to the fifth cooling fluid source 204. The one or more third conduits 202 are configured to transfer a fifth cooling fluid from the fifth cooling fluid source 204 to the second motor 132 and the first motor 112. Thus, in operation, the fifth cooling fluid passes from the fifth cooling fluid source 204 to each of the second motor 132 and the first motor 112, in turn. In operation, heat is transferred from the components of the second motor 132 and the first motor 112 to the fifth cooling fluid flowing through the one or more third conduits 202. Thus, the components of the second motor 132 and the first motor 112 are cooled.

In this example, the one or more third conduits 202 pass through only the first and second motors 112, 132, i.e. they do not pass through the any of the gearboxes 110, 130, the pumping stages 108, 128, or the end covers 106, 126. Thus, the fifth cooling fluid does not flow through gearboxes 110, 130, the pumping stages 108, 128, or the end covers 106, 126, which are thus not cooled by the flow of the fifth cooling fluid. Cooling of the motors 112, 132 tends to be independent to that of the other system parts.

The fifth cooling fluid may be any appropriate type of cooling fluid, e.g. water.

The one or more fourth conduits 212 pass through the first end cover 106 and the first gearbox 110. The one or more fourth conduits 212 are coupled to the sixth cooling fluid source 214. The one or more fourth conduits 212 are configured to transfer a sixth cooling fluid from the sixth cooling fluid source 214 to the first end cover 106 and the first gearbox 110. The sixth cooling fluid then exits the system 200. Thus, in operation, the sixth cooling fluid passes from the sixth cooling fluid source 214 to each of the first end cover 106 and the first gearbox 110 in turn (as indicated in Figure 2 by arrows along the fourth conduits 212). In operation, heat is transferred from the components of the first end cover 106 and the first gearbox 110 to the sixth cooling fluid flowing through the one or more fourth conduits 212. Thus, the components of the first end cover 106 and the first gearbox 110 are cooled.

In addition, oil (e.g. lubricant) present in the first end cover 106 and the first gearbox 110 tends to be cooled by the sixth cooling fluid flowing through the one or more fourth conduits 212.

The first temperature sensor 206 is coupled to the first end cover 106. The first temperature sensor 206 is configured to measure a temperature of the oil (i.e. the lubricant) within the first end cover 106. The measurements of the temperature of the oil within the first end cover 106 taken by the first temperature sensor 206 are hereafter referred to as “first temperature measurements”. In some embodiments, the first temperature sensor 206 may be coupled to the first end cover 106 and may be configured to measure a temperature of oil that is sprayed onto the dynamic components of the first end cover 106. The temperature measured by the first temperature sensor 206 within the first end cover 106 is representative of oil temperature in the first end cover 106. The first temperature sensor 206 may be any appropriate type of temperature sensor, such as a thermistor, or a thermocouple. In this embodiment, the first temperature sensor 206 is coupled (e.g. via a wired or wireless link) to the controller 210 such that the first temperature measurements are sent to the controller 210.

In addition to being coupled to the first temperature sensor 206, the controller 210 is coupled to the sixth cooling fluid source 214 via a wired or wireless link. The controller 210 is configured to control operation of the sixth cooling fluid source 214. In this embodiment, the controller 210 is configured to receive the first temperature measurements, and to control operation of the sixth cooling fluid source 214 based on the received first temperature measurements. More specifically, the controller 210 is configured to compare the first temperature measurements to a first temperature threshold. If the first temperature measurements are less than or equal to the first threshold temperature, the controller 210 controls the sixth cooling fluid source 214 to stop supplying the sixth cooling fluid, i.e. such that the flow of the sixth cooling fluid along the one or more fourth conduits 212 is slowed, and preferably stopped. This tends to reduce cooling to the first end cover 106 and the first gearbox 110, thus allowing the temperature of the oil therein to increase. On the other hand, if the first temperature measurements are greater than the first threshold temperature, the controller 210 controls the sixth cooling fluid source 214 to supply or continue to supply the sixth cooling fluid, i.e. such that the flow of the sixth cooling fluid along the one or more fourth conduits 212 is started or continued, and may be increased. This tends to provide cooling to the first end cover 106 and the first gearbox 110, thus cooling the oil therein.

Control of the supply of the sixth cooling fluid in this way tends provide that the temperature of the oil within the first end cover 106 is maintained at a temperature approximately equal to the first threshold temperature. Also, the oil within the first gearbox 110 may be maintained at a temperature approximately equal to (or slightly higher than) the first threshold temperature.

