Reducing power consumption in vacuum pumps

Abstract

A vacuum pump and a method for controlling such a pump to reduce the power consumption of the pump during standby mode. The method includes operating the pump by driving the pumping mechanism at a nominal speed, deciding to put the pump into standby mode with the exhaust check valve closed, boosting the speed of the pumping mechanism for a predetermined time to reduce the amount of gas in the pump, and reducing the speed of the pumping mechanism to operate the pump in standby mode with the exhaust check valve closed.

Description

Technical Field

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

Background Art

[0002] In mechanical vacuum pumps such as positive displacement vacuum pumps, the total power consumption is a combination of useful power (used to move and / or compress the gas) and losses. The losses are mainly those related to electrical and magnetic efficiency (motor and drive), and parasitic losses (gas leakage, cooling fans, friction). Although it is clear that losses can be reduced by improved design, it is more difficult to reduce the power introduced in the gas movement / compression.

[0003] In many applications, whether evacuating a chamber or pumping a steady gas flow at low pressure, the vacuum pump spends at least part of its operating time maintaining the vacuum and operating with little or no gas throughput. During this mode, the exhaust check valve is generally closed. "Green" modes or "standby" modes already exist, and these usually involve reducing the rotational speed to reduce frictional losses (Power = Torque × Angular Velocity, and torque includes bearing frictional losses). The reduction in speed results in different pressure distributions and higher ultimate pressures, and the reduction in power consumption can be quite modest compared to the best savings, especially when turning the pump completely off.

[0004] In particular, it is desirable to be able to reduce the power consumption of the vacuum pump when it is operating in a standby mode with little or no gas throughput and often pumping at or near the ultimate pressure of the pump.

Summary of the Invention

[0005] A first aspect provides a control method for a mechanical vacuum pump to reduce the power consumption of the pump during standby mode, the method comprising: operating the pump by driving a pumping mechanism at a nominal speed; determining that the pump enters standby mode in which an exhaust check valve is closed; boosting the speed of the pumping mechanism at a predetermined time in order to reduce the amount of gas in the pump; and operating the pump in standby mode in which the exhaust check valve is closed by reducing the speed of the pumping mechanism.

[0006] Many mechanical pumps, such as positive displacement pumps that operate as primary pumps and evacuate to the atmosphere, are equipped with check valves to mitigate the effects of failure modes and prevent the pump from returning to atmospheric pressure on a short timescale. Check valves also improve pump efficiency, and in steady states where there is no gas throughput, the valves are closed. A mode in which the valve is closed for a certain period of time and there is little to no gas throughput can be called a standby mode, during which the pump simply maintains the vacuum in the space being pumped.

[0007] It was recognized that in standby mode, when the check valve is closed and the pump is simply pumping to maintain the pressure in the chamber, the gas inside the pump can move and / or compress with each cycle and then expand again. This consumes energy. It was also recognized that if the amount of gas in the pump is reduced during standby mode, the amount of energy required to provide the periodic movement and / or compression of gas within the pump is reduced. Therefore, the present invention provides a speed boost to the pump before entering or during this standby mode so that the amount of gas in the pump is reduced and the energy required for the periodic movement and / or compression of gas within the pump in this mode is correspondingly reduced. There is some increase in power required for the speed boost, and the increase in speed increases wear on pump components such as bearings, but since the increase in speed is only required for a short period of time, power can be saved overall.

[0008] In this way, the embodiment provides a means for achieving significant power savings without compromising pump inlet pressure when operating with little to no gas throughput.

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

[0010] Boosting the pumping mechanism speed increases the pump's volumetric capacity, which in some cases increases the pump's compression and decreases the amount of gas inside the pump.

[0011] In some embodiments, the predetermined time described above exceeds 1 second, preferably 3 seconds, and in some cases exceeds 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 nominal rotational speed, preferably more than 10%.

