WO2018199985A1

WO2018199985A1 - Power operation for cooling mechanisms

Info

Publication number: WO2018199985A1
Application number: PCT/US2017/030147
Authority: WO
Inventors: Duane A. Koehler; Robert Davis; Michael Ewe
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2017-04-28
Filing date: 2017-04-28
Publication date: 2018-11-01

Abstract

A printer includes a controller to manage power usage for active cooling mechanisms in the printer cooling system based on a total amount of power available to the cooling system and temperatures measured by a number of temperature sensors.

Description

POWER OPERATION FOR COOLING MECHANISMS

BACKGROUND

[0001] Operating mechanical and electronic devices produces heat that may have to be removed from the devices in order to maintain temperatures within desirable limits. Failure to remove heat effectively may result in increased device temperatures, potentially leading to thermal runaway conditions that can interfere with device operation and damage components within the device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The disclosure herein is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements, and in which :

[0003] FIG. 1 illustrates an example apparatus with a cooling system using cooling margin power management;

[0004] FIG. 2 illustrates an example printer with a housing divided into cooling zones;

[0005] FIG. 3 illustrates an example printer with a power monitor and controller to determine a total amount of power available to a cooling system;

[0006] FIG. 4 illustrates an example method for cooling in an apparatus;

[0007] FIG. 5A illustrates an example method for cooling margin power management;

[0008] FIG. 5B illustrates an example method for determining zone cooling priority;

[0009] FIG. 6 illustrates an example method for allocating power to a cooling system using a power monitor; and

[0010] FIG. 7 illustrates an example method for reallocating power in an apparatus.

[0011] The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the examples shown . The drawings provide examples and implementations consistent with the description. However, the description is not limited to the examples and implementations provided in the drawings.

DETAILED DESCRIPTION

[0012] An apparatus is provided herein that includes a controller to allocate a fixed or measured amount of power between cooling mechanisms (e.g., fans) in the apparatus. A power monitor can periodically measure source voltage and current to determine the amount of power available for the controller to allocate between the fans in the cooling system. In the event that not enough power is available to run every fan at full power (e.g., during a power sag or heavy device usage), the controller prioritizes available power between the cooling fans as necessary to prevent overheating of apparatus components. The prioritization is performed based on predictive methods and monitored temperatures of each cooling zone (or component) within the apparatus, with priority placed on fans in zones that may exceed their maximum allowed temperatures soonest.

[0013] Examples provide for a printer or printing device including a controller to manage power usage for a cooling system in the printer based on a total amount of power available to the cooling system and temperatures measured by a number of temperature sensors. In some examples, the cooling system includes a number of active cooling mechanisms, such as fans, to remove waste heat generated by components of the printer or to introduce cooler air to the printer housing. In some examples, the housing is divided into a number of cooling zones, or thermal zones, which are at least partially thermally or spatially isolated from each other. A sensor is located in each zone to report the zone temperature to the controller, and the controller calculates cooling margins for each zone based on the temperatures, a threshold temperature for each zone, and a thermal rate of change for that zone. The controller determines whether to enable, disable, or throttle the fans disposed to transfer heat from each zone based on a comparison of the cooling margins calculated for each of the zones.

[0014] Examples recognize that voltage sags can occur because of line- to-ground faults caused by lightning, falling objects, accidents, etc., or also because of sudden load changes and excessive loads within a device. When sags occur, the reduced voltage can cause device components to fail, resulting in production errors or even damage to the device.

[0015] Devices such as 3D printers contain many fans used to cool various regions, or zones, within the printer. All together, these cooling fans can consume hundreds of watts of power when operating at maximum output. In addition, heating elements and blowers in a 3D printer consume even more significant amounts of power. Therefore, it is possible to overload the system when the fans are fully on . If each fan operated on its own independent servo, the fans could simultaneously come on and trip the circuit breaker or cause the voltage to sag and print bad parts.

[0016] In devices where running the fans at the same time would overload the circuit during low-line or sag events, one solution is to power the product from a more capable circuit. For example, in Europe, this could mean moving from a single 16A service to two power cords. For larger devices, this could force a move from single-phase to three-phase power. Alternatively, product performance could be limited to constrain the worst- case power load to what the smaller circuit can support during a sag.

