FIELD OF THE INVENTION

The field of the invention relates to a portable vacuum pump assembly and a mass spectrometer or other equipment evacuated by such an assembly.

BACKGROUND

The miniaturisation of vacuum pumps is part of ongoing research that provides the possibility of portable vacuum systems. An advantage of such systems includes the ability to provide portable mass spectrometers or other vacuum equipment allowing the monitoring and analysis of remote sites. Such portable vacuum equipment can have military applications monitoring for hazardous chemicals, airport security applications and medical applications allowing such devices to be disconnected from an external power supply while being moved between sites.

Although there are many applications for a portable vacuum system, there are technical reasons that make providing such a system challenging. In particular, there is often a requirement in such systems to maintain a good vacuum at all times to avoid contamination of the vacuum chamber and the associated clean up costs. Furthermore, many pumps, such as scroll pumps, stop instantly if the power is removed. Such an abrupt termination of rotation can cause damage to the system particularly where such a pump is being used as a backing pump for a turbomolecular pump. Thus, it is important in such systems that a reliable power supply can be maintained. One challenge with battery operated devices is the compromise between charging time, run time and weight. Smaller batteries provide faster charging and improved portability (size and weight) whilst larger batteries offer extended run times.

It would be desirable to provide a portable vacuum system with a reliable internal power supply. SUMMARY

A first aspect provides a portable vacuum pump assembly comprising: a vacuum pump; an internal power supply; and power control circuitry for providing an uninterrupted power supply to said vacuum pump; wherein said internal power supply comprises a removable primary power supply and a further power supply; and said power control circuitry is configured to maintain a continuous power supply to said vacuum pump such that a motor of said vacuum pump is continuously driven, said power control circuitry being configured to route power to said vacuum pump from said internal power supply by initially routing power from said primary power supply and on determining an imminent interruption in a supply of power from said primary power supply, switching to route power from said further power supply to said vacuum pump.

The inventor of the present invention recognised that the competing requirements of an internal power supply that is able to supply continuous power to a pump in a reliable manner while still retaining relatively low size and weight might be addressed by the use of two batteries within the supply along with control circuitry for controlling their deployment, In this way when one of the batteries was nearing the end of its capacity, the other power supply could be used to supply power to the pump, allowing the primary power supply to be changed for a newly charged power supply thereby ensuring a continuous power supply to the vacuum pump, allowing the vacuum to be maintained and the slowing of the pump and the associated, noise and power implications to be avoided. In this way runtime is increased, with a reduced weight and size of power supply on board the vacuum system.

It should be noted that the internal power supply is an“on-board” power supply, that is one associated with the vacuum pump assembly and comprises an energy storage means, which may comprise one or more batteries and/ or a capacitive electrical storage means such as supercapacitors. In addition to the energy storage means the internal power supply may comprise some electronic circuitry which may be there to avoid short circuits and/or communicate information regarding current properties of the power supply to the vacuum assembly and/or an external remote device. The internal power supply may also power any valves, pressure gauges or other equipment forming part of the portable vacuum pump assembly.

A portable vacuum system is one that is configured such that it can be moved between and operated in different locations in a way that is not onerous. Thus, it is relatively compact and the system has its own internal power supply. In this case the internal power supply is such that there is both a primary and further power supply within the portable device, this on-board power supply redundancy allows for the system to be powered reliably while not being connected to an external power supply such as the mains.

In some embodiments, said portable vacuum pump assembly comprises an interface for connection to an external power supply; wherein said power control circuitry is configured to maintain a continuous power supply to said vacuum pump by: during a period that said interface of said vacuum pump assembly is connected to said external power supply routing power to said vacuum pump from said external power supply; and during a period that said interface of said vacuum pump assembly is not connected to said external power supply routing power to said vacuum pump from said internal power supply.