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

[0015] In other embodiments, the step of reducing the speed of the pumping mechanism includes reducing the speed to a reduction speed lower than the nominal speed.

[0016] In some embodiments, the rate of decrease is more than 10% lower than the nominal rate.

[0017] In standby mode, with the exhaust check valve closed, the pump can be allowed to operate at a speed lower than its nominal speed, thereby reducing power consumption.

[0018] In some embodiments, the step of determining whether the pump enters standby mode includes 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.

[0019] The pump may decide to enter standby mode in response to a signal received from the user, or a control signal from the vacuum system the pump is exhausting, and / or a control signal from a sensor associated with the pump or the vacuum system.

[0020] The sensor can be a power sensor that senses the power of the motor of this pump, or, if this pump is assisting a secondary pump, the power of the secondary pump.

[0021] Alternatively and / or in addition thereto, the signal may come from a pressure sensor that senses the pressure inside the chamber, or a pressure sensor that senses the pressure inside the pump or the pressure elsewhere in the associated vacuum system, and / or a sensor that indicates that the exhaust check valve is closed and remains closed for a predetermined time. The signal from the vacuum system may come from a control system that controls the vacuum system and / or the pump.

[0022] In some embodiments, the step of determining that the pump enters 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 or zero gas throughput, and the method further includes the step of reducing the speed of the pumping mechanism, followed by the step of determining a rate of increase in power consumption, and if the rate of increase in power consumption is greater than a predetermined rate of increase, the standby mode is terminated.

[0023] If the pump enters standby mode by detecting a power consumption value indicating no gas throughput or being close to it, an additional step can be performed after entering low-power mode to verify that the pump actually reached zero gas throughput. This additional step monitors the rate of increase in power consumption, and if this rate of increase is higher than expected and exceeds a threshold, it accurately indicates that the pump did not reach zero gas throughput. In this case, the pump may exit low-power mode and resume normal operation. In practice, mechanical losses dominate the pump's power consumption at low gas throughput, making it difficult to accurately detect zero gas throughput. However, once in low-power mode, the power sensor can accurately detect the presence of gas throughput because the increase in power consumption is relatively steep. Therefore, by incorporating this additional check, low-power mode can be exited when appropriate. Since the power boost is relatively short-lived and subsequently leads to power savings anyway, this trial-and-error approach has few drawbacks and can provide effective power savings.

[0024] In some embodiments, the method includes further steps performed during the standby mode, which include deciding to reduce the amount of gas in the pump, boosting the rotational speed of the pump for a predetermined time to reduce the amount of gas in the pump, and reducing the rotational speed to return to operation in the standby mode.

[0025] During standby mode, the amount of gas in the pump may gradually increase due to gas leakage into the pump. In some cases, this method may include a step of determining this and, in response, a step of boosting the speed again to reduce the amount of gas in the pump. In this way, even if there is a small gas flow due to leakage into the system, the amount of gas in the pump can be kept at a low level for a long period of time.

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

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

[0028] In some embodiments, the determining step includes determining that the pressure in the pump or in the pumped chamber or 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 an operator in response to determining that the frequency has increased above a predetermined threshold amount.

[0030] The frequency at which the speed needs to be boosted during the standby mode is an indicator of the degree of leakage into the pump or vacuum system and can thus be an indicator of a fault in the system. Thus, in some cases, monitoring this frequency and confirming that it exceeds a predetermined level can be used to indicate a fault in the system.

[0031] A further aspect provides a computer program including computer-readable instructions configured to control the pump to execute a method according to one aspect when executed by a processor in a controller of a mechanical vacuum pump.

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

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

[0034] In some embodiments, the control loop is configured to determine the predetermined time for boosting the pump speed, depending 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 possibly greater than 5 seconds. In some embodiments, the predetermined time is less than 120 seconds, preferably less than 60 seconds.

