JP5629469B2 - Blower rotational speed detection method and rotational speed detector - Google Patents

Description

  The present invention relates to a rotation speed detection method and a rotation speed detection apparatus for a blower used for cooling an electronic device or the like.

  Conventionally, as a method for detecting the rotational speed of a blower, a method of providing a tachometer, encoder, resolver or other detector inside the blower (Patent Document 1), a method of embedding a magnet at the tip of a blade, and detecting the passage by a sensor (patent) Document 2), a method of detecting the leakage magnetic flux with a loop antenna and detecting the rotation of the blower (Patent Document 3).

JP-A-4-021811 Japanese Utility Model 1-058166 JP 2006-226694 A

However, these conventional methods have the following problems.
In the method of providing a rotation detector inside the blower, a speed detector must be provided when designing and manufacturing the blower, and cannot be added later.
The method of embedding a magnet at the blade tip is also the same, and it is not easy to process the existing blower later.
Furthermore, in the method of detecting leakage flux with a loop antenna, the actual leakage flux signal waveform is distorted instead of the ideal waveform as in principle. It must be factored in and it will be expensive as a whole.

A blower sends out air with a blade | wing, circulates air, or cools a target object. If there is an abnormality in the blower and it stops, there is a risk of serious impact on the equipment and the environment. Therefore, a blower with a rotation abnormality detector is often used in advance for important parts.
However, a rotation abnormality detection function may be required after installing a normal blower.

  An object of the present invention is to solve such a conventional problem and to provide an inexpensive rotational speed detection method and rotational speed detection apparatus that can be easily attached to an existing blower and that are inexpensive.

In order to solve the above problem, the present invention, an opening is provided in the casing wind tunnel side of the blower, the sensor installed in the opening, and detects the pulse frequency of the wind generated by the blower at the sensor, by dividing the pulsation frequency in the number of blades of the blower is to determine the rotational speed of the feed air blower.
In the present invention, the opening is covered with a member that reversibly changes its shape under the pressure of air, a sensor is installed on the member that reversibly changes, and the pulsation frequency of wind generated by the blower Is detected by the sensor .
Furthermore, the present invention consists of a sensor unit for detecting the ripple frequency of the wind generated by the blower, an arithmetic circuit unit by dividing the detected pulsation frequency number of blades of the blower and determines a rotation speed of the blower The sensor portion is provided in an opening portion on a side surface of the casing wind tunnel of the blower .
In the present invention, the sensor unit for detecting the pulsation frequency is provided at an opening on a side surface of the casing wind tunnel of the blower, and a member whose shape is reversibly changed by pressure is provided on the member. It consists of an element that converts a position into an electric signal.
Furthermore, in the present invention, an alarm unit is provided that issues a warning when the rotational speed of the blower is out of a predetermined range .

According to the present invention , since the frequency of the wind generated by the blower is directly detected, the rotational speed of the blower can be obtained with high accuracy.
According to the present invention , since the pulsation frequency of the casing of the blower is detected, it is very easy to detect the frequency.
ADVANTAGE OF THE INVENTION According to this invention , the rotational speed of a fan can be detected with the simple apparatus provided with the sensor and the arithmetic circuit.
According to the present invention , since the rotation speed of the blower is required by installing the sensor near the air intake port or the discharge port of the blower, it is very easy to attach and detach the device.
ADVANTAGE OF THE INVENTION According to this invention , the rotational speed of a fan can be detected with the simple apparatus provided with the sensor and the arithmetic circuit.
According to the present invention , since the pulsation of the wind generated by the blades of the blower is detected by the pressure change on the side surface of the wind tunnel, the rotational speed of the blower can be obtained with high accuracy.
According to the present invention, it is possible to easily detect an abnormality in the rotational speed of the blower.

It is the perspective view which showed the rotational speed detection apparatus of the air blower by one embodiment of this invention, and illustrated the state which opened the sufficiently small hole in the wind tunnel side surface of the air blower, and attached the sensor. It is a detection waveform when a condenser microphone is attached to a seven-blade fan as shown in FIG. It is a perspective view which shows the rotational speed detection apparatus of the air blower by other embodiment of this invention, and shows the state which attached the sensor using the hinge near the air outlet of the air blower. It is the perspective view which showed the rotational speed detection apparatus of the air blower by other embodiment of this invention, provided the opening part which stuck the thin film in the wind tunnel of the air blower, and attached the sensor. FIG. 5 is a side view of FIG. FIG. 5 is a cross-sectional view taken along line AA in FIG. It is the perspective view which showed the rotational speed detection apparatus of the air blower by other embodiment of this invention, and illustrated the casing for fixing a sensor and an arithmetic circuit apparatus to an air blower.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
4 to 6 show a blower 10 used for cooling an electronic device or the like. The blower 10 includes a rotating body 11 that is rotated by a built-in motor (not shown) and a casing 12 that supports the rotating body 11. The rotating body 11 is provided with a plurality of blades 11b radially at regular intervals in the circumferential direction on the peripheral surface of a cylindrical rotating portion 11a. The casing 12 includes a pair of frames 13a and 13b having a substantially circular opening on the inside and a cylindrical wind tunnel portion. The rotating body 11 is supported on the central axis of the wind tunnel portion 14.
The blower 10 is provided with an opening 14a in the cylindrical wind tunnel portion 14 of the casing 12, and a thin film 15 is attached so as to cover the opening 14a. A sensor 16 is affixed to the film 15 so that a change in the position of the film 15 due to the air pressure when the blower 10 is operated is detected by the sensor 16, and air density waves caused by the passage of the blades 11 b are detected. can do.
Instead of the thin film 15, rubber or a thin metal may be used. If the material of the wind tunnel portion 14 is sufficiently thin, the sensor 16 may be directly attached.