The portable vacuum assembly may have an interface for connection to an external power supply. The power control circuitry is configured in such a case to route power from the external power supply to the pump when the external power supply is connected to the assembly, and when not to route power from the internal power supply. When connected to the external power supply power may also be routed to recharge the internal power supply. In this way a pump assembly can be used connected to an external power source and then when such a source is no longer available it may be powered by the internal supply. In this way the assembly may for example be moved between external power supplies, perhaps between rooms in a hospital, or it may be moved in a vehicle and powered by a battery within the vehicle and then powered by the internal supply when leaving the vehicle to a site the vehicle cannot access. It also allows it to be used in remote locations where no external power supply is available.

In some embodiments, said primary power supply comprises a main power supply and said further power supply comprises a back up power supply.

The further power supply may be significantly smaller than the first power supply and act as a back up power supply to power the vacuum pump assembly for much of the time. The back up power supply may be used when the main power supply is running low on charge to avoid a power interruption and provide some time for the main power supply to be replaced with anew main power supply.

For example, in some embodiments said primary power supply is configured to supply power for operation of said vacuum pump for at least one hour and said further power supply is configured to supply power for up to 25% of an operation time of said main power supply, preferably less than 10%.

In some embodiments, said primary and further power supply are rechargeable power supplies and said internal power supply is configured such that said further power supply is recharged by said primary power supply and said primary power supply and further power supply are recharged by said external power supply when said vacuum pump assembly is connected thereto.

In some embodiments, said further power supply is sized to provide power to said vacuum pump for a time period estimated to be longer than a time period required to change said primary power supply for a replacement power supply and less than ten times, preferably less than three times as long as said estimated time period. One way of providing an effective reliable and continuous power supply is to provide a further power supply of a capacity sufficient to power the vacuum pump while the primary or main power supply is changed. This allows the amount of power supply resource to be selected depending on a particular deployment of the portable vacuum system. Thus, one or more additional primary power supplies or batteries may be taken with the system depending on the location and estimated length of time that the system is to be used for. Where several spare primary batteries are taken and several changes of battery made, it may be advantageous if the further battery is rechargeable and recharged by the primary battery. In his way the further battery will be able to power the system through any number of battery changes.

In other embodiments, said primary power supply and said further power supply have a similar capacity and are both configured to be removable from said internal power supply. Power supplies are considered to have a similar capacity when their capacity is within 20% of each other.

In order for the power control circuitry to provide effective control of the internal power supply it should be able to predict accurately when the primary power supply is about to fail to provide sufficient power for the pump either due to a reduction in charge or due to being removed by the user. This may be done in one or more of the following ways: detecting a level of charge of said primary power supply falling below a determined level; detecting activation of a power supply release button; and detecting a user input indicating a power supply change is to be initiated.

In some embodiments, in response to said power control circuitry detecting a level of charge of said primary power supply falling below said predetermined level, said power control circuitry is configured to route power to said vacuum pump from said further power supply and to operate said vacuum pump in a lower power mode. One further way of providing a reliable power supply is to switch to a low power mode when the primary power supply’s charge levels are depleted. This allows the vacuum operation of the pump to be maintained for longer albeit in a reduced lower vacuum or lower throughput state. This additional operating time may be sufficient for the system to be returned to an external power supply or for the main power supply to be changed.

In some embodiments, said vacuum pump assembly comprises a receiving interface for connecting with a connecting interface of said primary power supply, and said primary power supply comprises at least one power supply comprising said connecting interface for connecting to said receiving interface of said vacuum pump assembly and a further receiving interface corresponding to said receiving interface of said vacuum pump assembly.

The primary battery may be configured as a stackable battery with for example, a plug arrangement on one side and a socket arrangement on the other. Such, a battery may be connected to the vacuum pump assembly which has a

corresponding plug or socket, and to one or more other similar batteries. Such an arrangement allows the batteries to be stacked. When stacked their terminals are connected such that they are electrically connected in parallel. In this way the capacity of the battery can be varied and selected depending on deployment. This allows either one battery or a stack of a selected number of batteries to be deployed as the primary battery powering the system.

In some embodiments, the vacuum pump assembly further comprises pump control circuity for controlling operation of said vacuum pump, said power control circuitry being configured to supply power to said pump control circuitry.

