JP2001248588A - Rotational speed controlling system for cooling fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems is a conventional cooling fan arranged in a personal computer and the like which gives us unpleasant noise due to cooling fan working sound or its wind noise in same case and deteriorates a peripheral atmosphere by continuously turning at a maximum rotational speed during its operation. SOLUTION: This rotational speed controlling system for a cooling fan is provided with a means storing a rotational speed of the cooling fan 1 as a maximum rotational speed cM measured when a motor 1a is driven at a maximum capacity and driving the motor 1a so that the rotation speed c of the cooling fan 1 makes a necessary ratio to the maximum rotational speed cM.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling the rotation speed of a cooling fan provided for forcibly discharging heat generated in electric equipment and the like.

[0002]

2. Description of the Related Art In recent years, information processing devices such as personal computers and so-called digital home appliances incorporating them have begun to spread widely. In such devices, power consumption tends to increase due to higher performance and the like, and accordingly, the amount of heat generated by components and the like constituting the devices has also increased. In addition, cases where heat generation is concentrated due to miniaturization of devices are increasing.

[0003] Therefore, in order to protect the equipment itself and the user from such heat, the capacity of the forced heat removal device provided inside the equipment is increased, or the equipment which could be conventionally used with natural heat radiation can be used. Also, the necessity of newly installing a forced heat removal device is increasing. The forced heat removal device generally has a cooling fan, and by rotating the cooling fan, a wind is applied to a radiator plate or the like to promote heat exchange, or the inside of the device is ventilated to reduce the temperature of the device. Lower it.

[0004]

Many conventional cooling fans simply turn on / off in conjunction with the main power supply of the equipment. Therefore, the device constantly rotates at the maximum rotation speed while the device is operating. However, as these devices become more sophisticated and smaller, and are used in various places and situations, the operating noise and wind noise of the cooling fans provided in those devices may be unpleasant. In some cases, it has become a problem or the surrounding atmosphere has been damaged.

[0005] In order to solve the above-mentioned problems, the cooling capacity of the cooling fan, that is, the rotation speed of the cooling fan may be controlled so as to be a necessary minimum according to the temperature of the equipment. With such a configuration, unnecessary rotation of the cooling fan can be prevented, so that noise such as operation noise and wind noise can be reduced. In addition, it can contribute to a reduction in power consumption. Various techniques have been proposed for such a cooling fan rotation speed control system. Here, a description will be given of the conventional technology and the problems that each conventional technology has.

First, in the conventional configuration in which the cooling fan is turned on only when the temperature of the device reaches a temperature that requires forced cooling, the cooling fan is turned off if the temperature of the device is lower than a predetermined value. Power consumption and noise. However, since the control of the cooling fan is still only on / off, the cooling fan is set to the maximum rotation speed from the moment when the temperature of the device reaches a predetermined value, that is, when the forced cooling is required but a small amount of cooling is sufficient. Therefore, there is still a problem in terms of power consumption and noise.

Next, in the conventional configuration in which the rotation speed of the cooling fan is changed in accordance with the temperature of the device by variable voltage driving, intermittent driving, or the like, the cooling fan is rotated at an optimum rotation speed according to the situation, in other words, the minimum required speed. The rotation speed can be controlled. This makes it possible to minimize power consumption and noise.

However, the rotation starting voltage at which the cooling fan starts rotating in the variable voltage driving has a difference between models of the cooling fan and a variation between individuals. Also, the voltage-rotational speed characteristic during the change of the magnitude of the control voltage applied to the cooling fan from the rotation starting voltage to the maximum drive voltage is not always linear, and such characteristics change with aging. Therefore, in the open-loop control in which an intermediate voltage is set in advance between the rotation starting voltage and the maximum driving voltage and the cooling fan is driven at a desired rotation speed by applying the intermediate voltage, the cooling described above is performed. It is difficult to design in consideration of variations and aging of the fan.

When the rotation speed of the cooling fan is controlled by intermittent driving, the duty ratio at which the rotation of the cooling fan starts varies between models and varies, and the duty ratio-rotation speed characteristic is linear. Not necessarily. Therefore, as in the case of the above-described variable voltage driving, there is a problem that it is difficult to design in consideration of variation and aging of the cooling fan.

On the other hand, a general closed-loop control rotational speed servo used for a CD player, a video deck, etc.
In order to accurately sample an audio signal, a video signal, or the like from a D, a video tape, or the like, it is used for the purpose of strictly adjusting the absolute rotation speed to a target rotation speed according to a standard. Therefore, when such a rotation speed servo is applied to the rotation speed control system of the cooling fan as it is,
Precise reference clock for determining the rotation speed of the cooling fan, filtering of oscillation prevention, matching of filters for differences between models / individual variations of the cooling fan, setting of target rotation speed, etc. are required, which is complicated and expensive. System.

