Reducing power consumption in vacuum pump

Abstract

A vacuum pump and a method of controlling such a pump to reduce power consumption of the pump during a standby mode. The method comprises: operating the pump by driving the pumping mechanism at a rated speed; determining that the pump will enter a standby mode in which an exhaust check valve is closed; increasing the speed of the pumping mechanism for a predetermined time to reduce the amount of gas within the pump; and reducing the speed of the pumping mechanism and operating the pump in the standby mode with the exhaust check valve closed.

Description

Technical Field

[0001] The present invention relates to vacuum pumps, and to the control of these pumps to reduce power consumption, particularly in steady-state standby mode. Background Technology

[0002] In mechanical vacuum pumps (such as positive displacement vacuum pumps), total power consumption is a combination of useful power (used for moving and / or compressing gas) and losses. Losses are primarily related to electrical and magnetic efficiencies (motor and drive) as well as parasitic losses (gas leakage, cooling fan, friction). Clearly, there is potential to reduce losses through design improvements, but the power used for gas movement and / or compression is more difficult to reduce.

[0003] In many applications, whether evacuating chambers or pumping a steady gas flow at low pressure, vacuum pumps typically spend at least part of their operating time maintaining a vacuum and operating with very little or no gas throughput. During this mode, the exhaust check valve is usually closed. 'Green' or 'standby' modes exist, and they typically involve a reduction in rotational speed to reduce frictional losses (power = torque × angular velocity, and torque includes bearing frictional losses). The reduced speed results in a different pressure distribution and higher ultimate pressure, and the power reduction may be rather limited, especially compared to optimal savings (i.e., completely shutting off the pump).

[0004] The goal is to reduce the power consumption of the vacuum pump, especially when operating in standby mode, where there is very little or no gas throughput most of the time and the pump may be pumping at or near its limit pressure. Summary of the Invention

[0005] A first aspect provides a method for controlling a mechanical vacuum pump to reduce power consumption of the pump during a standby mode, the method comprising: operating the pump by driving a pumping mechanism at a rated speed; determining that the pump will enter a standby mode in which an exhaust check valve is closed; increasing the speed of the pumping mechanism for a predetermined time to reduce the amount of gas in the pump; and decreasing the speed of the pumping mechanism and operating the pump in the standby mode with the exhaust check valve closed.

[0006] Many mechanical pumps that operate as the main pump and exhaust gas to the atmosphere (such as positive displacement pumps) have check valves that mitigate the effects of failure modes and prevent the pump from returning to atmospheric pressure for short periods. They also improve pump efficiency by closing the valve during steady-state operation with no gas flow. This mode, where the valve remains closed for a period and there is very little or no gas flow, can be called a standby mode, during which the pump simply maintains a vacuum in the pumped space.

[0007] It is recognized that when the check valve is closed and the pump is operating only to maintain the pressure within the pumped chamber, the gas within the pump is moved and / or compressed and then expands again with each cycle. This consumes energy. It is also recognized that if the amount of gas within the pump is reduced during standby mode, the amount of energy required to supply this periodic movement and / or compression of the gas within the pump will be reduced. Therefore, the present invention provides a speed boost to the pump before entering or during this standby mode, such that the amount of gas within the pump is reduced and the energy required for the periodic movement and / or compression of the gas within the pump in this mode is correspondingly reduced. The power required for the speed boost increases somewhat, and the speed boost will increase wear on pump components such as bearings; however, the speed boost only requires a short period of time, thus saving overall power.

[0008] In this way, the embodiments provide a method to achieve significant power savings without compromising pump inlet pressure when operating with no or very low gas throughput.

[0009] In some embodiments, the step of increasing the speed of the pumping mechanism includes increasing the rotational speed of the motor driving the pumping mechanism.

[0010] By increasing the speed of the pumping mechanism, the pump's volumetric capacity and, in some cases, the pump's compression increase, while the amount of gas inside the pump decreases.

[0011] In some embodiments, the predetermined time is greater than 1 second, preferably greater than 3 seconds, and in some cases greater than 5 seconds.

[0012] In some embodiments, the predetermined time is less than 120 seconds, preferably less than 60 seconds.

[0013] In some embodiments, the increase in rotational speed includes an increase of more than 5% of the rated rotational speed, preferably more than 10% of the rated speed.

[0014] In some embodiments, the step of reducing the speed of the pumping mechanism includes reducing the speed to the rated speed.

[0015] In other embodiments, the step of reducing the speed of the pumping mechanism includes reducing the speed to a rate of reduction below the rated speed.