[0017] Among other benefits, the examples described herein achieve a technical effect of enabling a device to meet its performance requirements without forcing a user to install a more capable alternating current (AC) service for the device. In addition, examples can increase the maximum performance for a device on a given AC service. Examples can further enable the use of a smaller power supply unit (12V, 24V, etc.) to power cooling fans in the device to reduce costs.

[0018] By using available cooling margins to disconnect high-power fan loads, examples can prevent a catastrophic device shutdown due to short- term voltage sag in a way that is transparent to the customer with no perceptible impact on device function. In addition, examples can take advantage of existing system fan controls and temperature sensors.

[0019] APPARATUS DESCRIPTION

[0020] FIG. 1 illustrates an example apparatus with a cooling system using cooling margin power management. An apparatus 100 can include a controller 110, a power supply 120, and a cooling system 130. The controller 110 allocates an amount of power from the power supply 120 between cooling mechanisms (e.g., fans 132, 142, 152) in the cooling system 130. In the event that not enough power is available to run every cooling mechanism at full power (e.g., during a power sag or heavy device usage), the controller 110 prioritizes available power for the cooling system 130 as necessary to prevent overheating of apparatus 100 components. The prioritization is performed based on predictive methods and monitored temperatures within the apparatus 100, with priority placed on providing more power to cooling mechanisms in zones of the apparatus 100 that may exceed their maximum allowed temperatures soonest.

[0021] In some examples, the cooling system 130 is an active cooling system. That is, it involves the use of power to cool the apparatus 100, as opposed to passive cooling that uses no power. In the example of FIG. 1, the active cooling mechanisms within the cooling system 130 are fans 132, 142, 152, which receive electrical power from the power supply 120 in order to drive an electric motor. In other examples, the cooling system 130 can include other active cooling mechanisms, such as pumps and chillers to transfer various liquids and gasses throughout the apparatus 100. Therefore, although cooling margin power management is described with respect to fans, methods and techniques described can also be applied to other types of active cooling mechanisms. In addition to active cooling, the cooling system 130 and other components of the apparatus 100 can make use of passive cooling elements (e.g., heatsinks).

[0022] In the example illustrated, the cooling system 130 includes cooling mechanism controls (131, 141, 151), fans (132, 142, 152), and temperature sensors (133, 143, 153). Although three sets of cooling components are shown, the cooling system 130 can comprise fewer or a greater number of sets of cooling components as necessary to provide adequate cooling for the apparatus 100. In further aspects, the cooling system 130 can include unequal numbers of controls, fans, and sensors. For example, temperature sensor 133 may measure the temperature of a zone served by fan 132 and another fan not illustrated. In another example, control 131 may regulate power available to fan 132 and another fan not illustrated.

[0023] In some aspects, the cooling mechanism controls 131, 141, 151 are electrical components or combinations of electrical components (e.g., switches, relays, resistors, transistors, servos, etc.) that the controller 110 can signal, program, or otherwise manipulate to adjust the power available to each of the fans 132, 142, 152. In one aspect, each of the fans 132, 142, 152 is electrically coupled to a control 131, 141, 151 that regulates the voltage, current, and/or resistance between the power supply 120 and its corresponding fan in order to enable, disable, or throttle the fan . In other aspects, the controls 131, 141, 151 are integrated into the fans themselves, and therefore the controller 110 transmits signals directly to the fan in order to control the fan motor.

[0024] In some aspects, the controller 110 can throttle the fans 132, 142, 152 so they provide less cooling but consume less power. In one example, the controls 131, 141, 151 are linear controls that the controller 110 uses to vary the voltage applied to the fan. For lower speeds (and less cooling) the voltage is decreased, and for higher speed it is increased. In another example, the fans 132, 142, 152 support pulse width modulation, in which the average value of the voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast rate. The longer the switch is on compared to the off periods, the higher the total power supplied to the load.

[0025] The controller 110, which is a programmable logic controller or other computing device, implements cooling margin power management within the apparatus 100. The controller 110 is coupled to components of the cooling system 130, including the controls 131, 141, 151 and temperature sensors 133, 143, 153. The controller 110 monitors or periodically receives temperature readings from each of the temperature sensors 133, 143, 153 disposed within the apparatus. In addition, the controller 110 can monitor or periodically receive power status and speed (i.e., revolutions per minute (RPMs)) of each of the fans 132, 142, 152, either directly from the fans or through their respective controls 131, 141, 151.

