Fan control apparatus and fan control method for computer equipment

A fan control apparatus is provided for the computer equipment including a fan, a temperature sensor, and a device module (e.g. an add-in card) mounting at least two devices aligned along an air flow. The fan control apparatus determines a revolving speed of the fan for cooling each device based on an inlet temperature and a usage rate of each device. In addition, the fan control apparatus estimates an inlet temperature of a second device, which is disposed in the downstream side of a first device among at least two devices, based on an inlet temperature and a usage rate of the first device. Thus, it is possible to control the fan to cause an adequate amount of cooling air for cooling devices mounted on the device module installed in the computer equipment.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the priority benefit of Japanese Patent Application No. 2016-59497 filed on Mar. 24, 2016, the subject matter of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to computer equipment having a cooling fan to cool an inlet air and/or an outlet air. In particular, the present invention relates to a fan control apparatus and a fan control method for controlling the revolving speed of a cooling fan depending on an internal temperature of computer equipment.

2. Description of Related Art

Generally, computer equipment has its casing equipped with a cooling fan to control a temperature increase due to the heating of devices installed therein. For example, it is possible for the computer equipment to employ the generally-known methods for controlling the operation of a cooling fan as follows.(1) A temperature sensor is attached to a device inside the computer equipment so as to monitor its temperature, and therefore the computer equipment controls the revolving speed of a cooling fan based on the temperature.(2) The computer equipment monitors the temperature of an inlet air flowing into a device, and therefore the computer equipment controls the revolving speed of a cooling fan based on the inlet temperature.(3) The computer equipment monitors a current or power applied to a device while monitoring an inlet temperature so as to estimate the temperature status of a device, and therefore the computer equipment controls the revolving speed of a cooling fan based on the inlet temperature and the current applied to a device.

Conventionally, computer systems are equipped with cooling devices, which are disclosed in documents, namely patent literatures (PLT) or patent documents. For example, PLT 1 discloses a cooling device for a server having a processor and a fan. The temperature of a processor after a predetermined time elapses is estimated based on the current temperature and the operating ratio of a process as well as the revolving speed of a fan and the inlet temperature of a server, and therefore the cooling fan is controlled to operate at target revolving speed when the estimated temperature exceeds a predetermined value. PLT 2 discloses a dynamic revolution control device for a cooling fan installed in a computer having first and second devices. A table is provided to store the relationship between the temperature of a computer, the temperature of a first device, the temperature of a second device, and the revolving speed of a cooling fan, and therefore the revolving speed of a cooling fan is determined with reference to the table. PLT 3 discloses a computer system equipped with a battery-mounted system board and a cooling fan. The computer system changes the operating state of a cooling fan depending on whether or not a battery is being charged, and therefore the computer system prevents a temperature increase inside the casing due to heating of a battery being charged. PLT 4 discloses a cooling method for an electronic device. The electronic device controls the cooling degree of a cooling member depending on the attribute of an extension card attached thereto.

The foregoing methods (1) to (3) suffer from the following drawbacks. It is likely that the method (1) cannot optimally control a cooling fan with respect to a device unable to accept a temperature sensor attached thereto. The method (2) may not actually monitor the temperature status of a device; hence, in the worst case scenario (where a device operates with the maximum power), it may operate a cooling fan at extremely high speed. The method (3) may not appropriately control the temperature of each device with respect to an add-in card including multiple devices having different temperature statuses. The foregoing technologies (e.g. PLT 1, PLT 2, and PLT 4) suffer from those drawbacks. PLT 3 is limited to a battery as a cooling object; hence, it is difficult to apply the technology of PLT 3 to other types of devices.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

The present invention aims to provide a fan control apparatus and a fan control method for appropriately controlling the revolving speed of a cooling fan depending on the temperature status of each device in the computer equipment.

In a first aspect of the invention, a fan control apparatus is provided for the computer equipment including at least two devices aligned along an air flow caused by a fan. The fan control apparatus includes a fan revolving speed determination part configured to determine the revolving speed of a fan for cooling each device based on an inlet temperature and a usage rate of each device, and a temperature estimation part configured to estimate an inlet temperature of a second device, which is disposed in the downstream side of a first device among at least two devices, based on the inlet temperature and the usage rate of the first device.

In a second aspect of the invention, a fan control system is provided for the computer equipment including at least two devices aligned along an air flow. The fan control system includes a fan causing an air flow inside the computer equipment, and a fan control apparatus configured to control the revolving speed of a fan for cooling each of at least two devices aligned along an air flow caused by a fan. The fan control apparatus estimates an outlet temperature of a first device, which is disposed in the upstream side among at least two devices, as an inlet temperature of a second device, which is disposed in the downstream side among at least two devices, based on the inlet temperature and the usage rate of the first device. In addition, the fan control apparatus determines the revolving speed of a fan for cooling each device based on the inlet temperature and the usage rate of each device.