[0016] In some embodiments, the lower speed is more than 10% lower than the rated speed.

[0017] In the standby mode where the exhaust check valve is closed, it is acceptable to operate the pump at a speed lower than the rated speed, thereby reducing power consumption.

[0018] In some embodiments, the step of determining that the pump will enter standby mode includes at least one of the following: receiving a control signal from a user, receiving a control signal from a vacuum system associated with the pump, and receiving a control signal from at least one sensor.

[0019] The determination that the pump will enter standby mode can be made in response to signals received from the user or control signals from the vacuum system indicating that the pump is evacuating and / or control signals from sensors associated with the pump or vacuum system.

[0020] The sensor may be a power sensor that senses the power of the pump's motor or, if the pump supports a secondary pump, the power of the secondary pump's motor.

[0021] Alternatively and / or additionally, it may originate from a pressure sensor that senses pressure in the sensing chamber or pressure within the pump or elsewhere in the associated vacuum system, and / or from a sensor that indicates the exhaust check valve has closed and has remained closed for a predetermined time. Signals from the vacuum system may originate from a control system that controls the vacuum system and / or the pump.

[0022] In some embodiments, the step of determining that the pump will enter a standby mode includes receiving a control signal from at least one sensor that senses the power consumption of the motor, the sensor indicating that the power consumption is at or near a value indicating low gas throughput or zero gas throughput, and the method further includes the steps of: determining the rate of increase of power consumption after the step of reducing the speed of the pumping mechanism, and exiting the standby mode when the rate of increase of power consumption is greater than a predetermined rate.

[0023] In cases where entering standby mode is triggered by detecting the pump's power consumption at or near a value indicating no gas throughput, it is possible to perform additional steps once in low-power mode to verify that the pump has indeed reached the no-gas-throughput condition. This additional step monitors the rate of increase in power consumption, and if this rate is higher than expected and exceeds a threshold, it provides an accurate indication that the pump has not reached zero gas throughput. In this case, the pump can exit low-power mode and resume normal operation. In practice, pump power consumption at low gas throughput is dominated by mechanical losses, making accurate detection of no gas throughput challenging. However, once in low-power mode, power sensors can accurately detect the presence of gas throughput because the increase in power consumption will be relatively rapid. Therefore, providing this additional check allows for shutting down low-power mode when appropriate. Since the power boost is relatively short and provides power savings afterward in any case, this trial-and-error approach has few drawbacks and can provide effective power savings.

[0024] In some embodiments, the method includes the following additional steps performed during the standby mode: determining that the amount of gas in the pump needs to be reduced; increasing the rotational speed of the pump for a predetermined time to reduce the amount of gas in the pump; and reducing the rotational speed and returning to operation in the standby mode.

[0025] During standby mode, the amount of gas inside the pump may gradually increase due to gas leakage into the pump, and in some cases, the method may include determining this situation and responding by re-enforcing the boost speed to reduce the amount of gas inside the pump. In this way, even with a small amount of airflow (possibly due to leakage into the system), the amount of gas inside the pump can remain at a low level for an extended period.

[0026] In some embodiments, the determining step includes at least one of the following: determining that the power consumption of the pump or a secondary pump in the same system has increased by a predetermined amount or to a predetermined amount; determining that the pressure has increased by a predetermined amount or to a predetermined amount; determining that a predetermined time has elapsed since the last increase in speed; or determining that a signal has been received from the operator or the vacuum system.

[0027] The determination that the amount of gas in the pump has increased and should decrease can be made by monitoring an increase in the power consumption of the pump or a secondary pump in the same system, and / or an increase in the inlet pressure, and / or by monitoring the time elapsed since the last boost and / or by receiving signals from the operator or control system.

[0028] In some embodiments, the determining step includes determining that the pressure inside the pump, or in the pumped chamber, or in an associated vacuum system, has increased by a predetermined amount.

[0029] In some embodiments, the method further includes determining the frequency at which the boost is repeated during the standby mode, and outputting a warning indication to the operator in response to determining that the frequency has increased beyond a predetermined threshold amount.

[0030] The frequency at which the speed needs to be increased in standby mode is an indication of leakage into the pump or vacuum system, and therefore, may be an indication of a system malfunction. Thus, in some cases, monitoring this frequency and seeing it rise above a predetermined level can be used as an indication of a system malfunction.

[0031] On the other hand, a computer program is provided, including computer-readable instructions that, when executed by a processor of a controller of a mechanical vacuum pump, are configured to control the pump to perform according to one aspect of the method.