[0035] Pumps can be used to exhaust different systems, which may vary in size. The length of time the pump speed should be boosted depends on the system being exhausted, with larger systems likely requiring longer periods. In some embodiments, a computer program within the pump's controller may have a PID control loop that can be operated to adjust the pump to reflect the size of the system being exhausted, thereby providing an appropriate boost period.

[0036] Another embodiment 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 so that the pumping mechanism is driven at a nominal speed, and in response to receiving a signal indicating that the pump is entering a standby mode in which an exhaust check valve is closed, to control the pump so that the speed of the pumping mechanism is increased for a predetermined time to reduce the amount of gas in the pump, and after the predetermined time has elapsed, to control the pump so that the speed of the pumping mechanism is reduced to continue driving 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 nominal 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 lower than the nominal speed.

[0039] In some embodiments, the signal is received from at least one of 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 whether a valve is closed and remains closed for a predetermined time.

[0041] In some embodiments, if the sensor is a power sensor, the sensor is further configured to determine the rate of increase in power consumption after the pumping mechanism has reduced its 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 control the motor in response to receiving a signal during standby mode indicating a reduction in the amount of gas in the pump, thereby boosting the rotational speed of the pump for a predetermined time to reduce the amount of gas in the pump, and after the predetermined time, to control the pump so that it operates in standby mode by reducing the speed of the pumping mechanism.

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

[0044] Another embodiment provides a mechanical vacuum pump comprising a motor for driving the pump, a check valve for exhaust, and a controller according to another embodiment for controlling the operation of the mechanical vacuum pump.

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

[0046] In some embodiments, the mechanical vacuum pump includes one of a positive displacement pump or a regenerative 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 the following: scroll, multistage roots, screw, claw, diaphragm, reciprocating piston, or rotary vane pump.

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

[0050] A vacuum pump according to one embodiment, which has a check valve close to the pump, provides a particularly effective power reduction because the effect of reducing the amount of gas in the pump by speed boosting the pump mechanism increases as the gas volume between the valve and the pump decreases. A ported pump, such as a ported screw pump, has a valve on the port at the exhaust of the pump, and therefore the volume between the valve and the pump is extremely small.

[0051] It should be noted that some vacuum pumps may contain impurities such as liquids and particles in the exhaust flow, which can clog the exhaust valve. One way to mitigate this is to provide a plenum through which the pump exhausts, which protects the valve from impurities, but this increases the volume between the pump and the valve, thus reducing the power reduction effect of speed boosting. Dry pumps do not require such valve protection and therefore the valve can be placed closer to the pump. Scroll pumps are generally configured with a check 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 within the pump. Therefore, similar to positive displacement pumps, the power consumption of the pump can be reduced by decreasing the amount of gas in the pump when it is operating with the exhaust valve closed at virtually zero throughput.

[0054] A further embodiment provides a vacuum system including a vacuum pump according to another embodiment, wherein the vacuum pump includes a primary vacuum pump, and the vacuum system further includes a secondary vacuum pump, wherein the secondary vacuum pump is equipped with an inlet valve, and the controller is configured to close the inlet valve in response to receiving a signal indicating that the pump is entering standby mode.

[0055] In vacuum systems involving multiple pumps, power consumption can be further reduced by decreasing the amount of gas in both the secondary and primary vacuum pumps during virtually zero-throughput operation. This may be done by closing the inlet of the secondary vacuum pump when the target pressure is reached, either immediately before, during, or immediately after the primary pump speed boost. "Immediately after" can mean within 5 seconds, preferably 1 second, of the end of the speed boost. In such situations, a sensor that senses the pumping vacuum chamber may be required to indicate to the controller when the pressure in the vacuum chamber has risen so that the valve can be opened and the pump system can operate again.

[0056] Further specific and preferred embodiments are described in the attached independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and may also be combined in combinations other than those expressly described in the claims.

[0057] When a feature of a device is described as being capable of operating to provide a function, it is understood that the feature of that device includes things that provide that function, or things that are adapted or configured to provide that function.