In a third aspect of the invention, computer equipment includes a device module including at least two devices aligned along an air flow, a temperature sensor configured to measure an inlet temperature of the device module, a fan configured to cause an air flow for cooling each device in the device module, a storage unit including a temperature estimation table and a fan control table, and a fan control apparatus configured to control the revolving speed of a fan for cooling each device with reference to the temperature estimation table and the fan control table. As at least two devices, a first device is disposed in the upstream side of an air flow while a second device is disposed in the downstream side of an air flow. The temperature estimation table stores an outlet temperature of each device in correspondence with an inlet temperature and a usage rate of each device while the fan control table stores the revolving speed of a fan in correspondence with the inlet temperature and the usage rate of each device. The fan control apparatus estimates the outlet temperature of the first device as the inlet temperature of the second device with reference to the temperature estimation table using the inlet temperature and the usage rate of the first device. In addition, the fan control apparatus determines the revolving speed of a fan for cooling each device with reference to the fan control table using the inlet temperature and the usage rate of each device.

In a fourth aspect of the invention, a fan control method is provided for the computer equipment including at least two devices aligned along an air flow caused by a fan. As at least two devices, a first device is disposed in the upstream side of an air flow while a second device is disposed in the downstream side of an air flow. The fan control method includes the steps of: determining the revolving speed of a fan for cooling each device based on the inlet temperature and the usage rate of each device; and estimating the inlet temperature of the second device based on the inlet temperature and the usage rate of the first device. In this connection, it is possible to provide a non-transient computer-readable storage medium storing a program causing a computer serving as a fan control apparatus to implement the fan control method.

According to the present invention, it is possible to control a fan at optimum revolving speed depending on the temperature status inside the computer equipment which does not necessarily provide a temperature sensor for each of multiple devices mounted on a device module (e.g. an add-in card). Thus, it is possible to appropriately cool each device mounted on the device module at high efficiency by causing an adequate amount of cooling air depending on the temperature status of each device on the device module.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be described in detail by way of examples with reference to the accompanying drawings, wherein the same parts shown in different drawings are denoted using the same reference signs; hence, the detailed descriptions thereof will be omitted as necessary.

FIG. 1is a block diagram showing the minimum configuration of a fan control apparatus10according to the embodiment of the present invention. The fan control apparatus10includes a temperature estimation part131and a fan revolving speed determination part132.

The fan control apparatus10is designed control the revolving speed of a fan configured to cause an air flow for cooling a device. The temperature estimation part131estimates the temperature in the downstream of a device (i.e. a downstream temperature of a device) based on the temperature in the upstream of a device (i.e. an upstream temperature of a device) and an operating state of a device. This estimation can be applied to two devices that are aligned along a cooling air caused by a fan, namely an upstream device and a downstream device. That is, it is possible for the temperature estimation part131to estimate the upstream temperature of a downstream device based on the upstream temperature of an upstream device and the operating state of an upstream device.

The fan revolving speed determination part132determines the revolving speed of a fan configured to cool a device based on the upstream temperature of a device and the operating state of a device. This determination can be applied to two devices that are aligned along a cooling air caused by a fan, namely an upstream device and a downstream device. That is, it is possible for the fan revolving speed determination part132to determine the revolving speed of a fan suited to an upstream device based on the upstream temperature of an upstream device and the operating state of an upstream device. In addition, it is possible for the fan revolving speed determination part132to determine the revolving speed of a fan suited to a downstream device based on the upstream temperature of a downstream device estimated by the temperature estimation part131and the operating state of a downstream device.

1. First Embodiment

FIG. 2is a block diagram of computer equipment100implementing a fan control system according to the first embodiment of the present invention. The computer equipment100includes a fan1, a CPU2, a temperature sensor3, a device module6, and a fan control apparatus10in casing thereof. A pair of devices5a,5bare mounted on the device module6. The device module6is detachably attached to the casing of the computer equipment100. In addition, the devices5a,5bare detachably attached to the device a module6. For example, the device module6is an add-in card. In this case, the devices5a,5bare integrated circuit components mounted on the add-in card. The fan control system may embrace at least the fan1and the fan control device10.