[0032] In some embodiments, the computer program is stored on a non-transitory computer-readable medium.

[0033] In some embodiments, the computer program includes a PID (proportional-integral-derivative) control loop that adjusts the system response to the size of the system being evacuated and provides a slower, smoother response for larger systems.

[0034] In some embodiments, the control loop is configured to determine the predetermined time for increasing the pump speed based on the size of the system being evacuated. In some embodiments, the predetermined time is greater than 1 second, preferably greater than 3 seconds, and in some cases greater than 5 seconds. In some embodiments, the predetermined time is less than 120 seconds, preferably less than 60 seconds.

[0035] The pump can be used to evacuate different systems that may have different sizes. The amount of time the pump speed should be increased may depend on the system being evacuated; larger systems may require a longer time, and in some embodiments, the computer program in the pump controller may have a PID control loop operable to adjust the pump to reflect the size of the system being evacuated and to provide an appropriate boost period.

[0036] Another aspect provides a controller for a mechanical vacuum pump, the controller comprising: a control circuit configured to control the speed of the pumping mechanism of the pump, the control circuit being configured to: control the pump such that the pumping mechanism is driven at a rated speed; and in response to receiving a signal indicating that the pump will enter a standby mode, in the standby mode the exhaust check valve is closed to control the pump to increase the speed of the pumping mechanism for a predetermined time to reduce the amount of gas in the pump; and after the predetermined time, reducing the speed of the pumping mechanism and continuing to drive the pumping mechanism in the standby mode with the exhaust check valve closed.

[0037] In some embodiments, the step of reducing the speed of the pumping mechanism includes reducing the speed to the rated speed.

[0038] In some embodiments, the step of reducing the speed of the pumping mechanism includes reducing the speed of the pumping mechanism to a low-power speed below the rated speed.

[0039] In some embodiments, the signal is received from at least one of the following: a user, a control system, or a sensor.

[0040] In some embodiments, the sensor may be a power sensor, a pressure sensor, or a sensor that indicates that the valve has been closed and remains closed for a predetermined time.

[0041] In some embodiments, the sensor is a power sensor, which is further configured to determine the rate of increase in power consumption after the pumping mechanism reduces the speed, and in response to the rate of increase in power consumption being greater than a predetermined level, the control circuit is configured to control the vacuum pump to exit the standby mode.

[0042] In some embodiments, the control circuit is further configured to, in response to receiving a signal during a standby mode indicating that the amount of gas in the pump needs to be reduced; control the motor to increase the rotational speed of the pump for a predetermined time to reduce the amount of gas in the pump; and after the predetermined time, reduce the speed of the pumping mechanism and return to controlling the pump to operate in the standby mode.

[0043] In some embodiments, the signal is generated in response to at least one of the following: the power consumption of the pump increases by a predetermined amount or to a predetermined amount; the pressure at the pump inlet increases by a predetermined amount or to a predetermined amount; a predetermined time has elapsed since the last increase in speed; or input from an operator or control system.

[0044] On the other hand, a mechanical vacuum pump is provided, comprising: The motor used to drive the pump; Check valve; and According to another aspect, the controller is used to control the operation of the mechanical vacuum pump.

[0045] In some embodiments, the pump includes at least one sensor for sensing pressure at the inlet, or a sensor for sensing motor power consumption, and / or a sensor for sensing time elapsed since the last speed increase.

[0046] In some embodiments, the mechanical vacuum pump includes either a positive displacement vacuum pump or a regenerative vacuum pump.

[0047] In some embodiments, the positive displacement pump includes a dry positive displacement pump.

[0048] In some embodiments, the positive displacement pump includes one of a scroll pump, a multistage roots pump, a screw pump, a claw pump, a diaphragm pump, a reciprocating piston pump, or a rotary vane pump.

[0049] In some embodiments, the vacuum pump includes a port screw pump.

[0050] Vacuum pumps according to embodiments with a check valve located close to the pump offer particularly effective power reduction because the reduction in the amount of gas inside the pump due to the increased speed of the pump mechanism increases with the reduction in the gas volume between the valve and the pump. Port pumps (such as port screw pumps) have a valve at the port at the pump's exhaust port, thus having a very small volume between the valve and the pump.

[0051] It should be noted that some vacuum pumps may contain impurities such as liquids and particles in their exhaust gas flow, which can clog the exhaust valve. One way to mitigate this problem is to provide pump exhaust into the gas collection chamber, which protects the valve from impurities, but the increased volume between the pump and the valve reduces the power reduction achieved by increasing speed. Dry pumps do not require such valve protection, allowing the valve to be placed closer to the pump. Vortex pumps are typically equipped with a check exhaust valve near the pump outlet, and embodiments of these pumps provide particularly effective power reduction.