[0026] In some aspects, the controller 110 stores a maximum temperature allowed for each of the temperature sensors 133, 143, 153. These maximum temperatures can be based on thermal properties and rated operating specifications of components located proximate to the sensors within the apparatus 100, for example, within the same cooling zone. In some examples, components can report their maximum allowed

temperatures to the controller 110. In other examples, the controller 110 is pre-programmed with maximum allowed temperatures for each of the temperature sensors 133, 143, 153 or cooling zones.

[0027] Based on the actual temperature readings from the temperature sensors 133, 143, 153 and the maximum temperatures allowed, the controller 110 allocates power from the power supply 120 to the cooling system 130 in order to cool the apparatus 100. In one aspect, for each of the cooling zones, the controller 110 computes a difference between the actual temperature reading and the maximum temperature allowed. The controller 110 divides the difference by the thermal rate of change for the zone to compute the zone cooling margin, which represents an estimated amount of time before the actual temperature within the zone reaches or exceeds the maximum allowed temperature. The controller 110 ranks each of the zones based on their respective cooling margins, placing higher priority ranks on zones with lower cooling margins (fewest remaining seconds before

maximum temperature reached). Using the ranked list, the controller 110 prioritizes available power from the power supply 120 to operate the fans 132, 142, 152.

[0028] In one aspect, the controller 110 allocates a programmed, fixed amount of power (e.g., 500 watts) for the cooling system 130 between the fans 132, 142, 152 during typical use. However, this fixed amount of power may be insufficient to operate the fans 132, 142, 152 at full speed

simultaneously. Therefore, the controller 110 turns off or throttles fans ranked as the lowest priorities until the total power draw for the cooling system 130 is below the fixed amount of power.

[0029] Based on a minimum pace interval, the controller 110

recalculates cooling margins, re-ranks each of the cooling zones, and reallocates power within the cooling system 130. As fans are turned off and their corresponding zones see temperatures rise due to reduced airflow, the rank orders naturally change, resulting in the controller 110 turning off running fans in order to free up power to turn on fans which were previously disabled.

[0030] FIG. 2 illustrates an example printer with a housing divided into cooling zones. In the example illustrated, various printer components 244, 254, 264, 266 and cooling system components (fans 232, 242, 252, 262 and temperature sensors 233, 243, 253, 263) are disposed within physically, spatially, or thermally isolated zones 235, 245, 255, 265 within the housing 205. In some examples, fans 232, 242, 252, 262 remove waste heat generated by components 244, 254, 264, 266 of the printer 200 or introduce cooler air to the printer housing 205. Temperature sensors 233, 243, 253, 263 are located in each zone 235, 245, 255, 265 to report the zone temperature to the controller 210, and the controller 210 calculates cooling margins for the zones based on the temperatures, a threshold temperature for each zone, and a thermal rate of change for that zone. The controller determines whether to enable, disable, or throttle the fans 232, 242, 252, 262 disposed to transfer heat from each zone 235, 245, 255, 265 based on a comparison of the cooling margins calculated for each of the zones.

[0031] In some examples, the housing 205 within the printer 200 includes structural elements (represented by dashed lines in FIG. 2) that isolate each of the zones 235, 245, 255, 265 in which electrical and mechanical components 244, 254, 264, 266 of the printer 200 are retained. Thermal isolation at least partially restricts heat from passing between the zones. Thermal isolation can be accomplished with structures made up of an air dam, a plastic rib, a baffle, foam, gaskets, or any combination or layers of these. Physical and spatial isolation can be accomplished with similar structures or simply by providing empty space within the housing 205. In some aspects, airflow within the housing 205 can result in sufficient spatial isolation for zones to be considered thermally isolated.

[0032] Fans within the housing 205 can be positioned to create airflow through the housing 205 and remove waste heat generated by the various components. In addition, the housing 205 may include intake fans to draw cooler air from outside the printer 200 into the cooling zones. The airflow passing over the components can therefore include both outside and inside air to cool the components. Since the components heat up while in use, air at ambient room temperature may be sufficient to ensure that the components do not overheat. The resulting airflow may be expelled from the printer using fans, vents, or ducts.