[0058] Embodiments of the present invention will be further described below with reference to the accompanying drawings. [Brief explanation of the drawing]

[0059] [Figure 1] A scroll pump and controller according to one embodiment are shown. [Figure 2A]The pressure distribution inside the pump in the absence of gas throughput is schematically shown with and without velocity boost. [Figure 2B] The pressure distribution inside the pump in the absence of gas throughput is schematically shown with and without velocity boost. [Figure 3] A flow diagram illustrating the steps in one embodiment of the method is shown. [Figure 4] This figure shows how the power consumption of a vacuum pump according to one embodiment can change over time. [Figure 5] This figure shows a side channel blower according to one embodiment. [Modes for carrying out the invention]

[0060] Before describing the embodiments in detail, let's first give an overview.

[0061] Positive displacement pumps, such as scroll vacuum pumps, generally have a check valve at the outlet to prevent atmospheric ingress. The valve is closed by a spring with a low spring constant, and its primary function is to prevent downstream gas from flowing back into the user's system when the scroll pump is stopped, and to maintain the vacuum even in the event of a power failure. Installing a shut-off valve at the pump inlet is an alternative technical solution, but it is more expensive and imposes limitations on gas conductance.

[0062] During steady-state operation with little to no gas throughput, this check valve is closed. The pump contains a finite amount of captured gas, and under these conditions, gas compression power is consumed to maintain a pressure gradient between the inlet and outlet. The majority of the gas is in the final stage, where the pressure is close to atmospheric pressure.

[0063] If the captured gas in the final stage can be discharged or isolated, the steady-state power requirements will be reduced.

[0064] The embodiment provides a solution in which, when gas throughput is substantially zero, the pump is operated for a short period at a rotational speed higher than the normal rated speed (to improve performance and discharge additional gas), and then returned to the normal speed or a lower standby speed to take advantage of the reduced gas load.

[0065] A steady state is achieved when the pump operates without gas throughput. The gas within the pumping mechanism is distributed according to the pump's compression characteristics. The outlet check valve no longer opens because the pressure in the final stage is insufficient to overcome the valve spring.

[0066] Increasing the pump's rotational speed improves its ability to resist back leaks, and the pressure distribution shifts further towards the outlet. The pressure in the final stage increases enough to open the check valve, pushing more gas out of the pump. After a short time, the pump can return to its nominal speed, but the power required is reduced because the pressure in the final stage has decreased. (While the overall performance of the pump may improve with continuous operation at high speeds, this is not desirable in the long term due to the increased load on the bearings).

[0067] If the pressure in the final stage is reduced, the rate of internal leakage through the other stages is also reduced, so even if the pump speed is lower than nominal, it is possible to maintain a low ultimate pressure, resulting in further power savings. Such pumps usually already have an optional "standby" deceleration rate, but this causes an increase in inlet pressure. The embodiment aims to reduce power without degrading vacuum performance, and if the degradation of performance is actually acceptable, the preferred way to save power would be to slow down the pump or stop it completely.

[0068] In some embodiments, existing pumps can be retrofitted with appropriate control circuits that allow the pump to cycle through a sequence when gas throughput is reduced to zero or near zero. This enables short periods of high-speed operation (e.g., only 30 seconds). This process may be manually controlled or automated. If automated, the pump should recognize conditions of no gas flow. Doing this using a power sensor can be difficult because the power consumption at zero gas throughput is similar to that at low gas throughput, as mechanical losses are dominant. In some embodiments, this is addressed by initiating a speed boost cycle and a low-power standby mode when power consumption drops to a certain value, and possibly additionally, when the standby mode has not been triggered for a predetermined time. The rate of increase in power consumption is then checked, and if it is greater than expected, it indicates that gas throughput exists and therefore it is inappropriate to apply power saving. In this case, the pump is controlled to exit power saving mode. The threshold for the rate of increase indicating gas throughput depends on the type and size of the pump and, possibly, the system being pumped, and is set for a particular pump and setup.