[0052] In some embodiments, the vacuum pump includes a regenerative vacuum pump, and in some embodiments, the vacuum pump includes a side-channel blower.

[0053] The power consumption of a regenerative vacuum pump depends on the amount of gas circulating inside the pump, and therefore, in a similar manner to a positive displacement pump, the reduced amount of gas inside the pump when the pump is operating with the exhaust valve closed and at essentially zero throughput reduces the pump's power consumption.

[0054] Another aspect provides a vacuum system including a vacuum pump according to another aspect, the vacuum pump including a main vacuum pump and the vacuum system further including a secondary vacuum pump including an inlet valve, the controller being configured to close the inlet valve in response to receiving a signal indicating that the pump will enter a standby mode.

[0055] In a vacuum system comprising multiple pumps, power consumption can be further reduced if the gas volume within both the secondary and primary vacuum pumps decreases during operation at essentially zero throughput. This can be achieved by closing the inlet of the secondary vacuum pump when the ultimate pressure is reached (before, during, or immediately after increasing the speed of the primary pump). Immediately afterward, this could be within 5 seconds, preferably within 1 second, after the speed increase is complete. In this case, a sensor sensing the vacuum chamber being pumped may be needed to indicate to the controller that the pressure in the vacuum chamber is rising, allowing the valve to be opened and the pump system to become operational again.

[0056] Further specific and preferred aspects are set forth in the appended independent and dependent claims. Features of the dependent claims may be suitably combined with features of the independent claims, and may be combined in combinations other than those expressly set forth in the claims.

[0057] The device features are described as being operable to provide functionality, and it should be understood that this includes device features that provide the functionality or are adapted or configured to provide the functionality. Attached Figure Description

[0058] Embodiments of the present invention will now be further described with reference to the accompanying drawings, wherein: Figure 1 A vortex pump and controller according to an embodiment are shown; Figure 2A and 2B The pressure distribution within a pump with and without increased rotational speed is schematically shown. Figure 3 A flowchart illustrating the steps in a method according to an embodiment is shown; and Figure 4 This illustrates how the power consumption of the vacuum pump according to an embodiment changes over time; and Figure 5 A side-channel blower according to an embodiment is shown. Detailed Implementation

[0059] Before discussing the embodiments in more detail, an overview will be provided first.

[0060] Positive displacement pumps, such as scroll vacuum pumps, typically have a check valve at the outlet to prevent atmospheric ingress. This valve closes via a low-speed spring, and its primary function is to prevent downstream gas from flowing back into the user's system when the scroll pump stops, thus maintaining vacuum even in the event of a power failure. An isolation valve at the pump inlet is an alternative, but it is more expensive and introduces gas flow restriction.

[0061] During steady-state operation with no or very low gas throughput, this check valve is closed. The pump contains a limited amount of gas to be retained, and under these extreme conditions, the gas compression power is consumed to maintain the pressure gradient between the inlet and outlet. Most of the gas is in the final stage, where the pressure is close to atmospheric pressure.

[0062] If the trapped gas in the final stage can be discharged or isolated, the steady-state power requirement will be reduced.

[0063] The embodiment provides a solution in which the pump can briefly operate at a rotational speed higher than its normal rated speed (to improve performance and expel some extra gas) when the gas throughput is essentially zero, and then return to the normal speed or a lower standby speed to take advantage of the reduced gas load.

[0064] When the pump operates without gas throughput, it reaches a steady state. The gas within the pumping mechanism is distributed according to the pump's compression characteristics. The check valve at the outlet no longer opens because the pressure in the final stage is insufficient to overcome the valve spring.

[0065] If the pump's rotational speed is increased, its ability to resist backflow improves and the pressure distribution becomes more biased towards the outlet. The pressure in the final stage is sufficient to open the valve and allow more gas to be expelled from the pump. After a short period, the pump is able to return to its rated speed – now with lower power requirements because the pressure in the final stage has been reduced. (Note that while continuous operation at higher speeds will improve the pump's overall performance, the increased load on the bearings will be detrimental in the long run.)

[0066] If the pressure in the final stage has been reduced, the internal leakage rate through the other stages will also decrease, and a low limiting pressure may be maintained even if the pump speed is reduced below its rated value to allow for further power savings. Note that such pumps typically already have an optional 'standby' speed reduction capability, but this results in an increase in inlet pressure. The embodiments are designed to provide reduced power without compromising vacuum performance; if the reduced performance is practically acceptable, a preferred way to conserve power may be to slow down or stop the pump entirely.