The fan1is a cooling fan configured to decrease the temperature inside the casing of the computer equipment100. InFIG. 2, arrow symbols A1through A4indicate an air flow caused by the fan1. That is, revolving the fan1causes an air flow from the left to the right on the drawing sheet ofFIG. 2. This air flow may cool the CPU2, the devices5a,5b, the device module6, and the like. The temperature sensor3is provided to check the temperature status inside the casing of the computer equipment100. The fan control apparatus10controls the revolving speed of the fan based on the temperature information measured by the temperature sensor3so as to control the inside temperature of the casing, e.g. the temperature in the surrounding area of the devices5a,5band the device module6that may cause heat due to the operation of the computer equipment100. In this connection, the configurations and arrangements of devices installed in the casing of the computer equipment100are not necessarily limited to those shown inFIG. 2. However, the temperature sensor3should be positioned in the upstream of any device that may affect the air temperature (which is an object to be controlled by the present embodiment). In other words, the temperature sensor3should be located on the windward of an air flow, e.g. the left-side on the drawing sheet ofFIG. 2. Due to the positional relationship between the temperature sensor3and the device module6shown inFIG. 2, it is possible to measure an intake temperature4aof the device5a(i.e. the temperature of an air flow in the direction A2) based on the measured temperature of the temperature sensor3. Herein, the term “intake temperature” is the temperature of an air adjoining the upstream of any device. Reference sign4bdenotes an intake temperature of the device5b, i.e. the temperature of an air flow in the direction A3. In addition, the arrow symbol A4denotes an outlet air (or an exhaust air) output from the computer equipment100. In this connection, the term “outlet temperature” is the temperature of an air adjoining the downstream of any device. In general, it is possible to control the revolving speed of the fan1based on the intake temperature of any device.

In the case ofFIG. 2where the device module6includes a plurality of devices5a,5b, it is possible to position the temperature sensor3in the upstream of the device module6, but it is difficult to position the temperature sensor3in the downstream of the device5aand in the upstream of the device5b. In this case, it is possible to estimate that the device5bmay be exposed to the highest temperature irrespective of the intake temperature4band the operating state of the device5b, and therefore it is possible to control the revolving speed of the fan1in conformity with the temperature status of the device5b. However, this temperature control method may have a room of improvement in terms of the power saving and the noise reduction. The present embodiment is able to estimate the temperature status, which may differ for each device, even when it is impossible to provide temperature sensors for multiple devices, thus optimally control the revolving speed of a fan.

FIG. 3is a block diagram showing the internal configuration of the fan control apparatus10according to the first embodiment of the present invention, wherein the same parts as those shown inFIGS. 1 and 2are denoted using the same reference signs; hence, the detailed descriptions thereof will be omitted here. The fan control apparatus10includes a temperature acquisition part11, a device usage rate acquisition part12, a controller13, a fan revolving speed controller14, and a storage unit15.

The temperature acquisition part11acquires the temperature information measured by the temperature sensor3.

The device usage rate acquisition part12acquires the usage rates (representing the operating states) of the devices5a,5bpositioned in the downstream of the temperature sensor3by way of a device usage rate management software20. The device usage rate management software20is the software executed on the operating system (OS) running with the computer equipment100. That is, the device usage rate management software20is the software that monitors and manages the usage rate of each device (e.g. a video chip) utilized by the OS and its application. In particular, the device usage rate management software20has a function to monitor the usage rates of the devices5a,5bmounted on the device module6shown inFIG. 2.

The controller13controls the revolving speed of the fan1based on the temperature information acquired by the temperature acquisition part11and the usage rate information acquired by the device usage rate acquisition part12. The controller13further includes the temperature estimation part131and the fan revolving speed determination part132, both of which have been already described in conjunction withFIG. 1. Specific applications of those parts131-132will be described in conjunction withFIG. 2. The temperature estimation part131acquires the temperature information measured by the temperature sensor3(which is installed in the casing of the computer equipment100) and the usage rate of the device5a(referred to as a first device) positioned in the downstream of the temperature sensor3so as to estimate the temperature of an air in the downstream of the device5a. The fan revolving speed determination part132determines the revolving speed (referred to as first revolving speed) of the fan1suited to cooling of the device5abased on the temperature information of the temperature sensor3and the usage rate of the device5a. In addition, the fan revolving speed determination part132determines the revolving speed (referred to as second revolving speed) of the fan1suited to cooling of the device5b(referred to as a second device) based on the estimated temperature of the temperature estimation part131and the usage rate of the device5b(which is positioned in the downstream of the device5a). Subsequently, the fan revolving speed determination part132selects a higher value between the first and second revolving speeds so as to determine the selected revolving speed for the fan1.

The fan revolving speed controller14operates the fan1at the revolving speed determined by the fan revolving speed determination part132.

The storage unit15stores various pieces of information needed to control the fan1. For example, the storage unit15stores a temperature estimation table151(which is used for estimation of the air temperature in the downstream of the device5a(i.e. the first device) by the temperature estimation part151) and a fan control table152(which is used for determination of the revolving speed of the fan1by the fan revolving speed determination part132). These tables151,152will be discussed with reference toFIGS. 4 to 6.