[0069] Figure 1 shows a scroll pump 30 according to an embodiment. The scroll pump 30 includes a check valve 20, which may be a spring-loaded valve configured to open under a pressure difference and close when the pressure at the pump outlet is below atmospheric pressure. In this way, the pump can be sealed when it is no longer pumping gas, i.e., when the inlet pressure reaches the ultimate pressure. The scroll pump 30 includes a motor 10 that drives the scroll pump and a controller 40 that controls the operation of the motor. In this embodiment, there is also a sensor 42 associated with the motor 10 that senses the power consumption of the motor. During operation, the controller 40 controls the motor 10 to drive the scroll pump to evacuate the chamber until a steady state is reached, i.e., the ultimate pressure at the inlet is reached, the valve 20 is closed, 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 is entering standby mode. At this point, the controller 40 boosts the operating speed of the motor 10 by more than 10% above the nominal rotational speed for a period of more than 5 seconds but less than 60 seconds to reduce the amount of gas in the pump. Subsequently, the controller 40 controls the motor 10 to return it to a standby speed lower than or equal to the nominal speed, the exhaust valve 20 closes, and the pump 30 continues to operate with little to no gas flow. Because the amount of gas in the pump is reduced before the pump enters standby mode, the power required for this operation is reduced, and therefore the power consumed during standby mode is also reduced accordingly.

[0070] In some embodiments, the controller 40 may be configured to periodically increase the speed of the motor 10 when it detects an increase in the amount of gas in the pump 30. This may be due to a leak into the system, and repeated boosts keep the power required for standby operation at a low level or close to it. The controller 40 may determine this in response to receiving signals from sensors, such as a power consumption sensor 42, which determines that the power consumption required to drive the pump in standby mode has increased beyond a predetermined amount. In some cases, the controller may also determine how often this speed boost is required, i.e., the elapsed time between each boost cycle, and if this frequency exceeds a predetermined threshold, the controller 40 may output a warning signal.

[0071] Figure 2A schematically shows curves illustrating how the pressure inside the pump changes at nominal and lower standby speeds, with no gas throughput and the check valve closed. The pressure changes from the inlet to the outlet, with lower pressure at the inlet connected to the vacuum system being exhausted and higher pressure at the outlet. The outlet pressure is the pressure required to open the check valve; the valve opens when the pressure exceeds this value.

[0072] In standby mode, power consumption is reduced by decreasing the rotation speed, which changes the pressure distribution within the pump, resulting in higher inlet pressure and lower outlet pressure. Since the amount of gas in the pump does not change, the area under the curve remains constant.

[0073] Figure 2B illustrates the effect of pump speed boosting. As shown, speed boosting alters the pressure distribution within the pump, causing a decrease in inlet pressure and an increase in outlet pressure. The outlet pressure rises to a level exceeding the pressure required to open the check valve, causing the valve to open and gas to be discharged from the pump. The check valve remains open until the outlet pressure falls below the valve's opening pressure and it closes. The amount of gas discharged is schematically shown by the shaded area. When the pump returns to its nominal speed, the amount of gas in the pump is reduced, causing both inlet and outlet pressures to decrease, and the power consumption required to maintain this pressure distribution is similarly reduced. Lower standby rotational speeds result in increased inlet pressure and decreased outlet pressure, providing additional power savings.

[0074] As can be seen from the above, overspeeding works by removing gas from the mechanism and reducing the amount of gas in the pump. When this is done, less power is required to maintain a given rotational speed, and even if the pump's rotation is slowed down to further save power, the impact on the inlet pressure is small.

[0075] Figure 3 is a schematic flow diagram showing the steps in the method according to the embodiment. In step S10, the pumping mechanism is driven at nominal speed. In step S20, a signal is received indicating that the pump is entering standby mode. This signal can be received from a sensor associated with the pump or the vacuum system being pumped, or from the user. 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 pumping mechanism is boosted 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.