[0067] In some embodiments, an existing pump can be retrofitted with suitable control circuitry that enables the pump to cycle through the sequence once the gas throughput decreases to zero or near zero. This allows for higher-speed operation for short periods (perhaps only 30 seconds). This process can be manually controlled or it can be automated. To automate this process, the pump should recognize no-flow conditions. If this is done using a power sensor, it can be challenging because power consumption at zero throughput is similar to that at low gas throughput, as it is dominated by mechanical losses. In some embodiments, this is addressed by initiating a boost cycle and a low-power standby mode once power consumption has dropped to a certain value, in some cases only under the additional condition that the standby mode has been inactive for a predetermined time. The rate of increase in power consumption is then checked to determine if it is greater than expected, and if so, this indicates the presence of gas throughput, and therefore, invoking power saving is inappropriate. In this case, the pump is controlled to exit the power-saving mode. The threshold indicating the rate of increase in gas throughput will depend on the type and size of the pump and the system that may be being pumped, and will be configured for the specific pump and setup.

[0068] Figure 1A vortex pump 30 according to an embodiment is shown. The vortex pump 30 includes an exhaust check valve 20, which may be a spring-loaded valve configured to open under differential pressure and close when the pressure at the pump outlet is below atmospheric pressure. In this way, the pump can be sealed when the pump is no longer pumping gas, which may be when the pressure at the inlet has reached a limit pressure. The vortex pump 30 has a motor 10 for driving the vortex pump and a controller 40 for controlling the operation of the motor. There is also a sensor 42, which in this embodiment is associated with the motor 10 for sensing the power consumption of the motor. During operation, the controller 40 controls the motor 10 to drive the vortex pump to evacuate the chamber, and when a steady state is reached, which may be at the limit pressure at the inlet, the valve 20 closes and the sensor 42 indicates that this state has been reached, and the controller 40 receives a signal from the sensor 42 indicating that the pump will enter a standby mode. At this time, the controller 40 increases the operating speed of the motor 10 from its rated rotational speed by more than 10%, and this increase lasts for more than 5 seconds but less than 60 seconds, so as to reduce the amount of gas in the pump. The controller 40 then controls the motor 10 to return to its rated speed or standby speed, which is less than the rated speed. The exhaust valve 20 closes, and the pump 30 continues to run but with little or no airflow. Because the amount of gas in the pump has been reduced before entering the standby state, the power required for this operation is reduced, and therefore, the power consumed in standby mode is also reduced accordingly.

[0069] In some embodiments, the controller 40 may be configured to periodically increase the speed of the motor 10 in response to detecting an increase in the amount of gas in the pump 30. This may be due to leakage into the system, and the repeated increases ensure that the power required for standby operation remains at or near a low level. The controller 40 may determine this situation in response to receiving a signal from a sensor, such as a power consumption sensor 42, which determines that the power consumption used to drive the pump in standby mode has increased above a predetermined amount. In some cases, the controller may also determine the frequency at which this speed increase is needed, i.e., the time elapsed between each increase cycle, and when said frequency exceeds a predetermined threshold, the controller 40 may output a warning indication.

[0070] Figure 2A The diagram schematically illustrates how the pressure inside the pump changes when there is no gas throughput and the check valve is closed at rated rotational speed and lower standby rotational speed. The pressure varies from inlet to outlet, with a lower pressure at the inlet connected to the vacuum system being evacuated and a higher pressure at the outlet. The pressure at the outlet is the pressure required to open the check valve, because if the pressure is higher than this, the valve will open.

[0071] By reducing the rotational speed, power consumption is reduced in standby mode, resulting in a different pressure distribution within the pump, with higher pressure at the inlet and lower pressure at the outlet. The area under the curve remains constant because the amount of gas in the pump remains constant.

[0072] Figure 2B The effect of increasing the pump's speed is illustrated. As shown, this speed increase alters the pressure distribution within the pump, causing the inlet pressure to decrease and the outlet pressure to increase. The outlet pressure rises above the pressure required to open the check valve, and the valve opens, allowing gas to escape from the pump. The check valve remains open until the outlet pressure drops below its opening pressure, at which point it closes. The amount of gas expelled is schematically shown by the shaded area. When the pump returns to its rated speed, there is less gas in the pump, and both the inlet and outlet pressures are lower, and the power consumption required to maintain this pressure distribution is similarly reduced. The lower standby rotational speed results in an increase in inlet pressure and a decrease in outlet pressure, along with additional power savings.