[0033] In some examples, a single fan can serve multiple zones, or a single zone can contain multiple temperature sensors. In these examples, cooling margins for each zone can be based on a worst case prediction . That is, the controller 210 can rank each zone 235, 245, 255, 265 according to the lowest cooling margin (fewest remaining seconds before maximum

temperature reached) among the sensors.

[0034] FIG. 3 illustrates an example printer with a power monitor and controller to determine a total amount of power available to a cooling system. The power monitor 315 can periodically measure source voltage and current from the AC mains 312 to determine the amount of power available for the controller 310 to allocate between cooling mechanisms (e.g., fans) in the cooling system 330. In the event that not enough power is available to run every fan at full power (e.g., during a power sag or heavy usage), the controller 310 prioritizes available power between the cooling fans as necessary to prevent overheating of apparatus components, such as the mechanism motors 370, fusing lamp 380, and warming lamp 385. The prioritization is performed based on predictive methods and monitored temperatures of each cooling zone (or component) within the printer 300, with priority placed on fans in zones that may exceed their maximum allowed temperatures soonest.

[0035] The controller 310, which is a programmable logic controller or other computing device, implements cooling margin power management within the printer 300. The controller 310 is coupled to the cooling system 330 to monitor or periodically receive temperature readings from

temperature sensors within the printer 300. In addition, the controller 310 can monitor or periodically receive power status and speed (i.e., revolutions per minute (RPMs)) of each of the fans in the cooling system 330.

[0036] In some aspects, the controller 310 stores a maximum

temperature allowed for each of the temperature sensors. These maximum temperatures can be based on thermal properties and rated operating specifications of components (e.g., mechanism motors 370, fusing lamp 380, and warming lamp 385) located proximate to the sensors within the printer 300, for example, within the same cooling zone. In some examples, components can report their maximum allowed temperatures to the controller 310. In other examples, the controller 310 is pre-programmed with maximum allowed temperatures for each of the temperature sensors or cooling zones.

[0037] Based on the actual temperature readings from the temperature sensors and the maximum temperatures allowed, the controller 310 allocates power to the cooling system 330 in order to cool components within the printer 300. In one aspect, for each of the cooling zones, the controller 310 computes a difference between the actual temperature reading and the maximum temperature allowed. The controller 310 divides the difference by the thermal rate of change for the zone to compute the zone cooling margin, which represents an estimated amount of time before the actual temperature within the zone reaches or exceeds the maximum allowed temperature. The controller 310 ranks each of the zones based on their respective cooling margins, placing higher priority ranks on zones with lower cooling margins (fewest remaining seconds before maximum temperature reached). Using the ranked list, the controller 310 prioritizes available power to operate the fans in the cooling system 330.

[0038] In some aspects, the printer 300 includes a power monitor 315, which is an instrumentation circuit that measures the electrical current and voltage between the printer 300 and the AC mains 312 in order to calculate power usage for the printer 300. The power monitor 315 measures the aggregate sum of AC loads, both direct-AC (e.g., fusing lamp 380 and warming lamp 385) and AC that is converted to direct current (DC) by the AC/DC power supply units 320 for the mechanism motors 370 and cooling system 330. In one example, a single AC/DC PSU 320 powers the cooling system 330, while additional AC/DC PSUs 320 power critical DC loads such as the mechanism motors 370.

[0039] Based on the electrical current, voltage, and/or calculated power usage in the printer 300, the controller 310 can determine that a load reduction is needed to avoid tripping the circuit breaker. For example, if the circuit system for the printer 300 runs on 32 amps of current, and the power monitor 315 reports that the circuit is using 31.9 amps, the controller 310 can turn off or throttle fans ranked as the lowest priorities until the total power draw for the printer 300 reaches a programmed safety threshold, thus averting a possible shutdown without causing excessive thermal rise for any of the components within the printer 300.

[0040] In another example, the controller 310 can detect a sag on the AC line (due to AC line quality, product load transients, etc.) and use the electrical current, voltage, and/or calculated power usage in the printer 300 to determine how much load reduction is needed to avoid a shutdown. Using the ranked list, the controller 310 throttles or turns off a minimum number of fans sufficient to achieve the load reduction and avoid the shutdown until the line sag event has ended.