[0076] In step D5, it is determined whether the amount of gas in the pump has increased beyond a predetermined amount. This may be determined by sensor signals, such as those from a sensor that detects an increase in the power consumption of this pump or secondary pump beyond a predetermined amount. If there is no indication that the amount of gas has increased excessively, operation continues in standby mode. If the amount of gas has increased, the method proceeds to step D15, where it is determined whether the time since this increase in the amount of gas was last detected is shorter than a predetermined time. If it is shorter than the predetermined time, a warning message indicating that the pump may not be operating properly is output in step S50, and then the method returns to step S30 to boost the pumping mechanism speed again. If it is not shorter than the predetermined time, the method proceeds directly to step S30, where the pumping mechanism speed is boosted.

[0077] Figure 4 schematically illustrates how the power consumption of the pump motor changes over time. As can be seen from the figure, there is normal power consumption during normal operation. In this embodiment, after the pump receives an instruction from the user to enter standby mode, the pump speed is boosted, resulting in a temporary increase in power consumption as shown in the graph. Subsequently, the pump enters standby mode, and power consumption drops significantly. Here, the amount of gas in the pump is low and there is no gas throughput, so power consumption is greatly reduced. In some cases, a slight gas leak may increase the amount of gas, causing a gradual increase in power consumption, which is shown by the dashed line. At some point, a further boost is performed to increase the speed of the pump mechanism again, which reduces the amount of gas in the pumping mechanism again, and then power consumption returns to a low value again. The power saving mode can be canceled by the user instructing to resume normal pumping operation. In other embodiments, if the power saving mode is automatically triggered by a sensor, such as a power sensor, the power saving mode can be terminated if it is determined that the initial increase in power consumption is too high, indicating that the pump entered power saving mode at an inappropriate time when gas throughput is still present.

[0078] In summary, the embodiment saves power by temporarily increasing the rotational speed to expel more gas from the pumping mechanism, and then returning to the standard / normal speed or an even lower standby speed. When there is no gas throughput, the amount of gas remaining in the mechanism (total product of pressure × volume) is less than before, and the check valve at the pump outlet prevents or at least prevents atmospheric gas from leaking back in. As the gas pressure decreases, the power required to compress the gas is reduced.

[0079] Figure 1 shows an embodiment having a scroll pump mechanism, but this technology is also applicable to other primary vacuum pumps that can be provided with a check valve at the outlet, such as other embodiments having multistage Roots, claw, diaphragm, reciprocating piston and rotary vane pumps.

[0080] Figure 5 shows a side channel blower 50 according to an embodiment. A side channel blower is a type of regenerative pump that takes in a fluid flow 57 in a side channel 58 of a pump by viscosity. In this embodiment, gas flows into the pump from the inlet, an impeller 54 rotates around a rotation center 53, and blades 52 confine the gas within blade segments 56. The impeller rotates counterclockwise from the inlet to the outlet. The blades 52 do not reach the housing wall 59, where the side channel 58 is present. The gas in the side channel moves with the blades from the inlet to the outlet by viscosity. Adjacent to the outlet is a stripper 51 that closes or reduces the cross section of the side channel, and the gas in the side channel is pushed through the outlet into the outlet channel 62. The outlet channel 62 has a check valve 20 controlled by a control circuit 40.

[0081] During operation, the control circuit 40, for example from pressure sensor readings or motor characteristics, determines that the inlet pressure has reached the desired or target pressure and sends a signal to the motor driving the impeller 42 to boost its rotational speed and further reduce the pressure in the pump. The control circuit 40 then closes the check valve 20 and controls the motor to return to the nominal speed or a standby speed lower than the nominal speed. The impeller 42 continues to rotate, but there is little to no gas flow through the pump. Because the amount of gas in the pump is reduced before the pump enters standby mode, the power required for this operation is reduced.