[0073] As can be seen from the above, overspeeding works by removing gas from the mechanism and reducing the amount of gas in the pump. Once this is done, less power is required to maintain a specific rotational speed, and if the pump rotation is slowed down to further reduce power, the impact on the inlet pressure is smaller.

[0074] Figure 3 A flowchart schematically illustrates the steps in the method according to an embodiment. In step S10, the pumping mechanism is driven at a rated speed. In step S20, a signal indicating that the pump will enter a standby mode is received. This signal can be received from a sensor or from a user, the sensor being associated with the pump or with a vacuum system being evacuated. It can also be received from a secondary pump located between the vacuum system and this pump. In response to this signal, in step S30, the speed of the mechanism is increased for a predetermined time to reduce the amount of gas in the pumping mechanism. In step S40, the speed of the pumping mechanism is reduced, and the pump operates in standby mode with the exhaust check valve closed.

[0075] In step D5, it is determined whether the gas volume in the pump has risen above a predetermined amount. This can be determined by a sensor (such as a sensor that senses that the power consumption of this pump or secondary pump has risen above a predetermined amount). If there is no indication that the gas volume has increased excessively, operation continues in standby mode. If it has increased, the method proceeds to step D15, where it is determined whether the time elapsed since the last detection of this gas volume increase is less than a predetermined time. If so, a warning indication indicating that the pump may not be operating properly is output at S50, and the method returns to step S30, where the speed of the pumping mechanism is increased. If the elapsed time is not less than the predetermined time, the method proceeds directly to step S30, where the speed of the pumping mechanism is increased.

[0076] Figure 4 The diagram schematically illustrates how the power consumed by the pump's motor changes over time. Therefore, normal power consumption exists during normal operation. Upon receiving an instruction from the user that the pump will enter standby mode, in this embodiment, the instruction originates from the user, an increase in pump speed is performed, resulting in a temporary increase in power consumption as shown in the diagram. The pump then enters standby mode and power consumption decreases significantly. Here, the gas volume in the pump is low, there is no gas throughput, and the power consumption is therefore significantly reduced. In some cases, there may be some gas leakage, and power consumption may gradually increase as the gas volume increases, as shown by the dashed lines. At some point, a further boost can be performed, whereby the pump speed is increased to again reduce the gas volume in the pumping mechanism, after which the power consumption will return to a low value. The power-saving mode can be canceled by the user instructing normal pumping operation to resume. In other embodiments, where the power-saving mode is automatically triggered by a sensor (possibly a power sensor), the power-saving mode can also be exited if it is determined that the initial rate of increase in power consumption is too high, indicating that the pump has entered power-saving mode at an inappropriate time while some gas throughput still exists.

[0077] In summary, in this embodiment, a temporary increase in rotational speed is used to expel more gas from the pumping mechanism before returning to standard / normal speed or possibly even lower standby speed. If there is no gas throughput, the amount of gas remaining in the mechanism (the total product of pressure and volume) is lower than before, and a check valve at the pump outlet prevents or at least hinders atmospheric gas from leaking back. The gas pressure is lower, therefore less power is required to compress the gas.

[0078] Figure 1 An embodiment with a vortex pump mechanism is shown, but other embodiments with other main vacuum pumps, such as multistage Roots pumps, claw pumps, diaphragm pumps, reciprocating piston pumps, and rotary vane pumps, are also applicable to this technology. Figure 5 A side-channel blower 50 according to an embodiment is shown. The side-channel blower is a regenerative pump type that uses viscosity to entrain fluid flow 57 in a side channel 58 of the pump. In this embodiment, gas can enter the pump at the inlet, and an impeller 54 can rotate about a rotation center 53, with blades 52 confining the gas in blade sections 56 between them. The impeller rotates counterclockwise from the inlet toward the outlet. The blades 52 do not reach the housing wall 53, and a side channel 58 exists. Gas within the side channel is entrained by viscosity to move with the blades from the inlet toward the outlet. A stripper 51 is present near the outlet, which closes or reduces the cross-section of the side channel so that gas within the side channel is pushed out through the outlet into an outlet channel 62. A check valve 20 is present on the outlet channel 62, and the check valve 20 is controlled by a control circuit 40.