[0041] Based on a minimum pace interval, the controller 310

recalculates cooling margins, re-ranks each of the cooling zones, and reallocates power within the cooling system 330. As fans are turned off and their corresponding zones see temperatures rise due to reduced airflow, the rank orders naturally change, resulting in the controller 310 turning off running fans in order to free up power to turn on fans which were previously disabled. In some examples, if a line sag event persists, resulting in

insufficient power available to prevent one of the cooling zones from reaching its maximum temperature allowed, the controller 310 can trigger a system shutdown .

[0042] METHODOLOGY

[0043] FIGS. 4 through 7 are flow charts describing example methods used in cooling margin power management. Although some operations of the methods are described below as being performed by specific components of the apparatus and printers illustrated in FIGS. 1 through 3, these operations need not necessarily be performed by the specific components identified, and could be performed by a variety of components and modules, potentially distributed over a number of machines. Accordingly, references may be made to elements of the apparatus 100 and printers 200, 300 for the purpose of illustrating suitable components or elements for performing features of the methods being described. Alternatively, at least certain ones of the variety of components and modules described can be arranged within a single

hardware, software, or firmware component. Furthermore, some of the features of these methods may be performed in parallel or in a different order than illustrated.

[0044] FIG. 4 illustrates an example method for cooling in an apparatus. A controller for the apparatus allocates a fixed or measured amount of power between cooling mechanisms (e.g., fans) in the apparatus. In the event that not enough power is available to run every fan at full power (e.g., during a power sag or heavy device usage), the controller prioritizes available power between the cooling fans as necessary to prevent overheating of apparatus components. The prioritization is performed based on predictive methods and monitored temperatures of each cooling zone (or component) within the apparatus, with priority placed on fans in zones that may exceed their maximum allowed temperatures soonest.

[0045] In some implementations, the controller determines a total amount of power available for the cooling system of the apparatus (410). In one example, the controller allocates a programmed, fixed amount of power (e.g., 500 watts) for the cooling system between the fans during typical use. In other examples, the controller determines the total amount of power available from an instrumentation circuit that measures the electrical current and voltage between the apparatus and the AC mains.

[0046] The controller monitors or periodically receives temperature readings measured from temperature sensors disposed within the apparatus (420). Based on the actual temperature readings from the temperature sensors and the maximum temperatures allowed associated with the temperature sensors, the controller selectively operates the fans by allocating the total amount of power available to the cooling system between the fans in order to cool the apparatus (430).

[0047] FIG. 5A illustrates an example method for cooling margin power management. In some aspects, a controller for a printer is coupled to components of the printer cooling system, which includes temperature sensors disposed within physically, spatially, or thermally isolated cooling zones within a housing for the printer.

[0048] The controller monitors or periodically receives temperature readings from each of the temperature sensors for their respective cooling zones (510). In some aspects, the controller stores a maximum temperature allowed for each of the temperature sensors or their respective cooling zones. These maximum temperatures can be based on thermal properties and rated operating specifications of components located proximate to the sensors within the printer, for example, within the same cooling zone. Based on a comparison between the actual temperature readings, maximum

temperatures allowed, and temperature rates of change for each zone, the controller determines a zone cooling priority (520).

[0049] In some examples, the zone cooling priority is a list of zones ranked by urgency, with priority given to cooling zones that may exceed their maximum temperature allowed sooner without additional cooling. Thus, the controller can allocate power to the fans in accordance with the ranked zone cooling priority in order to efficiently cool the printer components (530).

[0050] FIG. 5B illustrates an example method for determining zone cooling priority. For each of the cooling zones, the controller compares the actual temperatures measured in the zone with the maximum temperature allowed for that zone (540). The controller further computes a difference between the actual temperature reading and the maximum temperature allowed.