FIG. 4shows an example of the temperature estimation table151, i.e. a temperature estimation table151a, stored in the storage unit15. The temperature estimation table151ahas three items, namely “inlet temperature (4a)”, “usage of device5a”, and “inlet temperature (4b)”. The temperature at the air-inlet side of the device module6(i.e. the inlet temperature4a) shown inFIG. 2is registered in the item “inlet temperature (4a)” of the temperature estimation table151a. InFIG. 2, no device (or no member) causing heat is interposed between the temperature sensor3and the device module6. Therefore, the measured temperature of the temperature sensor3can be used for the inlet temperature4a. In addition, no heating member is disposed in the upstream of the device5amounted on the device module6. Therefore, the measured temperature of the temperature sensor3can be used for the inlet temperature4a. In this connection, the inlet temperature4acorresponds to the temperature of an inlet air flowing into the device5a.

In the temperature estimation table151a, the item “usage rate of device5a” describes various ranges of usage rates. It is possible to acquire the usage rate of the device5aby way of the device usage rate management software20.

The outlet temperature of the device5a(i.e. the inlet temperature4b) is registered in the item “inlet temperature (4b)” of the temperature estimation table151a. InFIG. 2, the inlet temperature4bof the device5bcorresponds to the outlet temperature of the device5a. The device5ais subjected to high temperature as the usage rate of the device5abecomes higher; hence, the outlet temperature of the device5a(i.e. the inlet temperature4bof the device5b) becomes higher. This indicates that the inlet temperature4bof the device5bis correlated to the inlet temperature4aof the device5aand the usage rate of the device5a. In other words, it is possible to calculate the inlet temperature4bby way of desk calculation and actual machine simulation in advance. For this reason, pre-calculated values as the inlet temperature4bare registered in the item “inlet temperature (4b)”.

Using the temperature information measured by the temperature sensor3and the usage rate of the device5aacquired by the device usage rate acquisition part12, the temperature estimation part131reads the outlet temperature of the device5a(i.e. the inlet temperature4b) from the temperature estimation table151ashown inFIG. 4. On the condition that the temperature sensor3measures the temperature information of 30° C. while the device usage rate acquisition part151acquires the usage rate 38% of the device5a, for example, the temperature estimation part131retrieves the corresponding data (or record) from the temperature estimation table151using the item of “inlet temperature (4a)” at 30° C. and the item of “usage rate of device5a” at 38%, thus reading the corresponding value (i.e. 35° C.) as the item of “inlet temperature (4b)” from the storage unit15. Thus, it is possible to obtain the inlet temperature4bof the device5beven when no temperature sensor is attached to the device5b.

FIG. 5shows an example of the fan control table152, i.e. a fan control table152a, stored in the storage unit15. The fan control table152aofFIG. 5is the table used for calculating the revolving speed of the fan1suited to the temperature status of the device5a. InFIG. 5, the fan control table152ahas three items, namely “inlet temperature (4a)”, “usage rate of device5a”, and “revolving speed of fan1”. Various ranges for the inlet temperature4aof the device module6are registered in the item “inlet temperature (4a)”. Various ranges for the usage rate of the device5aare registered in the item of “usage rate of device5a”. Various values for the revolving speed of the fan1are registered in the item of “revolving speed of fan1”. For example, the revolving speed of the fan1suited to the temperature status of the device5acan be defined as the minimum revolving speed in the range of revolving speed for maintaining the temperature range of the device5awhich would not badly affect the operation and the lifetime of the device5awhen the fan1operates at the revolving speed. This revolving speed of the fan1can be obtained by way of desk calculation and actual machine simulation and set to the fan control table152a. The fan control table152ashows that the item of “revolving speed of fan1” is correlated to the item of “inlet temperature (4a)” and the item of “usage rate of device5a”. This derives from the assumption that the temperature status of the device5awould be correlated to the temperature of an inlet air blown to the device5a(i.e. the inlet temperature4a) and the usage rage of the device5a. It is necessary to cool the device5aby increasing the revolving speed of the fan1since the temperature of the device5abecomes higher as the usage rage of the device5abecomes higher.FIG. 5shows an example of the fan control table152afor the device5a, and therefore the fan control table152ashows increasing values of the revolving speed of the fan1as the usage rate of the device5abecomes higher. According to the fan control table152aofFIG. 5, the revolving speed of the fan1is increased to be higher as the inlet temperature4aof the device5abecomes higher when the usage rate of the device5arests on the same range.

Using the temperature information measured by the temperature sensor3and the usage rate of the device5aacquired by the device usage rate acquisition part12, the fan revolving speed determination part132reads the revolving speed of the fan1suited to cooling of the device5afrom the fan control table152a. On the condition that the temperature information of the temperature sensor3is 32° C. while the usage rate of the device5aacquired by the device usage rate acquisition part12is 55%, for example, the fan revolving speed determination part132retrieves the corresponding data (or record) from the fan control table152ausing the item of “inlet temperature (4a)” at 32° C. and the item of “usage rate of device5a” at 55%, thus reading the corresponding value (i.e. 6,500 rpm) as the item of “revolving speed of fan1” from the storage unit15. Thus, it is possible to maintain the temperature of the device5ain an appropriate temperature range. In addition, it is possible to determine the revolving speed of the fan1(i.e. the first revolving speed) which may achieve low cost and save power.