In view of the above problems, the present invention provides a cooling fan rotation speed control system capable of controlling the rotation speed of a cooling fan to an optimum rotation speed in accordance with the temperature of equipment and the like with a simple configuration. The purpose is to:

[0012]

To achieve the above object, a cooling fan rotation speed control system according to the present invention comprises a cooling fan, a motor for rotating the cooling fan, and a rotation speed of the cooling fan. Means for measuring the rotation speed of the cooling fan measured when the motor is driven at the maximum capacity, the rotation speed of the cooling fan as the maximum rotation speed of the cooling fan, the rotation speed of the cooling fan to the maximum rotation speed And a means for driving the motor so that the required rotational speed is at a required rate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of a configuration of a cooling fan rotation speed control system according to the present invention. As shown in the figure, the cooling fan rotation speed control system according to the present invention includes a cooling fan 1 and a motor 1.
a, a rotation clock generation unit 1b, a reference clock generation unit 2, a rotation speed measurement unit 3, a maximum rotation speed storage unit 4, a target rate acquisition unit 5, a target rotation speed calculation unit 6, a motor drive unit 7 are provided.

Here, an example in which the rotation speed of the cooling fan 1 is controlled by a variable voltage drive will be described. However, the rotation speed control system according to the present invention is not limited to this, and other drive control means may be used. (Intermittent driving, etc.).

The motor 1a is for rotating the cooling fan 1 and has a control voltage f applied from the motor driving means 7.
It rotates at a rotation speed according to the size of. The rotation clock generating means 1 b generates a rotation clock signal a synchronized with the rotation of the cooling fan 1 and outputs the rotation clock signal a to the rotation speed measurement means 3. The reference clock creating means 2 creates a reference clock signal b serving as a reference time for measuring the rotation speed of the cooling fan 1, and outputs the reference clock signal b to the rotation speed measurement means 3. The reference clock generator 2 is composed of a CR oscillation circuit and the like.

The rotational speed measuring means 3 has, for example, a counter 3b for measuring the number of pulses of the reference clock signal b, and a capture controller 3a for starting / stopping the operation of the counter 3b at the rise of the rotational clock signal a. By measuring how many pulses of the reference clock signal b are input during one clock of the rotation clock signal a, the rotation speed c of the cooling fan 1 (the relative speed of the rotation clock signal a to the reference clock signal b) is measured. Is what you do.

Here, the rotation speed control system according to the present invention applies a maximum control voltage f to the motor 1a once when the cooling fan 1 starts to rotate, so that the motor 1a is driven at the maximum capacity. Is stored in the maximum rotation speed storage means 4 as the rotation speed of the cooling fan 1 measured as the maximum rotation speed c _M. Maximum rotation speed storage means 4
Is the maximum rotation speed c _M input from the rotation speed measurement means 3
And outputs the maximum rotation speed c _M to the target rotation speed calculation means 6.

The value of the maximum rotation speed c _M stored in the maximum rotation speed storage means 4 may be updated each time the maximum control voltage f is applied to the motor 1a, or the maximum value measured at that time may be updated. The update may be performed only when the value of the rotation speed c _M is larger than the value currently stored. If the maximum rotation speed c _M is configured to be stored and updated in this manner, the maximum rotation speed c _M may be reduced due to dust or the like adhering to the cooling fan 1, or conversely, due to an increase in the temperature of the device. Even when the oscillation frequency of the reference clock signal b decreases and the maximum rotation speed c _M relatively increases, the accurate maximum rotation speed c _M can always be recognized.

The target rate obtaining means 5 receives a target rate d input from the outside, and outputs the target rate d to the target rotation speed calculating means 6. The target rate d is a value indicating the ratio of the target rotation speed e to the maximum rotation speed c _M of the cooling fan 1. For example, when setting the target rotation speed e to half of the maximum rotation speed c _M , “50
% "Is input to the target rate obtaining means 5.

If the target rate d is received from a system controller or the like that monitors the temperature of the equipment, the rotation speed c of the cooling fan 1 can be controlled to an optimum value according to the temperature of the equipment. . On the other hand, in the so-called power saving mode in which the reduction of power consumption is the highest priority, the target rate d is intentionally set regardless of the temperature of the device in order to prioritize the reduction of power consumption over the cooling capacity of the cooling fan 1. It is also conceivable to adopt a configuration in which it is lowered.