In some embodiments, the assembly comprises a plurality of vacuum pumps, one of said vacuum pumps comprising a turbo pump and a further one of said pumps comprising a backing pump for said turbo pump. ln some embodiments said backing pump comprises a scroll pump.

As noted previously it may be disadvantageous if power is suddenly removed from a vacuum pump assembly. This is particularly so for systems comprising a turbomolecular pump backed by another pump. Many turbomolecular pumps require a low pressure at their exhaust to function effectively. A sudden increase in pressure at the exhaust of such a pump due to the backing pump stopping suddenly can lead to a sudden large pressure difference across the

turbomolecular pump. The rotor of the turbomolecular pump is spinning at high speed, the forces on the rotor due to a sudden increase in pressure may cause it to break or be damaged in some way as well as the vacuum being lost at the inlet.

In some embodiments, said control circuity is configured to control said plurality of pumps.

The control circuitry that is used to control the powering of the pumps may also be used to control the operation of one or more of the pumps.

In some embodiments, the portable vacuum assembly further comprises a display configured to display an indication of a remaining charge of at least one of said primary and further power supply.

The display may indicate this, by displaying some kind of indication such as a red, green or amber light, or by displaying a number indicative of an amount of charge or an estimated remaining time of operation.

In some embodiments, the vacuum pump assembly comprises an output for outputting towards a remote device an indication of at least one of a remaining charge and an estimated remaining time of operation of at least one of said primary and further power supply. The control circuitry determines the remaining charge of the battery and in some embodiments, outputs an indication of this to a remote device. This information may be output in the form of a wireless communication signal such that the remote device, perhaps a smart phone or tablet can receive this information and provide remote monitoring of the vacuum pump assembly. The control circuitry may have a charge sensor or detector to determine the amount of charge, or it may determine this in another way, such as from a determination of the time of operation since the previous charging cycle.

In some embodiments, said portable vacuum assembly comprises a notification indicator configured to indicate that a charge of said further power supply has dropped below a predetermined value. The notification indicator may be one or more of an alarm, a warning light or signal, or an audible alarm signal. In this regard a notification warning may be sent at one power level and an alarm at a later lower level.

In some embodiments, said power control circuitry comprises circuitry configured to detect when said interface is disconnected from said external power supply and to determine at least one of a distance or time during which said portable vacuum assembly moves when disconnected from said external power supply; said power control circuitry comprising an indicator configured to indicate when a charge of said batteries of said internal power supply falls close to a

predetermined level of charge determined to be sufficient to power said vacuum pump during a time estimated to be required for said portable vacuum pump assembly to return to said external power supply.

Where the portable device moves away form an external power supply in use, then it may be convenient to provide some sort of monitoring system that relates remaining charge to estimated distance/time to the external power supply. This allows the system to signal to a user when it may be advisable to return to the external power supply before the internal power supply becomes exhausted. ln some embodiments, said indicator comprises an alert indicator and said indicator is configured to indicate an alert when said charge is detected as falling to within 20% of said predetermined level of charge.

A second aspect provides a portable mass spectrometer or other vacuum equipment comprising a portable vacuum pump assembly according to a first aspect.

In some embodiments, the mass spectrometer or other vacuum equipment and vacuum pump assembly are powered from the same internal power supply, said power control circuitry being configured to power said mass spectrometer by routing power from said internal power supply when said vacuum pump assembly is not connected to an external power supply.

Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which:

Figure 1 shows a mass spectrometer and portable vacuum system according to an embodiment;

Figure 2a shows a portable vacuum system according to a further embodiment; Figure 2b shows a portable vacuum system according to a still further

embodiment; and Figure 3 shows a method of controlling a power supply supplying a portable vacuum system according to an embodiment.

DESCRIPTION OF THE EMBODIMENTS

Before discussing the embodiments in any more detail, first an overview will be provided.

Embodiments seek to enable continuous (and extended) operation of a point of use internally powered vacuum system by means of hot-swapping the batteries or other internal power supply before they expire in a way that ensures the vacuum is maintained.