FIG. 6shows another example of the fan control table, i.e. a fan control table152b, stored in the storage unit15. The fan control table152bofFIG. 6is the table for calculating the revolving speed of the fan1suited to the temperature status of the device5b. The fan control table152bhas three items, namely “inlet temperature (4b)”, “usage rate of device5b”, and “revolving speed of fan1”. Various ranges for the inlet temperature4bof the device5bare registered in the item of “inlet temperature (4b)”. Herein, the inlet temperature4bof the device5bcorresponds to the outlet temperature of the device5a. Various ranges for the usage rate of the device5bare registered in the item of “usage rate of device5b”. Various values for the revolving speed of the fan1suited to the temperature status of the device5bare registered in the item of “revolving speed of fan1”. Similar to the fan control table152aofFIG. 5, the fan control table152bofFIG. 6describes the minimum revolving speed of the fan in the range of revolving speed of the fan1suited to cooling of the device5b(i.e. the second device) which is calculated by way of desk calculation and actual machine simulation. The fan control table152bshows that values of “revolving speed of fan1” are set in correlation with ranges of “inlet temperature (4b)” and ranges of “usage rate of device5b”. This derives from the assumption that the temperature status of the device5bwould be correlated to the downstream temperature of the device5a(i.e. the outlet temperature of the device5a) and the operating rate of the device5b. It is necessary to cool the device5bby increasing the revolving speed of the fan1since the temperature of the device5bbecomes higher as the usage rate of the device5bbecomes higher.FIG. 6shows an example of the fan control table152bfor the device5b, wherein the fan control table152bdescribes values for the revolving speed of the fan1which are increased as the usage rate of the device5bbecomes higher. According to the fan control table152b, the revolving speed of the fan1is increased to be higher as the inlet temperature4bof the device5bbecomes higher when the usage rate of the device5brests on the same range.

Using the temperature information estimated by the temperature estimation part131and the usage rate of the device5bacquired by the device usage rate acquisition part12, the fan revolving speed determination part132obtains the revolving speed of the fan1suited to cooling of the device5bfrom the fan control table152bofFIG. 6. On the condition that the temperature estimation part131estimates the inlet temperature4bof the device5b(or the outlet temperature of the device5a) at 34° C. while the device usage rate acquisition part12acquires the usage rate of the device5bat 80%, for example, the fan revolving speed determination part132retrieves the corresponding data (or record) from the fan control table152busing the inlet temperature4bof 34° C. and the usage rate 80% of the device5b, thus reading the corresponding value (i.e. 7,000 rpm) as the item of “revolving speed of fan1” from the storage unit15. Thus, it is possible to maintain the temperature of the device5bin an appropriate temperature range. In addition, it is possible to obtain the revolving speed of the fan1(i.e. the second revolving speed) achieving low cost and power saving.

The fan revolving speed determination part132selects a higher value between the first revolving speed of the fan1suited to cooling of the device5aand the second revolving speed of the fan1suited to cooling of the device5b. By selecting higher revolving speed, it is possible for the fan1to cause an adequate amount of air flow for cooling both the devices5aand5b.

FIG. 7is a flowchart showing a fan revolving speed determination process according to the first embodiment of the present invention. Now, the process for determining the revolving speed of the fan1will be described with reference to the flowchart ofFIG. 7.

The fan revolving speed determination process will be carried out on the precondition that the temperature sensor3measures the temperature information at a predetermined time interval so as to send the measured temperature information to the temperature estimation part131. Upon receiving an instruction of the device usage rate acquisition part12, the device usage rate management software20measures the usage rates of the devices5a,5bat a predetermined time interval so as to send their usage rates to the device usage rate acquisition part12.

First, the temperature estimation part131acquires the inlet temperature4aof the device5afrom the temperature sensor3(step S11). The temperature estimation part131sends the inlet temperature4ato the controller13. In the controller13, the temperature estimation part131receives the inlet temperature4a.

Next, the device usage rate acquisition part12acquires the usage rates of multiple devices (e.g. the devices5a,5b) from the device usage rate management software20(step S12). The device usage rate acquisition part12sends the usage rates of the devices5a,5bto the controller13. In the controller13, the temperature estimation part131receives the usage rate of the device5a. In addition, the fan revolving speed controller132receives the usage rates of the devices5a,5b.

Next, the temperature estimation part131estimates the inlet temperature of the device5bbased on the inlet temperature4aof the device5aand the usage rate of the device5a(step S13). Specifically, the temperature estimation part131reads the inlet temperature4bof the device5b, which is correlated to the inlet temperature4aand the usage rate of the device5a, from the temperature estimation table151aof the storage unit15. The temperature estimation part131sends the read inlet temperature4bto the fan revolving speed determination part132.