[0079] During operation, when the control circuit 40 determines that the pressure at the inlet has reached the required or ultimate pressure (this pressure determination may be based on pressure sensor readings or motor characteristics), the control circuit 40 sends a signal to the motor driving the impeller 54 to increase its rotational speed and further reduce the pressure inside the pump. Then, the control circuit 40 closes the check valve 20 and controls the motor to return to its rated speed or standby speed, which is lower than the rated speed. The impeller 54 continues to rotate, but there is little or no airflow through the pump. Because the amount of gas inside the pump has been reduced before entering the standby state, the power required for this operation is reduced.

[0080] While the embodiments are particularly effective for zero-throughput conditions, they are also applicable to low gas flow at the pump inlet or low gas flow due to internal pump leakage. Despite the gas load, the proposed temporary velocity increase will enable power reduction until the gas load eventually changes the pressure distribution back to its original state. If this occurs rapidly due to a large gas flow, it is not worthwhile to perform a boost cycle; however, if the gas flow is small, it may be worthwhile to undergo this cycle periodically. The flow rate at which the method will not be worthwhile will depend on the pump size and capacity.

[0081] If the main pump is part of a vacuum system that also includes secondary pumps (such as turbomolecular pumps), the trigger for the boost / standby cycle can be derived from the turbopump power consumption; and the trigger for the repetitive cycle in the event of a small gas throughput or leakage can also be derived from the turbopump power (which would be a particularly sensitive indicator).

[0082] In the presence of a vacuum system with a secondary pump, in some cases, the valve at the secondary pump inlet may also be closed at or approximately simultaneously with the vent valve, so that the boost cycle will also reduce the pressure within the secondary pump and provide further power savings. In this case, the power consumption of the secondary pump will not provide an indication of the pressure rise within the vacuum chamber, and a separate sensor will be needed to determine when the pump may need to pump the chamber again to maintain the required low pressure.

[0083] The control algorithm used to control the pump may include a PID (proportional-integral-derivative) control loop that adjusts the system response according to the size of the system being evacuated, providing a slower, smoother response for larger systems.

[0084] As described above, once in a low-power standby operating mode, a repeated boost / standby cycle can be invoked in response to a slow rise in system pressure (and pump power); by recognizing this event, the pump is able to flag an error code for the user to warn them of the possibility of a vacuum leak.

[0085] The embodiment may provide a power-saving mode that uses a temporary boost cycle to remove some gas from the system, followed by a reduction in rotational speed to reduce unnecessary operation.

[0086] The mode can be triggered by manual intervention acting on the pump controller or by a signal sent to the pump controller for manual scheduling. The mode can also be triggered automatically, alternatively and / or additionally, by a system-level control signal that also stops the gas throughput, or by a smart sensor that is monitoring pump conditions (such as inlet pressure), or by a sensor that measures the pump's power consumption.

[0087] If necessary, the aforementioned boosting cycle can be repeated, for example, to counteract backflow through the check valve. This can be a time-based response, whether or not required, or a sensor-based response, as a reaction to rising pressure or rising power / current.

[0088] The computer program described above can be stored on a program storage device, such as a digital data storage medium that is machine- or computer-readable and encodes a machine-executable or computer-executable instruction program, wherein the instructions cause a processor to cause a controller to perform some or all of the steps of the methods described above. The program storage device can be, for example, a digital memory, a magnetic storage medium (such as disks and magnetic tapes), a hard disk drive, or an optically readable digital data storage medium. The term non-transitory, as used herein, is a limitation on the medium itself (i.e., tangible, not signal-based), as opposed to a limitation on data storage persistence (e.g., RAM and ROM).

[0089] Although illustrative embodiments of the invention have been disclosed in detail herein with reference to the accompanying drawings, it should be understood that the invention is not limited to the precise embodiments, and that various changes and modifications can be made therein by those skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

[0090] List of reference numerals 10 motors 20 Check valve 30 Vortex Pump 40 Controller 42 sensors 50 side channel blowers 51 Peeler 52 blades 54 Impeller 56. Fluid in the blade section 57 Side Passage 58 Streams 59. Housing 60 Airflow at the entrance 62 Exit Channel

Claims

1. A method of controlling a mechanical vacuum pump to reduce power consumption of the pump during a standby mode, the method comprising: operating the pump by driving a pumping mechanism at a rated speed; determining that the pump is to enter a standby mode in which an exhaust check valve is closed; boosting the speed of the pumping mechanism for a predetermined time to reduce an amount of gas within the pump; and reducing the speed of the pumping mechanism and operating the pump in the standby mode with the exhaust check valve closed. The step of boosting the speed of the pumping mechanism comprises increasing a rotational speed of a motor driving the pumping mechanism.