In this embodiment, the first threshold temperature is 85Ό. Advantageously, maintaining oil temperature at 85Ό tends to provide for reduced power consumption (and, indeed, substantially optimum reduced power consumption) of the mechanical booster pump 102. The oil lubricant present in the first gearbox 110 and/or the first end cover 106 tends have reduced viscosity. Thus, flow of the oil tends to be improved, effective spraying tends to facilitated, and resistance within the first gearbox 110 and/or the first end cover 106 tends to be reduced. Nevertheless, it will be appreciated by those skilled in the art that a different value may be used for the first threshold temperature, e.g. a value less than 85Ό, or a value greater than 85Ό, or a value between 84 ^° C and 86 ^° C, or a value between 83Ό and 87 ^° C, or a value between 82 ^° C and 88Ό, or a value between 81 ^° C and 89 ^° C, or a value between 80Ό and 90 ^° C. Example threshold values include, but are not limited to, 80 ^° C, 81 ^° C, 82 ^° C, 83 ^° C, 84 ^° C, 85 ^° C, 86Ό, 87Ό, 88Ό, 89Ό, 90 ^° C. Reductions in power consumption tend to occur, at least to some extent, at temperatures other than 85 ^° C, etc., and may depend on the type of oil lubricant being used.

The first threshold temperature may be an optimum operating temperature, that may be determined by an appropriate process, such as by experimentation. The one or more fourth conduits 212 by-pass the first main pumping stage 108. Thus, the sixth cooling fluid does not flow through the first main pumping stage 108. The first main pumping stage 108 is not cooled by the flow of the sixth cooling fluid. Also, the one or more fourth conduits 212 do not pass through the first motor 112 and the sixth cooling fluid does not flow through the first motor 112. As such, cooling of the first motor 112 is not affected by the switching on/off of the sixth cooling fluid source 214. Continuous and effective cooling of the first motor 112 is instead provided by the one or more third conduits 202 and the fifth cooling fluid source 204.

The sixth cooling fluid may be any appropriate type of cooling fluid, e.g. water.

The one or more fifth conduits 216 pass through the second end cover 126 and the second gearbox 130. The one or more fifth conduits 216 are coupled to the seventh cooling fluid source 218. The one or more fifth conduits 216 are configured to transfer a seventh cooling fluid from the seventh cooling fluid source 218 to the second end cover 126 and the second gearbox 130. The seventh cooling fluid then exits the system 200. Thus, in operation, the seventh cooling fluid passes from the seventh cooling fluid source 218 to each of the second end cover 126 and the second gearbox 130 in turn (as indicated in Figure 2 by arrows along the fifth conduits 216). In operation, heat is transferred from the components of the second end cover 126 and the second gearbox 130 to the seventh cooling fluid flowing through the one or more fifth conduits 216. Thus, the components of the second end cover 126 and the second gearbox 130 are cooled. In addition, oil (e.g. lubricant) present in the second end cover 126 and the second gearbox 130 tends to be cooled by the seventh cooling fluid flowing through the one or more fifth conduits 216.

The second temperature sensor 208 is coupled to the second end cover 126. The second temperature sensor 208 is configured to measure a temperature of the oil (i.e. the lubricant) within the second end cover 126. The measurements of the temperature of the oil within the second end cover 126 taken by the second temperature sensor 208 are hereafter referred to as “second temperature measurements”. In some embodiments, the second temperature sensor 208 may be coupled to the second end cover 126 and may be configured to measure a temperature of oil that is sprayed onto the dynamic components of the second end cover 126. The temperature measured by the second temperature sensor 208 within the second end cover 126 is representative of oil temperature in the second end cover 126. The second temperature sensor 208 may be any appropriate type of temperature sensor, such as a thermistor, or a thermocouple. In this embodiment, the second temperature sensor 208 is coupled (e.g. via a wired or wireless link) to the controller 210 such that the second temperature measurements are sent to the controller 210. In addition to being coupled to the second temperature sensor 208 (and the first temperature sensor 206, and the sixth cooling fluid source 214), the controller 210 is coupled to the seventh cooling fluid source 218 via a wired or wireless link. The controller 210 is configured to control operation of the seventh cooling fluid source 218. In this embodiment, the controller 210 is configured to receive the second temperature measurements, and to control operation of the seventh cooling fluid source 218 based on the received second temperature measurements. More specifically, the controller 210 is configured to compare the second temperature measurements to a second temperature threshold. If the second temperature measurements are less than or equal to the second threshold temperature, the controller 210 controls the seventh cooling fluid source 218 to stop supplying the seventh cooling fluid, i.e. such that the flow of the seventh cooling fluid along the one or more fifth conduits 216 is slowed, and preferably stopped. This tends to reduce cooling to the second end cover 126 and the second gearbox 130, thus allowing the temperature of the oil therein to increase. On the other hand, if the second temperature measurements are greater than the second threshold temperature, the controller 210 controls the seventh cooling fluid source 218 to supply or continue to supply the seventh cooling fluid, i.e. such that the flow of the seventh cooling fluid along the one or more fifth conduits 216 is started or continued, and may be increased. This tends to provide cooling to the second end cover 126 and the second gearbox 130, thus cooling the oil therein. Control of the supply of the seventh cooling fluid in this way tends provide that the temperature of the oil within the second end cover 126 is maintained at a temperature approximately equal to the second threshold temperature. Also, the oil within the second gearbox 130 may be maintained at a temperature approximately equal to (or slightly higher than) the second threshold temperature.