Next, the fan revolving speed determination part132determines the revolving speed of the fan1based on the usage rates of the devices5a,5b(step S14). First, the fan revolving speed determination part132determines the revolving speed of the fan1(i.e. the first revolving speed). Specifically, the fan revolving speed determination part132reads the revolving speed of the fan1, which is correlated to the inlet temperature4aand the usage rate of the device5a, from the fan control table152aof the storage unit15shown inFIG. 5. The read revolving speed indicates the first revolving speed. In addition, the fan revolving speed determination part132determines the revolving speed of the fan1(i.e. the second revolving speed). Specifically, the fan revolving speed determination part132reads the revolving speed of the fan1, which is correlated to the inlet temperature4band the usage rate of the device5b, from the fan control table152bof the storage unit15shown inFIG. 6. The read revolving speed indicates the second revolving speed.

Next, the fan revolving speed determination part132selects the highest revolving speed between the first and second revolving speeds, thus determining the optimum revolving speed of the fan1(step S15). Specifically, the fan revolving speed determination part132compares the first and second revolving speeds so as to select a higher value. The selected revolving speed indicates the optimum revolving speed of the fan1. The fan revolving speed determination part132sends the selected revolving speed of the fan1to the fan revolving speed controller14. The fan revolving speed controller14controls the fan1such that its revolving speed will match the revolving speed determined by the fan revolving speed determination part132. Thereafter, the fan control apparatus10repeats a series of steps S11to S15so as to control the revolving speed of the fan1.

In the computer equipment100ofFIG. 2that prevents a temperature sensor from being attached to the device module6(e.g. an add-in card), it is uncertain to determine the temperature of the device5a, the temperature of the device5b, and the inlet temperature4b. For this reason, it is inevitable for the conventional technology to control the revolving speed of the fan1by estimating the highest temperature status for the devices5a,5b. In this case, it is likely that the fan1will be control at an unnecessarily higher value of revolving speed. In contrast, the present embodiment is designed to estimate the inlet temperature4bbased on the inlet temperature4aand the usage rate of the device5a. This makes it possible to determine the optimum revolving speed of the fan1depending on the temperature status of any device, which prevents a temperature sensor from being attached thereto, based on the inlet temperature4aand the usage rate of the device5aas well as the inlet temperature4band the usage rate of the device5b. Thus, it is possible to operate the fan1at adequate revolving speed enough to cool all the devices installed in the computer equipment. In addition, the present embodiment is able to prevent the fan1to operate at an unnecessary higher value of revolving speed; hence, it is possible to achieve power saving and the reduction of noise due to the operation of the fan1.

As described above, the devices5a,5bare detachably attached to the device module6. Next, the fan control method for the fan1will be described with respect to two scenarios concerning the device5aor5bthat is not attached to the device module6.

(i) First Scenario

In the first scenario that the device5ais not attached to the device module6, the inlet temperature4aindicates the inlet temperature of the device5b. The fan revolving speed determination part132determines the revolving speed of the fan1with reference to the fan control table152bofFIG. 6using the inlet temperature4aand the usage rate of the device5b. In this case, the fan revolving speed determination part132compares the value registered in the item of “inlet temperature (4b)” with the inlet temperature4ameasured by the temperature sensor3with reference to the fan control table152b. The fan revolving speed determination part132determines the fan revolving speed of the fan1suited to cooling of the device5bas the final revolving speed for the fan1.

(ii) Second Scenario

In the second scenario that the device5ais not attached to the device module6, it is possible to adopt the foregoing process that has been described with reference toFIG. 7.

The fan control method of the present invention is not necessarily applied to the computer equipment100ofFIG. 2; hence, it is possible to modify the fan control method adapted to other embodiments of computer equipment shown inFIGS. 8 to 10, wherein the same parts as those shown inFIG. 2are denoted using the same reference signs; hence, detailed descriptions thereof will be omitted as necessary.