The target rotational speed calculating means 6 calculates the maximum rotational speed c.
_{Based on M} and the target rate d, a target rotation speed e for performing servo control on the motor 1 a is calculated, and the target rotation speed e is output to the motor driving means 7. Motor driving means 7
Is a control to compare the rotation speed c of the cooling fan 1 input from the rotation speed measurement means 3 with the target rotation speed e input from the target rotation speed calculation means 6 and to apply them to the motor 1a so that they match. The magnitude of the voltage f is updated. That is, if the rotation speed c of the cooling fan 1 is smaller than the target rotation speed e, the rotation speed c is increased in the direction in which the motor 1a is accelerated.
Is larger than the target rotation speed e, the magnitude of the control voltage f may be changed in a direction to decelerate the motor 1a.

Here, depending on how much the control voltage f applied to the motor 1a is changed by one feedback loop, the rotation speed c may not oscillate to the target rotation speed e and may oscillate. In order to prevent such oscillation, the convergence allowable range of the rotation speed c with respect to the target rotation speed e, that is, the range in which it is determined that the rotation speed c matches the target rotation speed e may be set to be relatively large.
In the rotation speed control system of the cooling fan 1, since it is not necessary to perform strict rotation speed control as compared with the rotation speed servo used for a CD player or the like, the convergence allowable range of the rotation speed c may be set relatively large.

Further, the amount of change of the control voltage f / 1 loop is set to be sufficiently small, and the rotation speed c of the cooling fan 1 gradually decreases.
May be controlled. By performing such control, the rotation speed c of the cooling fan 1 gradually approaches the target rotation speed e, so that there is little possibility of oscillation, and no more advanced filtering is required.

On the other hand, as a means for measuring the rotation speed of the cooling fan 1, a configuration shown in FIG. FIG. 2 shows another configuration example of the means for measuring the rotation speed of the cooling fan 1. The rotation speed measuring means 3 'is provided with a prescaler 3c in addition to the capture controller 3a and the counter 3b. here,
The set values of the counter 3b and the prescaler 3c have the same resolution (here, 5 bits), and the prescaler 3c sets the oscillation frequency of the reference clock signal b to a fraction of an integer (the fraction of the set value). ) And the clock signal b '
Is output to the counter 3b.

The operation of the rotation speed measuring means 3 'is basically the same as that of the above-described rotation speed measuring means 3, except that the clock signal b' inputted during one clock of the rotation clock signal a.
Is counted, and the pulse number c is used as the rotation speed c of the cooling fan 1. The difference between the rotation number measuring means 3 'and the above-described structure is that when the cooling fan 1 is rotated at the maximum capacity, the set value of the prescaler 3c is set to the initial value 16 (intermediate value of 5 bits) and the clock signal b' is set. Is counted, and the pulse number c at that time is counted.
That is, the set value of the prescaler 3c is changed according to the maximum rotation speed.

The operation of the rotation speed measuring means 3 'will be described with reference to FIG. FIG. 3 is a timing chart showing the operation of the rotation speed measuring means 3 '. In FIG. 3A, the number of pulses c of the clock signal b ′ counted by the counter 3b is 10 during one clock of the rotation clock signal a input when the cooling fan 1 is rotated at the maximum capacity. Shows the case. In this case, since the prescaler 3c stores "10" as a new set value, the number of pulses counted by the counter 3b becomes 16 when the cooling fan 1 is subsequently rotated at the maximum capacity.

On the other hand, FIG. 2B shows that the maximum rotation speed of the cooling fan 1 decreases for some reason and the rotation clock signal a
In this case, the number of pulses c of the clock signal b ′ counted by the counter 3b is 13 during one clock. Even in this case, the prescaler 3c sets “1”.
Since "3" is stored as a new set value, the number of pulses counted by the counter 3b becomes 16 when the cooling fan 1 is subsequently rotated at the maximum capacity. With this configuration, when the cooling fan 1 is rotated at the maximum capacity, the pulse number c of the clock signal b ′ counted by the counter 3b, that is, the maximum rotation speed of the cooling fan 1 is always 1
6 can be set.

Therefore, for example, if the target rotational speed of the cooling fan 1 is to be set to 50% of the maximum rotational speed, the counter 3
motor 1a until the number of pulses c measured in b reaches 32
If the cooling fan 1 is to be rotated at a rate of 80%, the magnitude of the control voltage f is changed so that the pulse number c becomes 20. Let me do it.