2. The method of claim 1, wherein, The step of reducing the speed of the pumping mechanism comprises reducing the speed to the rated speed.

3. The method of claim 1 or 2, wherein, The step of reducing the speed of the pumping mechanism comprises reducing the speed to a reduced speed that is lower than the rated speed.

4. The method of claim 1 or 2, wherein, The step of determining that the pump is to enter a standby mode comprises at least one of: receiving a control signal from a user, receiving a control signal from a vacuum system associated with the pump, and receiving a control signal from at least one sensor.

5. The method according to any one of the preceding claims, wherein, The step of determining that the pump is to enter a standby mode comprises receiving a control signal from at least one sensor that senses motor power consumption, the sensor indicating that the power consumption is at or near a value indicative of low or zero gas throughput; the method comprising a further step, after the step of reducing the speed of the pumping mechanism, of determining an increasing rate of power consumption, and exiting the standby mode when the increasing rate of power consumption is greater than a predetermined level.

6. The method of claim 5, wherein, The method comprises a further step performed during the standby mode:

7. The method of any of the preceding claims, wherein, determining that the amount of gas within the pump is to be reduced; boosting a rotational speed of the pump for a predetermined time to reduce an amount of gas within the pump; and reducing the rotational speed and returning to operating in the standby mode. The determining step comprises at least one of: determining that power consumption of the pump or a secondary pump in the same system has increased by or to a predetermined amount; determining that pressure has increased by or to a predetermined amount; determining that a predetermined time has elapsed since a previous speed boost; or determining that a signal has been received from an operator or from a vacuum system.

8. The method of claim 7, wherein, 9. The method of any of claims 6 to 8, further comprising determining a frequency at which the boosting is repeated during the standby mode, and outputting a warning indication to an operator in response to determining that the frequency has increased by more than a predetermined threshold amount. The mechanical vacuum pump comprises one of a positive displacement pump or a regenerative pump.

10. The method of any of the preceding claims, wherein, 11. A computer program comprising computer readable instructions configured to control a mechanical vacuum pump to perform a method according to any of the preceding claims when executed by a processor of a controller of the pump.

12. A controller for a mechanical vacuum pump, the controller comprising: control circuitry configured to control a speed of a pumping mechanism of the pump, the control circuitry configured to: control the pump such that the pumping mechanism is driven at a rated speed; and ​ ​ in response to receiving a signal indicating that the pump is to enter a standby mode, in which the exhaust check valve is closed to control the pump to increase a speed of the pumping mechanism for a predetermined time to reduce an amount of gas within the pump; and after the predetermined time, reducing the speed of the pumping mechanism and continuing to drive the pumping mechanism in the standby mode with the exhaust check valve closed.

13. The controller of claim 12, wherein, the step of reducing the speed of the pumping mechanism includes reducing the speed to the rated speed.

14. The controller of claim 12, wherein, the step of reducing the speed of the pumping mechanism includes reducing the speed of the pumping mechanism to a low power speed that is lower than the rated speed.

15. The controller of any one of claims 12 to 14, wherein, the signal is received from at least one of: a user, a control system, or a sensor.

16. The controller of any one of claims 12 to 15, wherein, the control circuit is further configured to, in response to receiving a signal during a standby mode, the signal indicating that an amount of gas within the pump is to be reduced; controlling the motor to increase a rotational speed of the pump for a predetermined time to reduce an amount of gas within the pump; and after the predetermined time, reducing the speed of the pumping mechanism and returning to controlling the pump to operate in the standby mode.

17. The controller of any one of claims 12 to 16, wherein, the signal is generated in response to at least one of: an increase in power consumption of the pump by a predetermined amount or to a predetermined amount, an increase in pressure at the pump inlet by a predetermined amount or to a predetermined amount, a predetermined time has elapsed since a previous increase in speed, or an input from an operator or from a control system.

18. A mechanical vacuum pump comprising: a motor for driving the pump; a check exhaust valve; and a controller according to any of claims 12 to 17 for controlling operation of the mechanical vacuum pump.

19. The mechanical vacuum pump of claim 18, wherein, the vacuum pump comprises one of a positive displacement pump or a regenerative pump.

20. The mechanical vacuum pump of claim 18 or 19, wherein, the vacuum pump comprises a scroll pump.

21. A vacuum system comprising a primary vacuum pump according to any of claims 18 to 20 and a secondary vacuum pump comprising a valve at an inlet, the controller being configured to close the inlet valve in response to receiving a signal that the pump is to enter a standby mode.

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