[0051] In one aspect, the controller divides the difference by the thermal rate of change for the zone to compute the zone cooling margin, which represents an estimated amount of time before the actual temperature within the zone reaches or exceeds the maximum allowed temperature (550). The controller can determine the thermal rate of change for the zone and calculate the cooling margin using recent measurements for the temperature change. In other aspects, the controller can use historical data in order to create a model characterizing the relationship between the actual

temperature of the zone and its thermal rate of change, taking into account other factors such as electrical current, voltage, and power usage for the printer and components, fan power and speed, and the status of print jobs for the printer. Alternatively, the controller can include a pre-programmed model of thermal rates of change based on the printer configuration . The model can be static, or the controller can update the model with additional data collected during use.

Table 1 - cooling zones ranked by cooling margin

[0052] In one implementation, the controller can determine the thermal rate of change as an average rate of change of the actual temperatures measured over the last few seconds or minutes. For example, referring to Table 1, the actual temperature in Zone 1 is 30 degrees. Assuming that the actual temperature was 29 degrees when measured two seconds previously, the thermal rate of change (Thermal TC) is therefore 0.5 degrees/sec. Since the difference between the maximum temperature allowed for Zone 1 and the actual temperature is 70 degrees and the thermal rate of change is 0.5 degrees/sec, the cooling margin is 140 seconds. This implementation does not rely on any historical data or trends, and it can accommodate non-well- behaved systems where loads and/or temperatures vary unpredictably.

[0053] In another implementation, historical variations in actual temperatures for zones are used to create a model of the thermal rates of change, which is used to predict the cooling margin. For example, referring to Table 1, the actual temperature in Zone 2 is 25 degrees. Although the actual temperature may have been 23 degrees when measured two seconds previously, the model predicts that, based on historical data and current conditions, the temperature in Zone 2 should rise on average 0.2 degrees/sec from 25 degrees to the 80 degree maximum temperature allowed. Therefore the cooling margin for Zone 2 is 275 seconds. This implementation utilizes historical data for the model, which the controller can generate or update during use. The modelling approach accommodates well-behaved systems with predictable temperature changes, even if those changes are non-linear.

[0054] In a further implementation, the controller can employ a hybrid approach, wherein model-based projections are adjusted to account for actual conditions. In this implementation, thermal rates of change and cooling margins obtained from the model are compared with recent data in order to verify the accuracy of the model. The controller can update the model as necessary and adjust the cooling margin accordingly.

[0055] After calculating the cooling margin for a zone, the controller can determine whether there are any remaining zones left to calculate (560). If not, the controller ranks each of the zones based on their respective cooling margins, placing higher priority ranks on zones with lower cooling margins (fewest remaining seconds before maximum temperature reached) (570). Using the ranked list, the controller prioritizes available power to operate the fans.

[0056] FIG. 6 illustrates an example method for allocating power to a cooling system using a power monitor. In some aspects, the printer includes a power monitor, which is an instrumentation circuit that measures the electrical current and voltage between the printer and the AC mains in order to calculate power usage for the printer (610). The power monitor measures the aggregate sum of AC loads, both direct-AC and AC that is converted to DC by AC/DC power supply units.

[0057] Based on the electrical current, voltage, and/or calculated power usage in the printer, a controller can determine the power available for the cooling system (620). In some aspects, the controller can determine that a load reduction is needed to avoid tripping the circuit breaker. For example, if the circuit system for the printer runs on 32 amps of current, and the power monitor reports that the circuit is using 31.9 amps, the controller reallocate power to the fans in order to turn off or throttle fans ranked as the lowest priorities until the total power draw for the printer reaches a programmed safety threshold, thus averting a possible shutdown without causing excessive thermal rise for any of the components within the printer (630).

[0058] Based on a minimum pace interval, the controller recalculates cooling margins, re-ranks each of the cooling zones, and reallocates power within the cooling system. As fans are turned off and their corresponding zones see temperatures rise due to reduced airflow, the rank orders naturally change, resulting in the controller turning off running fans in order to free up power to turn on fans which were previously disabled.

[0059] FIG. 7 illustrates an example method for reallocating power in an apparatus. In some aspects, the controller detects that actual

temperatures within a cooling zone are at or above a programmed threshold (710). For example, there may be insufficient power available to prevent one of the cooling zones from running out of cooling margin and reaching its maximum temperature allowed, even with cooling margin power

management. This could be due to a persistent line sag event resulting in an extended period of insufficient voltage or current available to the printer.