That is, in the above configuration, the rotation speed c of the cooling fan 1 is simply compared with the rotation speed c obtained from the rotation speed measuring means 3 'and a predetermined count number (for example, 20/24/32 counts). Can be controlled, the target rotation speed calculating means 6 is not required. In addition, cooling fan 1
The operation of changing the set value of the prescaler 3c when rotating the prescaler 3c at the maximum capacity is indirectly performed by the prescaler 3c.
Since the maximum rotation speed is stored in c, there is no need to separately provide the maximum rotation speed storage means 4 described above. Therefore, a rotation speed control system for the cooling fan 1 can be realized with a simpler configuration.

FIG. 3 shows a case where the pulse number c of the clock signal b 'is ideally counted in the counter 3b. However, in actuality, the case where the cooling fan 1 is rotated at the maximum capacity due to a sampling error. The pulse number c of the clock signal b 'counted by the counter 3b
May not be 16. Although such sampling error components can be relatively reduced by increasing the resolution of the counter 3b and the prescaler 3c,
It cannot be completely eliminated. Therefore, when designing the rotation speed control system, it is desirable to select an appropriate resolution according to the required performance and to perform the design in consideration of such an error component.

As described above, the cooling fan rotation speed control system according to the present invention sets the absolute rotation speed of the cooling fan 1 such as a conventional rotation speed servo used for a CD player or the like to a predetermined target. Instead of adjusting the rotation speed (fixed value), the servo control is performed so that the rotation speed of the cooling fan 1 becomes a necessary ratio to the maximum rotation speed. Therefore, the rotation speed of the cooling fan 1 can be optimally adjusted according to the device temperature and the like with a simple configuration without requiring a complicated and expensive system such as an accurate reference clock generating means for determining the rotation speed of the cooling fan 1. It is possible to control the speed.

Although the above description has been given of an example of a configuration for realizing the cooling fan rotation speed control system according to the present invention by hardware means, the rotation speed having the above-mentioned effect can be obtained by software processing by a microcomputer or the like. A control system can be realized.

[0033]

In the cooling fan rotation speed control system according to the present invention, the cooling fan, a motor for rotating the cooling fan, a means for measuring the rotation speed of the cooling fan, and the motor having the maximum capacity. Means for storing the rotation speed of the cooling fan measured at the time of driving as the maximum rotation speed of the cooling fan, and the rotation speed of the cooling fan is a rotation speed of a necessary ratio to the maximum rotation speed. And means for driving the motor.

With such a configuration, like a conventional rotational speed servo used for a CD player or the like,
It is possible to control the cooling fan to the optimum rotation speed according to the equipment temperature etc. with a simple configuration without the need for complicated and expensive systems such as accurate reference clock generation means for determining the rotation speed of the cooling fan Becomes

In particular, the value of the time system used for this closed loop control (rotation speed measured based on the reference clock signal, maximum rotation speed, and target rotation speed based on the maximum rotation speed)
Are all evaluated as relative values, and the target rotation speed of the cooling fan changes according to the maximum rotation speed of the cooling fan at that time. Therefore, even if it includes unspecified factors such as differences between cooling fan models, variations between individuals, aging, variations in voltage-rotational speed characteristics, and variations in oscillation frequency in the reference clock signal, the cooling fan at that time is always present. Can be derived, and relative rotation speed control is possible based on the maximum rotation speed.

Further, in the cooling fan rotation speed control system according to the present invention, the above-described variation of each element can be appropriately tolerated, so that an inexpensive component configuration can be selected, the degree of freedom of circuit, the margin, and the number of components can be reduced. Changes can be made easily.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one configuration example of a cooling fan rotation speed control system according to the present invention.

FIG. 2 is another configuration example of a means for measuring the rotation speed of the cooling fan 1;

FIG. 3 is a timing chart showing an operation of a rotation speed measuring unit 3 ′.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cooling fan 1a Motor 1b Rotation clock creation means 2 Reference clock creation means 3 Rotation speed measurement means 3a Capture controller 3b Counter 3c Prescaler 4 Maximum rotation speed storage means 5 Target rate acquisition means 6 Target rotation speed calculation means 7 Motor drive means

Claims (1)

[Claims] 1. A cooling fan, a motor for rotating the cooling fan, means for measuring a rotation speed of the cooling fan, and a rotation speed of the cooling fan measured when the motor is driven at a maximum capacity. Means for storing as a maximum rotation speed of the cooling fan, and means for driving the motor such that the rotation speed of the cooling fan is a rotation speed of a necessary ratio to the maximum rotation speed. Cooling fan rotation speed control system.