2. Second Embodiment

FIG. 8is a block diagram of computer equipment100aimplementing a fan control system according to the second embodiment of the present invention. Similar to the computer equipment100ofFIG. 2, the fan1, the CPU2, the temperature sensor3, and the device module6are aligned along an air flow inside the casing of the computer equipment100a. InFIG. 8, the device module6includes three devices5a,5b,5cthat are aligned in a direction from the upstream to the downstream of an air flow. Arrow symbols A1through A6show an air flow caused by the fan1. In the computer equipment100aofFIG. 8, the fan control apparatus10controls the revolving speed of the fan1such that the temperatures of the devices5a,5b,5cwill fall within an appropriate range of temperature. Three types of temperature estimation tables151athrough151care stored in the storage unit15. Specifically, the outlet temperature (i.e. the inlet temperature4bof the device5b) is registered in the temperature estimation table151ain correspondence with the inlet temperature4aand the usage rate of the device5a; the outlet temperature of the device5b(i.e. an inlet temperature4cof the device5c) is registered in the temperature estimation table151bin correspondence with the inlet temperature4band the usage rate of the device5b; the outlet temperature of the device5c(i.e. an inlet temperature4dof the device5d) is registered in the temperature estimation tale151cin correspondence with the inlet temperature4cand the usage rate of the device5c. In addition, four types of fan control tables152athrough152dare stored in the storage unit15. Specifically, the revolving speed of the fan1is registered in the fan control table151ain correspondence with the inlet temperature4aand the usage rage of the device5a; the revolving speed of the fan1is registered in the fan control tale151bin correspondence with the inlet temperature4band the usage rate of the device5b; the revolving speed of the fan1is registered in the fan control table152cin correspondence with the inlet temperature4cand the usage rate of the device5c; the revolving speed of the fan1is registered in the fan control table152din correspondence with the inlet temperature4dand the usage rate of the device5d.

The processing of the fan control apparatus10adapted to the computer equipment100awill be described with reference to the flowchart ofFIG. 7. First, the temperature estimation part131acquires the inlet temperature4a(step S11). The device usage rate acquisition part12acquires the usage rates of the devices5a,5b,5c, and5d(step12). Next, the temperature estimation part131estimates the inlet temperature4bof the device5bwith reference to the temperature estimation table151ausing the measured inlet temperature4aof the device5a(which is measured by the temperature sensor3and the usage rate of the device5a. Similarly, the temperature estimation part131estimates the inlet temperature4cof the device5cwith reference to the temperature estimation table151busing the estimated inlet temperature4band the usage rate of the device5b. The temperature estimation part131estimates the inlet temperature4dof the device5dwith reference to the temperature estimation table151cusing the estimated inlet temperature4cand the usage rate of the device5c(step S13).

Next, the fan revolving speed determination part132determines the revolving speed of the fan1suited to the temperature status of the device5awith reference to the fan control table152ausing the inlet temperature4aand the usage rate of the device5a. The fan revolving speed determination part132determines the revolving speed of the fan1suited to the temperature status of the device5bwith reference to the fan control table152busing the inlet temperature4band the usage rate of the device5b. The fan revolving speed determination part132determines the revolving speed of the fan1suited to the temperature status of the device5cwith reference to the fan control table152cusing the inlet temperature4cand the usage rate of the device5c. The fan revolving speed determination part132determines the revolving speed of the fan1suited to the temperature status of the device5dwith reference to the fan control table152dusing the inlet temperature4dand the usage rate of the device5d(step S14).

Next, the fan revolving speed determination part132selects the highest value among the revolving speeds of the fan1suited to the temperature statuses of the devices5athrough5d, thus determining the optimum revolving speed of the fan1(step S15).

In the situation that the device module6includes three or more devices5aligned along an air flow, it is possible for the present embodiment to estimate the outlet temperature of each device based on its inlet temperature and usage rate; in other words, it is possible to estimate the inlet temperature for each of the devices aligned from the upstream to the downstream of an air flow by repeating the process of estimating the inlet temperature of a subsequent device adjoining each device in the downstream side of an air flow. In addition, it is possible to estimate the temperature status of each device based on the estimated inlet temperature of each device and its usage rate obtained from the device usage rate management software20. Moreover, it is possible to determine the revolving speed of the fan1able to supply an adequate cooling air depending on the temperature status of each device. Thus, it is possible for the fan control apparatus10to optimally control the fan1in the computer equipment100aofFIG. 8including three or more devices5linearly aligned along an air flow.

FIG. 9is a block diagram of computer equipment100bimplementing a fan control system according to the third embodiment of the present invention. In the computer equipment100bofFIG. 9, the device module6includes three devices5a,5b, and5e. Similar to the device module6shown inFIG. 2, the device module6shown inFIG. 9includes a pair of devices5a,5baligned along an air flow. In addition, the device module6ofFIG. 9further includes the device5ejuxtaposed to the device5b, wherein a pair of devices5b,5eare aligned in a perpendicular direction to the air-flow direction. Moreover, the computer equipment100bofFIG. 9differs from the computer equipment100ofFIG. 2in that the fan1is disposed in the downstream side of an air flow in the casing. Similar to the computer equipment100, the computer equipment100bhas the same positional relationship of the CPU2and the temperature sensor3. In this connection, it is possible to place the fan1at an arbitrary position in the casing of the computer equipment100bas long as the positional relationship between the CPU2and the temperature sensor3can be maintained as shown inFIG. 2. In the computer equipment100b, the fan1blows in air so as to cause the air flow shown by arrow symbols A1through A4.

