JP2575902B2 - Housing cooling structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a casing cooling structure. 2. Description of the Related Art In recent years, densification of electronic devices has progressed, and accordingly, the amount of heat generated per unit volume has also increased. As a cooling device that is less expensive and has less failures, air blowing by a cooling fan is optimal. However, the cooling fan generates noise due to turbulence in the air flow on the suction side, air resistance of the device, and vibration transmission. There is a need to develop a method for reducing such noise.

2. Description of the Related Art FIG. 5 shows a conventional cooling fan device, in which a housing 1 of an electronic device is provided with a shelf, and a number of electronic circuit boards 2 are mounted side by side on the shelf. An intake duct 3 is provided at a rear end side of the arranged boards 2, and a cooling fan 4 for exhaust is disposed at a rear end of the intake duct 3.
An exhaust duct 5 is provided downstream of the cooling fan 4, and the exhaust duct 5 has a diameter larger than the diameter of the cooling fan 4. A sound absorbing material 6 is fixed to the inner surface of the exhaust duct 5.
The exhaust gas flows on the surface of the sound absorbing material. When the cooling fan 4 rotates, air flows from one side of the housing 1 as shown by an arrow A, receives heat from the board 2 of the electronic circuit, gathers in the intake duct 3, passes through the cooling fan 4, and exits from the exhaust duct 5. Is discharged to Noise generated by turbulence of the air flow on the suction side, air resistance of the device, vibration transmission, etc., passes through the exhaust duct 5, but at this time, the noise is absorbed by the sound absorbing material 6.

[Problems to be solved by the invention]

However, in the conventional device, since the noise generated after the noise is absorbed by the sound absorbing material 6 in the exhaust duct 5, the noise reduction effect is small for the cost, and the noise cannot be significantly reduced. Further, there is a problem that increasing the noise reduction effect also increases the pressure loss. SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described drawbacks, and has as its object to provide a cooling structure of a housing that reduces noise generated by a cooling fan of an electronic device as much as possible.

[Means for Solving the Problems]

The present invention will be described with reference to FIG. 1. A rectifier 10 is disposed on the suction side of the blower fan 4 and in the vicinity thereof.

[Action]

Due to the rotation of the cooling fan 4, air passes through the rectifier 10 and then flows into the cooling fan 4 and is discharged. If the fluid flowing into the flow straightener 10 has turbulence, vortex and uneven flow velocity,
The flow speed is made uniform by 10, and a uniform flow is drawn into the cooling fan 4. And it is discharged outside. Noise is the vibration of the air. The causes are turbulence, vortex, and non-uniform flow velocity, and the flow is rectified to a uniform flow velocity by the flow rectifier 10, so that noise is reduced. Since the pressure is not in the speed range where pressure loss occurs due to the resistance of the rectifier 10, noise reduction can be realized without impairing the blowing capacity.