[0082] The embodiment is particularly effective under conditions of zero gas throughput, but can also be applied to low gas flow rates into the pump inlet or small gas flows due to internal pump leaks. The proposed transient rate increase enables power reduction even in the presence of gas load, and the power reduction is maintained for the period until the pressure distribution returns to its original state due to the gas load. At high gas flow rates, the pressure distribution returns to its original state quickly, making it not worthwhile to perform a rate boost cycle, but at low gas flow rates, it may be worthwhile to perform the cycle periodically. The gas flow rate at which this method becomes ineffective depends on the size and capacity of the pump.

[0083] If the primary pump is part of a vacuum system that includes a secondary pump such as a turbomolecular pump, the boost / standby cycle trigger may be derived from the turbopump's power consumption, and the recycle trigger in the case of low gas throughput or leakage may also be derived from the turbopump's power consumption (this is a particularly sensitive indicator).

[0084] If a vacuum system has a secondary pump, in some cases the valve at the inlet of the secondary pump can also be closed simultaneously with or before / after the check valve, and the boost cycle reduces the pressure in the secondary pump, resulting in further power savings. In this case, the power consumption of the secondary pump no longer indicates a pressure increase in the vacuum chamber, so another sensor is needed to determine when the pump may need to pump the chamber again to maintain the desired low pressure.

[0085] The control algorithm for controlling the pump may include a PID (proportional-integral-derivative) control loop that adjusts the system response according to the size of the system being exhausted, with a slower and smoother response for larger volume systems.

[0086] As mentioned earlier, after entering low-power standby mode, the boost / standby cycle can be executed again in response to a gradual increase in system pressure (and pump power). Recognizing this event, the pump can flag an error code to warn the user of a potential vacuum leak.

[0087] The embodiment provides a power-saving mode that uses a temporary boost cycle to remove a predetermined amount of gas from the system, and then reduces the rotational speed to reduce unnecessary work.

[0088] The mode can be triggered by manual intervention or a manual scheduling signal to the pump controller. Alternatively and / or in addition, the mode can be automatically triggered by a system-level control signal that also stops gas throughput, a smart sensor that monitors pump conditions (e.g., inlet pressure), or a sensor that measures the pump's power consumption.

[0089] The boost cycle can be run again as needed, for example, to address back leaks through a check valve. This may be a time-based response, whether necessary or not, or a sensor-based response, in response to a pressure increase or a power / current increase.

[0090] The computer programs described above can be stored on program storage devices, such as digital data storage media, which are machine or computer readable and encode machine-executable or computer-executable programs of instructions, which the processor uses to cause a controller to execute some or all of the steps of the method described above. The program storage devices can be, for example, digital memory, magnetic storage media such as magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. As used herein, the term “non-transitory” refers to the limitations of the medium itself (i.e., a tangible medium rather than a signal) and not to limitations on the persistence of data storage (e.g., RAM vs. ROM).

[0091] Exemplary embodiments of the present invention have been disclosed in detail herein with reference to the accompanying drawings, but the present invention is not limited to these exact embodiments, and it will be understood that various changes and modifications can be made without departing from the scope of the invention as defined by the appended claims and equivalents. [Explanation of Symbols]

[0092] 10 motors 20 Check valve 30 Scroll Pump 40 controllers 42 sensors 50 Side Channel Blower 51 Strippers 52 Blades 54 Impeller 56 Fluid within blade segments 57 Side Channel 58 Flow 59 Housing 60 Gas flow at the inlet 62 Exit Channels

Claims

1. A method for controlling a mechanical vacuum pump to reduce its power consumption during standby mode, The pump is operated by driving the pumping mechanism at a nominal speed, It is determined that the pump enters a standby mode in which the exhaust check valve is closed, In order to reduce the amount of gas in the pump, the speed of the pumping mechanism is boosted at a predetermined time, The speed of the pumping mechanism is reduced so that the pump operates in the standby mode with the exhaust check valve closed, Methods that include...