The principle is to provide a power supply capability which enables the power supply to be changed (replaced) without loss of vacuum. In a typical portable vacuum system there may exist a primary and a secondary vacuum pump combination (e.g. a turbomolecular pump and a diaphragm pump). These pumps are typically designed as miniaturised solutions optimised for low power consumption and small dimensions to enable appropriate levels of performance with maximum power supply life.

The concept is known of continuous operation by running such a system from an external power supply (mains or external battery e.g. car) until the portability is required. The system is then removed from the external supply and operates under its on-board power supply whilst it is‘deployed’. It may then be returned to the same or different external supply once the deployment is finished. The amount of time the vacuum system assembly is operable away from the external supply depends upon (partly) the internal power supply capacity and so for longer deployments a larger heavier power supply is required. Embodiments seek to reduce the size of the internal power supply whilst enabling hot swapping of the power supplies to offer uninterrupted extended operation of the vacuum system. In a system without such a capability, removal of the power even for a very short time (~1 sec) could cause major loss of vacuum performance. This is due to the high pressure difference across the primary pump which could cause it to slow down quickly resulting in high backing pressure in the turbo and major system performance loss and potential damage to the turbo. One potential solution is to valve the inlet and outlet of the turbo such that it remains running under its inertia whilst the battery is changed but this means the vacuum system is not functioning fully during that period and it also adds of cost, weight and control complexity (ensuring the valves are closed) to the system.

Embodiments provide an alternative improved solution that has two on board power supplies- only one of which is being used to operate the system at a time. The functioning power supply can be switched over to enable a change of the other power supply keeping the system running.

In a first embodiment, two internal power supplies are provided one of them being considerably smaller than the other and fixed inside the equipment. This is the ‘back up’ power supply and is only ever used when the main power supply is being changed over (or when the main power supply runs out). In this way it can be small in size and capacity. The main power supply is therefore the one which the user interacts with, charges, changes etc. For example, the back-up power supply could be 1 /10th the capacity of the main power supply and embedded in the product - potentially PCB mounted on the controller. Having the backup battery as a fixed unit also allows it to be smaller as it obviates the need for connecting means. Furthermore, it is not required to be mounted in an accessible position.

The back up power supply is charged when the system is connected to an external source. The capacity of it is sized to enable an‘appropriate number’ of power supply swaps depending on implementation. Alternatively, the back up power supply may be able to be charged by the main power supply meaning that each time a power supply swap takes place the back up power supply recharges quickly off the main power supply which has just been inserted. This method enables an even smaller backup power supply device to be used based on the requirements of a single hot swap. It should be noted that the power supply may be a battery where the energy is stored chemically, or it may have another form such as a supercapacitor where the energy is stored electrically. The system may be such that the main and back up power supply have different forms.

One feature of a hot swap may be that the switchover between the main and back up power supplies is automated based on detection of power level remaining in the main power supply.

Alternatively or additionally there may be a button is pressed by the user to alert the system that a hot swap is about to take place and the system then switches over to the back up power supply before the main power supply is removed. This button which is pressed by the user may also act as the power supply release such that it is not possible to disconnect the power without the system switching source.

In a further embodiment both power supplies may be detachable and in some embodiments they may be of a similar size enabling the user to choose how to use them and their size, depending on a power supply life requirement.

In some embodiments the system contains a display (audio and / or visual) of battery status. This could be a simply RAG (re amber green) indicator or it may be a quantified amount. The amount could be stated in RUL (remaining useful life) time or % etc. This could be for either or both power supplies. In one embodiment, the user would not‘know’ about the back up power supply and in this case the status would only appear as an‘Alarm’ if there was a problem. In almost all cases the main power supply charge would be visible.

In some embodiments the alarm (audio and / or visual) would sound if one of the power supply levels falls below a specified level eg 20%. This level could be user configurable. This may be the main power supply level or in some cases where the power supplies are of a similar size it may be the second power supply level.