In this embodiment, the second threshold temperature is 85Ό. Advantageously, maintaining oil temperature at 85Ό tends to provide for reduced power consumption (and, indeed, substantially optimum reduced power consumption) of the dry vacuum pump 104. The oil lubricant present in the second gearbox 130 and/or the second end cover 126 tends have reduced viscosity. Thus, flow of the oil tends to be improved, effective spraying tends to facilitated, and resistance within the second gearbox 130 and/or the second end cover 126 tends to be reduced. Nevertheless, it will be appreciated by those skilled in the art that a different value may be used for the second threshold temperature, e.g. a value less than 85Ό, or a value greater than 85Ό, or a value between 84 ^° C and 86 ^° C, or a value between 83Ό and 87 ^° C, or a value between 82 ^° C and 88Ό, or a value between 81 ^° C and 89 ^° C, or a value between 80Ό and 90 ^° C. Example threshold values include, but are not limited to, 80 ^° C, 81 ^° C, 82 ^° C, 83 ^° C, 84 ^° C, 85 ^° C, 86Ό, 87Ό, 88Ό, 89Ό, 90 ^° C. Reductions in power consumption tend to occur, at least to some extent, at temperatures other than 85 ^° C, etc., and may depend on the type of oil lubricant being used. The second threshold temperature may be an optimum operating temperature, that may be determined by an appropriate process, such as by experimentation.

The one or more fifth conduits 216 by-pass the second main pumping stage 128. Thus, the seventh cooling fluid does not flow through the second main pumping stage 128. The second main pumping stage 128 is not cooled by the flow of the seventh cooling fluid. Also, the one or more fifth conduits 216 do not pass through the second motor 132 and the seventh cooling fluid does not flow through the second motor 132. As such, cooling of the second motor 132 is not affected by the switching on/off of the seventh cooling fluid source 218. Continuous and effective cooling of the second motor 132 is provided by the one or more third conduits 202 and the fifth cooling fluid source 204.

The seventh cooling fluid may be any appropriate type of cooling fluid, e.g. water. Advantageously, the above described system tends to provide vacuum pumps having lower power consumption for a given pumping performance.

Advantageously, the above-described system tends to allow for pump operation with relatively increased oil temperature, e.g. compared to conventional systems. The pump tends to operate at a higher temperature. Thus, the process gas being pumped by the pump tends to be less likely to condense in the pump, thus reducing the likelihood of blockages within the pump.

In some embodiments, the pump system comprises one or heaters configured to heat cooling fluid prior to that cooling fluid being provided to a pump. The one or more heaters may be controlled by the controller, e.g. based on measurements taken by one or more of the temperature sensors.

In the above embodiments, any appropriate type of oil may be used. Preferably, a non-flammable, chemically inert, and thermally stable oil is used. Examples of appropriate types of oil which may be used include, but are not limited to, a Fomblin® PFPE vacuum pump oil, Fomblin® YL-VAC inert vacuum pump fluids, Fomblin® YL-VAC RP inert vacuum pump fluids, Fomblin® SV inert vacuum pump fluids, Fomblin® YFI-VAC inert vacuum pump fluids, Fomblin® DRYNERT 25/6 oil, and a mineral oil that has been through a distillation process to reduce its vapor pressure.