【Example】

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The housing 1 is provided with a shelf, and the boards 2 of electronic circuits are arranged and mounted on the shelf. A hollow intake duct 3 is provided at the rear end side of the lined boards 2, and a rectifier 10 is desirably provided in the intake duct 3 at a position at least 20 mm or more away from a cooling fan 4 described later. It is arranged. The rectifier 10 rectifies the flow of the fluid, and the shape of the equal cross section may be various shapes such as a polygon, a circle, and an ellipse. Filter) can be considered first. These many fine through holes serve as air ventilation holes. The rectifier 10 is stretched over the entire cross section of the intake duct 3, and a space in the intake duct 3 is divided into a space on the upstream side (front end 11) of the cooling air and a space on the downstream side (rear end 12). ) And can be ventilated. At the center of the rear end of the intake duct 3, a cooling fan 4 for exhaust
The exhaust duct 5 is disposed downstream of the cooling fan 4. The exhaust duct 5 has a diameter larger than the diameter of the cooling fan 4, and a sound absorbing material 6 is fixed to an inner surface thereof. 2 and 3 show a specific example of a filter which becomes the straightening body 10, and FIG. 2 shows a plan view of a wire mesh 16 composed of vertical lines 14 and horizontal lines 15. FIG. That is, in the plain-woven wire mesh 16, adjacent lines are parallel to each other, and vertical and horizontal lines are substantially orthogonal. And the defined eyes 17 are rectangular or square. FIG. 3 shows a plan view of a hexagonal honeycomb structure 18,
As the internal unit hexagon 19, one having a shorter side or one having a larger side can be used. In addition, the size of the mesh 17 of the wire mesh 16 is also set freely according to the wind speed and the air volume. Furthermore, the weave of the wire mesh 16 is not limited to plain weave,
Twill, cedar twill, tatami weaves may also be used. Now, when the cooling fan 4 is rotated, wind flows in the direction of arrow A in FIG.
And is sucked into the cooling fan 4. Thereafter, the wind passes through the exhaust duct 5 and is discharged out of the housing 1. The wind that hits the irregularly mounted components on the board 2 forms a vortex or an uneven flow layer.
Precisely, when flowing into the front end portion 11 of the intake duct 3, as is well known, the wind speed of the cooling air decreases due to the rapid expansion of the cross section of the air passage, and some vortices or uneven flow layers are eliminated. (Preliminary rectification) When reaching the rectifier 10 and passing through the rectifier 10, large vortices and non-uniform flow layers that are not rectified at the front end 11 are finely cut off microscopically, resulting in minute vortices and minute vortices. A non-uniform flow layer results. Since this flow is a uniform flow layer without vortices when viewed macroscopically, the audible noise of air vibration is largely eliminated. Further, noise is further absorbed by the sound absorbing material 6 in the exhaust duct 5. The plain woven wire mesh may be used in a mesh shape with variously changed eye shapes. FIG. 4 shows the measurement results. Graph Y represents the noise level of the conventional device. Conventionally, the noise level is dB (decibel) on the vertical axis and the time T is measured on the horizontal axis using a noise meter, and in the related art, the noise level is high and the noise level changes periodically. Graph X shows the noise intensity when the cooling fan device of the present invention is used. 3dB level noise reduction effect and sound stabilization appear. In accordance with the rotation of the cooling fan, the straightening body is changed to a honeycomb structure with the wire mesh, casing and blade shape, air volume, wind speed characteristics, etc. Vessel can be selected.

【The invention's effect】

As described above, according to the present invention, since the rectifier is disposed on the intake side of the cooling fan that forcibly exhausts the warm air in the housing, the uneven flow velocity that causes noise is made uniform. As a result, air having a uniform flow velocity is sucked into the cooling fan, so that the impact force is suppressed, the sound is stabilized, and the noise level is significantly reduced. Thus, the noise reduction effect can be obtained with a simple structure and at low cost without impairing the air flow capacity of the cooling fan. Further, when the rectifier is arranged at a distance of 20 mm or more from the cooling fan, the noise reduction effect can be further improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of the present invention, FIG. 2 is a plan view of a wire mesh of a filter, FIG. 3 is a plan view of a honeycomb structure of the filter, and FIG. FIG. 5 is a conventional sectional view. In the figure, 1 is a housing, 2 is a board, 3 is an intake duct, 4 is a cooling fan, 5 is an exhaust duct, 6 is a sound absorbing material, 10 is a rectifier, 16 is a wire mesh, and 18 is a honeycomb structure.

Claims (5)

(57) [Claims] 1. A cooling structure for a housing for forcibly exhausting warm air in the housing to an outside of the housing by a blower fan, wherein an intake duct is provided on a suction side of the blower fan, and an intermediate portion between the intake ducts. A rectifier that divides the intake duct into a front end and a rear end so as to allow ventilation is provided in the section. After the turbulence component of warm air generated by passing through the housing is A cooling structure for the casing that rectifies noise by means of a rectifier to reduce noise. 2. The cooling structure for a casing according to claim 1, wherein said rectifier is a filter. 3. A cooling structure for a housing, wherein the filter is a wire mesh. 4. A cooling structure for a casing according to claim 2, wherein said filter is a honeycomb structure having a cross section. 5. An apparatus according to claim 1, wherein an interval between said flow regulating body and said blower fan is at least 20 mm.
A cooling structure for a housing according to any one of the above.