[0060] In some aspects, rather than shut the system down, the controller can reduce the process speed or otherwise reduce performance of components (720). For example, in a printer, the controller can reduce the speed of mechanism motors in order to slow down the printing process, thus lowering the power requirements to continue printing. As a result, the controller can increase the power available to the cooling system fans in order to reduce temperatures below the programmed thresholds and increase cooling margins (730). [0061] Upon determining that temperatures or cooling margins have returned to safe levels, the controller can resume normal operation of the printer and disable or throttle fans as needed.

[0062] In further aspects, the controller determines whether to disable or throttle fans based on a determination that at least one of the printer components is receiving insufficient power. For example, during a line sag event, the total amount of power available may not be sufficient for the printer components to operate while the cooling system is active, and therefore the controller can disable cooling system fans to free up additional power for critical loads.

[0063] Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.

Therefore, it is intended that aspects described be limited only by the claims and the equivalents thereof.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising :

a cooling system comprising :

a plurality of active cooling mechanisms; and

a plurality of temperature sensors; and

a controller operatively connected to the cooling system to:

selectively operate each of the plurality of active cooling mechanisms based on a total amount of power available to the cooling system and temperatures measured by the plurality of temperature sensors.

2. The apparatus of claim 1, further comprising :

a housing divided into a plurality of zones, each of the plurality of zones at least partially thermally isolated from each other; and

a plurality of electrical components disposed within the housing.

3. The apparatus of claim 2, wherein the active cooling mechanisms are fans that transfer heat generated by the electrical components.

4. The apparatus of claim 2, wherein each of the plurality of temperature sensors are disposed within at least one of the plurality of zones and each of the plurality of active cooling mechanisms are disposed to transfer heat from at least one of the plurality of zones.

5. The apparatus of claim 4, wherein the controller selectively operates each of the plurality of active cooling mechanisms by allocating the total amount of power available between the active cooling mechanisms in order to enable, disable, or throttle each of the active cooling mechanisms.

6. The apparatus of claim 5, wherein the controller determines whether to disable or throttle the active cooling mechanisms based on a determination that at least one of the plurality of electrical components is receiving insufficient power.

7. The apparatus of claim 5, wherein the controller determines whether to enable, disable, or throttle the active cooling mechanisms disposed to transfer heat from each zone based on a comparison of cooling margins calculated for each of the plurality of zones.

8. The apparatus of claim 7, wherein the controller calculates the cooling margins for each zone based on the temperatures measured by the temperature sensors disposed within that zone, a threshold temperature for that zone, and a temperature rate of change for that zone.

9. The apparatus of claim 8, wherein the controller reduces performance of at least some of the plurality of electrical components based on the cooling margins.

10. The apparatus of claim 1, further comprising :

a power monitor to periodically measure electric current and voltage in the apparatus, the controller to determine the total amount of power available to the cooling system based on either the electric current or the voltage measured.

11. The apparatus of claim 1, wherein the total amount of power available is a predetermined number of watts.

12. A printer comprising :

a housing divided into a plurality of zones, each of the plurality of zones at least partially thermally isolated from each other;

a plurality of electrical components disposed within the housing;

a cooling system comprising :

a plurality of active cooling mechanisms disposed to transfer heat from at least one of the plurality of zones; and

a plurality of temperature sensors disposed within at least one of the plurality of zones; and

a controller operatively connected to the cooling system to:

selectively operate each of the plurality of active cooling mechanisms based on a total amount of power available to the cooling system and temperatures measured by the plurality of temperature sensors for each of the plurality of zones.

13. The printer of claim 12, wherein the controller selectively operates each of the plurality of active cooling mechanisms by allocating the total amount of power available between the active cooling mechanisms in order to enable, disable, or throttle each of the active cooling mechanisms.

14. The printer of claim 13, wherein the controller determines whether to enable, disable, or throttle the active cooling mechanisms disposed to transfer heat from each zone based on a comparison of cooling margins calculated for each of the plurality of zones.

15. A method for cooling in an apparatus, the method comprising :

determining a total amount of power available to a plurality of active cooling mechanisms;

measuring temperatures within the apparatus with a plurality of temperature sensors; and

selectively operating each of the active cooling mechanisms based on the total amount of power available and the temperatures.