In the above embodiments, the pump system comprises two pump coupled together, namely a mechanical booster pump and a dry vacuum pump. However, in other embodiments the pump system comprises a different number of pumps. For example, in some embodiments, only a single pump is implemented (for example, only a mechanical booster pump, or only a dry vacuum pump). In systems comprising multiple pumps, the pumps may be coupled together such that fluid is pumped from one pump to another pump, or the pumps may operate independently from one another.

In the above embodiments, an oil temperature control process is implemented in all pumps of the system, e.g. both the mechanical booster pump and the dry vacuum pump. However, in other embodiments the oil temperature control process is not implemented in all pumps of the system, and may be implemented in a proper subset of the pumps.

In the above embodiments, the pumping system comprises a mechanical booster pump and a dry vacuum pump. However, in other embodiments the pumping system comprises a different type of pump other than one or both of the mechanical booster pump and the dry vacuum pump. In some embodiments, the pump system comprises one or more pumps in which oil is used to provide lubrication (e.g. to dynamic components) within the main pumping chamber/stage. The above-described oil temperature control system and method may be used to control the temperature of oil within the main pumping chamber/stage. In the above embodiments, in a given pump, the oil temperature control system and method are used to control the temperature of oil within both the end cover and the gearbox of that pump. However, in other embodiments, the oil temperature control system and method are not used to control the temperature of oil within both the end cover and the gearbox of that pump. For example, the temperature of the oil within only the end cover (and not the gearbox) may be controlled. Alternatively, the temperature of the oil within only the gearbox (and not the end cover) may be controlled. In some embodiments, the temperature of oil within only a different portion (i.e. neither the end cover nor the gearbox) may be controlled.

In the above embodiments, for a given pump, multiple parts of that pump receive cooling fluid from a common cooling fluid source. For example, for a given pump, both the end cover and the gearbox receive cooling fluid from a common cooling fluid source. However, in other embodiments, each part of a pump may have a respective, different cooling fluid source. For example, the end cover and the gearbox may be arranged to receive cooling fluids from different sources. The cooling fluid may be different. The different cooling fluid sources may be independently controllable by the controller.

In the above embodiments, for a given pump, multiple parts of that pump receive cooling fluid in an order as described above. For example, for a given pump, cooling fluid flows to the end cover and then subsequently to the gearbox. However, in other embodiments, the multiple parts of a pump receive cooling fluid in a different order to that described above. For example, for one or more of the pumps, cooling fluid may flow first to the gearbox and then subsequently to the end cover.

In the above embodiments, the first threshold temperature is equal to the second threshold temperature. However, in other embodiments, the first threshold temperature is not equal to the second threshold temperature. One or both of the first threshold temperature and the second threshold temperature may have a value other than 85Ό.

In the above embodiments, each pump comprises a respective single temperature sensor. However, in other embodiments, one or more of the pumps comprises a different number of temperature sensors, i.e. multiple temperature sensors. The multiple temperature sensors may be located at different respective locations within or on the pump. For example, in some embodiments, a pump comprises a temperature sensor within its end cover configured to measure a temperature of oil within the end cover, and also another temperature sensor within its gearbox configured to measure a temperature of oil within the gearbox. The controller may be configured to control a supply of cooling fluid to the various parts of the pump based on temperature measurements taken from multiple temperature sensors. For example, the controller may control the cooling fluid supply based on some function (e.g. a mean) of multiple sensor measurements.

In the above embodiments, each pump comprises a temperature sensor located in its end cover. However, in other embodiments, one or more of the pumps comprises one or more temperature sensor at other locations instead of or in addition to in its end cover, e.g. in its gearbox, or along a cooling fluid conduit between the end cover and the gearbox.

REFERENCE NUMERAL KEY

100 - conventional pumping system 100.

102 - mechanical booster pump 104 - dry vacuum pump 106 -first end cover

108 - first main pumping stage 110 - first gearbox 112 - first motor 114 - first heat sink 116 -first cooling fluid source

118 - flow of first cooling fluid 120 - one or more first conduits 122 - second cooling fluid source 126 - second end cover 128 - second main pumping stage

130 - second gearbox 132 - second motor 134 - second heat sink 136 - third cooling fluid source 138 -flow of third cooling fluid

140 - one or more second conduits 142 - fourth cooling fluid source 200 - pumping system 202 - one or more third conduits 204 - fifth cooling fluid source

206 - first temperature sensor 208 - second temperature sensor 210 - controller

212 - one or more fourth conduits 214 - sixth cooling fluid source 216 - one or more fifth conduits

218 - seventh cooling fluid source