If the level is for the main battery or power supply and the power continues to fall to a level which can’t sustain operation then the back up battery or power supply can be invoked as a last resort to extend life. This can also be combined with a reduced energy operating condition such as idle mode or reduced performance mode to extend the life of either battery.

The size / capacity of the main power supply may be selected by the user for a particular deployment. In some cases different capacity devices are configured with the same interfaces, the higher capacity devices being larger and extending away from the system.

In some embodiments, it may be possible to‘stack’ batteries such that a user can get double the operating time, for example, by stacking two batteries (rather than having a battery twice as big). In this case each battery has both a‘plug’ and a ‘socket’. Internal control electronics would manage the voltage / current etc, as well as manging the warning and alarm limits according to the total capacity installed.

The battery device may be used in combination with a single or multiple control boards which may control more than one vacuum pump or motor.

In some embodiments, the control board and base charging stations employ a GPS chip to detect‘distance to charge’ and derive a‘time to base station’ based on‘walking’ or on detected speed and provide alerts if the remaining battery run time falls close to this‘time to base station’ to alert the user.

Figure 1 shows a mass spectrometer 5 according to an embodiment. Mass spectrometer 5 comprises vacuum chambers 10 evacuated by a portable vacuum system 20 according to an embodiment. Portable vacuum system 20 comprises a turbo molecular pump 22 backed by a scroll pump 24. The vacuum pumps 22, 24 are powered by an internal power supply 30 which in this embodiment comprises a main battery 32 and a back-up battery 34. These batteries power one or more motors 40 which drive the two vacuum pumps. Power control circuitry 50 controls the supply of power from the two batteries to the motor, via in this embodiment switching circuitry 52.

In this embodiment, initially motor 40 is powered by main battery 32, control circuitry 50 routing the power from this battery to the motor 40 via switching circuitry 52. When the control circuitry 50 detects that the level of charge in battery 32 is dropping below a predetermined level, which level may lead to compromised performance within a certain time period, then control circuitry 50 may alert user to this by triggering an alarm 60. Alarm 60 in this embodiment comprises a loudspeaker that emits an audible signal.

If the user ignores this signal and continues to use the device then when the amount of remaining charge in battery 32 falls to a further level where powering of the motor 40 may be compromised then the control circuitry switches the supply of power from battery 32 to battery 34 such that battery 34 now powers the motor 40 driving vacuum pumps 22 and 24. At this point, the pumps may be switched to a low power mode of operation and a further indicator 62 is

illuminated indicating to the user that the backup battery 34 is now in use and that the main battery 32 can be removed from the system and exchanged for a new battery. In this way, the batteries may be exchanged and the system continue to run uninterrupted.

When a new battery is inserted into the system then the control circuitry 50 can control the supply of power to once more come from the main battery 32 and the pumps may be switched from low power mode to normal operating mode.

Control circuitry 50 can also control switching circuitry 52 to route power from battery 32 to recharge battery 34, thus allowing it to be fully charged when the new battery 32 runs down to a level that requires it to be exchanged for a new battery.

In the event that the battery 34 depletes below a predetermined level and in the absence of sufficient charge in battery 32, the vacuum system may issue another alarm and go into an auto shutdown procedure whereby the vacuum system is safely brought to a stop in a way which does not do damage to the individual pumps. This may also involve the isolation of parts of the vacuum system using valves controlled by the control circuitry.

In this way, a portable system is provided that can provide continuous operation provided that a user has a suitable number of spare batteries. The ability to switch batteries allows the vacuum system to have a reduced size and yet have the ability to provide prolonged use if required.

It should be noted that the control circuitry 50 which controls the powering and operation of the vacuum pumps, may in some cases also control powering and operation of the mass spectrometer or other vacuum system equipment.

Figure 2a shows a portable vacuum system according to a further embodiment. This portable vacuum system is configured to connect to an external power supply 70. In this regard, the system may be adapted for use in a hospital for example where it can be disconnected from the power supply 70 and wheeled between different points of use or it may be adapted for use in remote sites where it is connected to a power supply 70 on a vehicle, for example, and disconnected from that when it is used in the field remote from the vehicle.