  In general, the relationship between the number of blades 11b per unit time passing through a fixed point of the blower 10 and the rotational speed (rotational speed) of the blower 10 is expressed by the following equation.

n = 60 · f / a (1)
n: number of rotations [rpm], f: number of times of passage of blades [times / second], a: number of blades [sheets]

  In the wind tunnel portion 14 of the blower or the air flow path, air dense waves are generated by the passage of the blades 11b, and the frequency thereof is the same as the number of passages f of the blades 11b.

  The density wave is detected by a sensor 16, such as a condenser microphone, a pulsation pickup, an acceleration sensor or a piezoelectric sensor, and the number of passages f of the blade 11b is obtained. If the calculation is performed according to the equation (1), the rotational speed of the blower 10 is calculated. Can be sought.

  FIG. 1 shows another embodiment of the present invention, in which a small hole is formed in the side surface of the wind tunnel portion 14 and a sensor 16 is installed to directly detect the air density wave. The same parts as those in FIG. 4 are denoted by the same reference numerals.

FIG. 2 shows a detection waveform when a condenser microphone is attached to a seven-blade fan as shown in FIG.
In this example, since the frequency is about 322 Hz, the rotation speed is about 2765 rpm as calculated by Equation (1).

  In the air in the vicinity of the air intake port 17a and the air outlet port 17b of the wind tunnel portion 14, air density waves are generated. There is a method in which an acceleration sensor, an angle sensor, or the like is installed and detected via a material that is deformed in a moving manner.

  FIG. 3 is a conceptual diagram in which the pulsation sensor 16 is fixed to the air outlet 17b with a hinge 18. The hinge 18 is obtained by attaching a small piece 19a around the pin portion 19 to the wind tunnel portion 14 and the like, and attaching the sensor 16 to the other small piece 19b. The position of the small piece 19b reversibly changes around the pin portion 19 due to wind pulsation. The position of the small piece 19b is converted into an electric signal by the sensor 16.

  FIG. 7 is a diagram illustrating a state in which the rotation speed detector 20 in which the sensor unit and the arithmetic circuit unit are housed in one housing is fixed to the blower casing wind tunnel unit 14.

  In addition, there exists a method of calculating with a microcomputer as a method of calculating | requiring the rotation speed of an air blower based on the detected frequency or period. According to the microcomputer, it is easy to issue a warning when the speed falls below or exceeds a predetermined speed.

  There is also a method of issuing a warning by comparing a predetermined time with a detected cycle using a timer or the like.

  If these circuit devices are attached to the blower, it is possible to provide a blower with a rotation abnormality alarm that is easy to handle.

  In addition, this invention is not limited only to the said embodiment, For example, as an air blower, it can apply to various air blowers, such as an axial fan, a sirocco fan, and a cross flow fan. In addition, various sensors such as an acceleration sensor, an angle sensor, and a piezoelectric element can be applied to detect pulsation. Needless to say, the present invention can be implemented with appropriate modifications without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Blower 11 Rotating body 11a Rotating part 11b Blade 12 Casing 14 Wind tunnel 15 Thin film 16 Sensor 17a Air intake 17b Air outlet 18 Hinge 20 Rotation speed detector

Claims (5)

Provide an opening on the side of the casing wind tunnel of the blower,
Install a sensor in the opening,
The pulse frequency of the wind generated by the blower is detected by the sensor,
By dividing the pulsation frequency by the number of blades of the blower,
Rotational speed detection method of the blower, characterized in that determining the rotation speed of the feed air blower. Covering the opening with a member whose shape changes reversibly under the pressure of air,
A sensor is installed on the reversibly changing member,
The pulsation frequency of the wind generated by the blower is detected by the sensor.
The method of detecting the rotational speed of the blower according to claim 1. A sensor unit for detecting the pulsation frequency of the wind generated by the blower;
The detected pulse frequency by dividing the number of blades of the blower consists of a computing circuit section for obtaining the rotation speed of the blower,
The rotation speed detection device for a blower , wherein the sensor unit is provided in an opening on a side surface of a casing wind tunnel of the blower. The sensor unit for detecting the pulsation frequency is provided in an opening on a side surface of the casing wind tunnel of the blower, and a member whose shape is reversibly changed by pressure and a position provided on the member are converted into an electric signal. The device for detecting a rotational speed of a blower according to claim 3 , comprising: Rotational speed of the blower, rotation speed detecting apparatus of the blower of claim 3 or 4, characterized by comprising an alarm unit for issuing an alarm when deviated from a predetermined range.

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