In the case of the computer equipment100b, the temperature estimation table151a, the fan control table152a, the fan control table152b, and a fan control table152eare stored in the storage unit15of the fan control apparatus10. Specifically, the outlet temperature of the device5a(i.e. the inlet temperature4bof the device5b) is registered in the temperature estimation table151ain correspondence with the inlet temperature4aand the usage rate of the device5a. In addition, the revolving speed of the fan1is registered in the fan control table152ain correspondence with the inlet temperature4aand the usage rate of the device5a; the revolving speed of the fan1is registered in the fan control table152bin correspondence with the inlet temperature4band the usage rate of the device5b; the revolving speed of the fan1is registered in the fan control table152ein correspondence with the inlet temperature and the usage rate of the device5e. In the case of the device module6shown inFIG. 9, it is possible to use the outlet temperature of the device5a(i.e. the inlet temperature4bof the device5b) as the inlet temperature of the device5e.

Next, the processing of the fan control apparatus10adapted to the computer equipment100bwill be described with reference to the flowchart ofFIG. 7. The revolving speed of the fan1depending on the temperature statuses of the devices5a,5bhas been described with reference toFIG. 7. Therefore, the revolving speed of the fan1depending on the temperature status of the device5ewill be described below. Herein, a series of steps S11through S13shown inFIG. 7are similarly applied to the fan revolving speed determination process for the device5e. The fan revolving speed determination part132determines the revolving speed of the fan1depending on the temperature status of the device5ewith reference to the fan control table152eusing the inlet temperature4band the usage rate of the device5e(step S14). Then, the fan revolving speed determination part132selects the highest value among the revolving speeds of the fan1which are determined for the devices5a,5b, and5e, thus determining the optimum revolving speed of the fan1(step S15).

In the device module6that the device5eis juxtaposed to the device5badjoining the device5ain the downstream side, it is possible to determine the revolving speed of the fan1depending on the temperature status of the device5eby using the outlet temperature of the device5aas the inlet temperature of the device5e.

FIG. 10is a block diagram of computer equipment100cimplementing a fan control system according to the fourth embodiment of the present invention. In the computer equipment100c, a device5fis disposed subsequent to the device5ain the downstream side without using the device module6. The first to third embodiments are designed to determine the revolving speed of the fan1by estimating the temperature status of a subsequent device (e.g. the device5b) which is installed in the device module6but is not equipped with its temperature sensor. The fourth embodiment differs from the first to third embodiments such that it estimates the temperature status of the device5fdisposed subsequent to the device5ain the downstream side so as to control the fan1depending on the estimated temperature status.

In the case of the computer equipment100cofFIG. 10, the fan control apparatus10stores the temperature estimation table151a, which registers the outlet temperature of the device5a(i.e. an inlet temperature4fof the device5f) in correspondence with the inlet temperature4aand the usage rate of the device5a, in the storage unit15. In addition, the storage unit15stores a fan control table152fthat registers the revolving speed of the fan1in correspondence with the inlet temperature4fand the usage rate of the device5fin addition to the fan control table152athat registers the revolving speed of the fan1in correspondence with the inlet temperature4aand the usage rate of the device5a.

Next, the processing of the fan control apparatus10adapted to the computer equipment100cwill be described with reference to the flowchart ofFIG. 7. Herein, the fan revolving speed determination process concerning the device5ahas been described with reference toFIG. 7. Therefore, the fan revolving speed determination process concerning the device5fwill be described with reference toFIG. 7. A series of steps S11through S13are similarly applied to the fan revolving speed determination process concerning the device5f. The fan revolving sped determination part132determines the revolving speed of the fan1depending on the temperature status of the device5fwith reference to the fan control table152fusing the inlet temperature4fand the usage rate of the device5f(step S14). Then, the fan revolving speed determination part132selects a higher value between the revolving speeds of the fan1that are determined for the devices5a,5f, thus determining the optimum revolving speed of the fan1(step S15).

As described above, the fan control apparatus10of the present embodiment is able to optimize the revolving speed of the fan1irrespective of whether or not the device5aand its subsequent device are mounted on the device module6such as an add-in card.

The fan control apparatus10implements a computer system, wherein programs implementing the foregoing processes are stored on computer-readable storage media; hence, the computer system reads and executes those programs so as to implement the foregoing processes. Herein, the term “computer-readable storage media” refer to magnetic disks, magneto-optical disks, CD-ROM, DVD-ROM, semiconductor memory, and the like. In addition, it is possible to distribute computer programs to a computer system through communication lines, and therefore the computer system may execute computer programs. The programs may embody part of the foregoing functions. Alternatively, the programs may be differential programs (or differential files) which are combined with pre-installed programs of a computer system so as to implement the foregoing functions.

Moreover, part of or the entirety of the functions of the fan control apparatus10can be realized using hardware components such as ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), and PLC (Programmable Logic Controller).

Lastly, the present invention is not necessarily limited to the foregoing embodiments, which can be further modified by changing or replacing constituent elements within the scope of the invention as defined by the appended claims.