In this embodiment control circuitry 50 is configured to determine when the system is connected to the external power supply 70 and to control the supply of power to the motor or motors 40 driving the pumps 20 from this external power supply 70. The control circuitry 50 detects when the system is disconnected from the external power supply 70 and at this point controls the power to be supplied from the batteries 30. In this embodiment the batteries 30 comprise a stack of similarly sized batteries 32 with interfaces 36 and 37. Interface 36 comprises a plug type interface which is adapted to fit into a socket 37 on the corresponding face of the battery. Furthermore, the external power supply 70 has a

corresponding socket interface 37 to which the batteries may be connected when connected to this power supply. In this way, a portable device with a required number of batteries may be provided, the batteries being stacked according to the particular deployment. When stacked together the batteries 32a, 32b are electrically connected in parallel. In some embodiments in addition to a stack of similar batteries with corresponding interfaces the battery supply 30 may also comprise a smaller backup battery 34. In this case, the power control unit will determine when the charge of the stack of batteries is falling below a limit value and will switch the power supply to the backup battery 34. This will allow the stack of batteries to be changed if required while maintaining operation of the pump system. In this regard, the control circuitry may switch the vacuum pump to low power mode at this time to prolong its operation on the smaller battery.

In this embodiment, all of the batteries are re-chargeable batteries and when they are plugged into the external power supply 70 control circuitry 50 routes the power from the external power supply 70 not only to powering the vacuum pumps but also to re-charging the batteries.

In some embodiments, the control device 50 may have a means of monitoring a time and distance of the portable device from the external power supply and may be configured to determine when the remaining charge of the batteries 32a, 32b drops to a level below which the system may not be able to continue operating during the time it will take to return to the external power supply 70. At this point a signal may be sent to the user indicating that if no further spare batteries are available then the device should be returned to the external power supply 70.

This will help avoid a situation where the system runs out of power and continuous operation is no longer possible. Figure 2b shows an alternative embodiment to that of Figure 2a with a slightly different configuration. In this embodiment the batteries 32a, 32b connect directly to the vacuum system to power it and the external power supply 70 connects separately to the vacuum system. There is a link via control circuitry 50 between the external power supply and the batteries 32a, 32b allowing the batteries to be recharged when the external power supply is connected to the system.

Figure 3 shows a flow diagram illustrating steps in a method performed by the power control circuitry 50 of Figures 2a and 2b. Power control circuitry 50 has monitoring logic for determining whether or not the external power is currently connected to the portable device. If it determines that the external power supply is currently connected then it routes power to the motor driving the pumps from the external power system. It may also route power from the external power supply to recharge the batteries of the internal power supply where it determines that they are not fully charged.

If the monitoring logic determines that the external power supply is not currently connected then it will route power to the motor from the internal power supply. It will preferentially route power from the main battery 32 unless it determines the main battery 32 to be below the required charge level. Thus, it determines whether the charge of the main battery is below a predetermined level. If it determines it is above this level then it will route power from the main battery to the pumps. If it determines that it is below this level then it will switch power to the backup battery and it will illuminate a light indicating that the main battery is to be changed. In some cases it may also switch the mode of operation of the pumps to low power mode. In some embodiments low power mode may be invoked prior to use of the backup battery when the charge of the main battery is detected to fall below a first predetermined level, switching to the backup battery occurring later at a lower predetermined charge level.

The control circuitry will monitor the charge level of the main battery and when it rises above a predetermined level which will occur if it is changed for a new battery then it will re-route power from the main battery to the motor again. It will also route power from the main battery to charge the backup battery, such that the backup battery is fully charged when/if the main battery needs to be changed again.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

REFERENCE SIGNS

5 portable mass spectrometer

10 vacuum system

20 vacuum pumps

22 turbo pump

24 backing pump

30 internal power supply

32, 32a, 32b main battery

34 back-up battery

36 plug interface

37 socket interface

40 motor

50 control circuitry

52 switching circuitry

60 audible alarm

62 visual alarm

70 external power supply