2. The method according to claim 1, wherein the step of boosting the speed of the pumping mechanism includes increasing the rotational speed of the motor that drives the pumping mechanism.

3. The method according to claim 1 or 2, wherein the step of reducing the speed of the pumping mechanism includes reducing the speed to the nominal speed.

4. The method according to claim 1 or 2, wherein the step of reducing the speed of the pumping mechanism includes reducing the speed to a reduction speed lower than the nominal speed.

5. The method according to any one of claims 1 to 4, wherein the step of determining that the pump enters standby mode includes 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.

6. The method according to claim 5, wherein the step of determining that the pump enters standby mode includes receiving a control signal from at least one sensor that senses the power consumption of a motor, the sensor indicating that the power consumption is at or near a value indicating low or zero gas throughput, and the method further includes the step of determining a rate of increase in power consumption, following the step of reducing the speed of the pumping mechanism, and terminating the standby mode if the rate of increase in power consumption is greater than a predetermined level.

7. The aforementioned method, The decision to reduce the amount of gas in the pump, In order to reduce the amount of gas in the pump, the rotational speed of the pump is boosted for a predetermined time, The rotation speed is reduced to return to the standby mode operation, The method according to any one of claims 1 to 6, further comprising additional steps performed during the standby mode, including the following:

8. The aforementioned decision-making step is: The power consumption of the aforementioned pump or the secondary pump of the same system has increased by a predetermined amount or up to a predetermined amount. or the pressure has increased by a predetermined amount or up to a predetermined amount. Or, a predetermined amount of time has elapsed since the speed was last boosted. Or a signal was received from the operator or the vacuum system. The method according to claim 7, comprising determining at least one of the following.

9. The method according to any one of claims 6 to 8, further comprising determining the frequency at which the boost is repeated during the standby mode, and outputting a warning instruction to the operator in response to determining that the frequency has increased above a predetermined threshold amount.

10. The method according to any one of claims 1 to 9, wherein the mechanical vacuum pump includes one of a positive displacement pump or a regenerative pump.

11. A computer program including computer-readable instructions, wherein when the instructions are executed by a processor in the controller of a mechanical vacuum pump, the computer program is configured to control the pump to perform the method according to any one of claims 1 to 10.

12. A controller for a mechanical vacuum pump, The pump is equipped with a control circuit configured to control the speed of the pumping mechanism of the pump, The aforementioned control circuit is The pump is controlled so that the pumping mechanism is driven at a nominal speed. In response to receiving a signal indicating that the pump enters a standby mode in which the exhaust check valve is closed, the pump is controlled to increase the speed of the pumping mechanism over a predetermined period of time to reduce the amount of gas in the pump. And, after the predetermined time has elapsed, the pump is controlled to reduce the speed of the pumping mechanism and to continue driving the pumping mechanism in the standby mode with the exhaust check valve closed. A controller configured in such a way.

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

14. The controller according to 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 lower than the nominal speed.

15. The controller according to 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 control circuit further responds to receiving a signal indicating a reduction in the amount of gas in the pump during standby mode, The motor is controlled to boost the rotational speed of the pump for a predetermined time to reduce the amount of gas in the pump, and After the predetermined time, the pump is controlled to reduce the speed of the pumping mechanism and operate in the standby mode. A controller according to any one of claims 12 to 15, configured as described above.

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

18. A mechanical vacuum pump, A motor that drives the aforementioned pump, A check valve and, A controller according to any one of claims 12 to 17 for controlling the operation of the mechanical vacuum pump, A mechanical vacuum pump equipped with [a specific feature / feature].

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

20. The mechanical vacuum pump according to claim 18 or 19, wherein the vacuum pump includes a scroll pump.

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

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