JPH10322071A - Shield plate with projection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield plate with projection which can be improved in cooling efficiency by arranging a plurality of projections having prescribed heights and cross-sectional shapes at optimum intervals. SOLUTION: A shield plate 11 with projection is constituted by arranging three or more projections 120 , 121 , and 122 having square cross sections and heights Hn (H0 , H1 , and H2 ) at the intervals Sn (S1 and S2 ) found from the following expression: 5×(1+K)Hn-1 ÷2<=Sn <=13×(1+K)Hn-1 ÷2 where, H0 =H and K represents the height degreasing rate of the projections, in a direction which is nearly perpendicular to the flowing direction of an air flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielding plate with a projection provided for preventing a temperature rise in a main body of an electric device such as an image forming apparatus.

[0002]

2. Description of the Related Art A conventional technique will be described below with reference to the accompanying drawings.

FIG. 14 is a longitudinal sectional view of an image forming apparatus.
A photosensitive drum 1, which is an image carrier that is driven to rotate in a direction indicated by an arrow in the figure, is disposed substantially at the upper center in the main body 10 of the image forming apparatus.
The cleaner 3, the transfer drum 4, and the developing device 5 are provided respectively. Further, a laser scanner 6 is disposed above the photosensitive drum 1 in the apparatus main body 10, and a cassette 7 in which a plurality of transfer materials P are stacked and accommodated is installed at the bottom in the apparatus main body 10.

Further, a paper feed roller 8 and a fixing device 9 are disposed above the cassette 7 in the apparatus main body 10, and a shielding plate 15 is provided above the fixing device 9 which is a heat generating source. I have. The fixing device 9 includes a fixing roller 9a having a built-in heater (not shown) and a pressure roller 9b which is driven to rotate in contact with the fixing roller 9a.

The photosensitive drum 1 is driven to rotate at a predetermined speed in the direction of the arrow shown in the figure, and is uniformly charged by the primary charging 2. An electrostatic latent image is formed on the image.
Then, the electrostatic latent image is developed by the developing device 5 and visualized as a toner image.

On the other hand, the transfer material P is supplied one by one from the cassette 7 by the paper feed roller 8, and the transfer material P is attracted to the transfer drum 4 and rotates together with the transfer drum 4 in the direction of the arrow shown in FIG. In the process, the toner image formed on the photosensitive drum 1 is transferred.

The transfer material P to which the toner image has been transferred is
Is separated from the transfer drum 4 and sent to the fixing device 9 to fix the toner image by heat and pressure, and is discharged onto a discharge tray 10a outside the apparatus main body 10 through a path indicated by an arrow in the figure. You. The toner remaining on the photosensitive drum 1 is cleaned by a cleaner 3 such as a fur brush or a blade.

[0008]

A shield plate provided around a heat source in an electric device such as an image forming apparatus as described above and a row of projections provided on the shield plate has been conventionally proposed. No projection interval is set for each projection shape in consideration.

Further, even in the case of a shielding plate having projections, the shape, spacing and height of the projections are taken into consideration in consideration of cooling efficiency. It was not what was set.

The present invention has been made in view of the above circumstances, and an object thereof is to improve cooling efficiency by arranging a plurality of projections having a predetermined height and a cross-sectional shape at optimal intervals. It is to provide a shielding plate with a projection.

[0011]

In order to achieve the above object, the present invention according to claim 1 has a height H having a square cross section.
interval is determined at substantially right angles to the formula 3 or more projections of _n with respect to the flow direction of the air _{S n: 5 × (1 +} K) H n-1 ÷ 2 ≦ S n ≦ 13 × (1 + K) H
_n−1 ÷ 2, where H ₀ = H, K: protrusion height reduction coefficient, and a shielding plate with protrusions is configured.

[0012] According to a second aspect of the invention, a semi-elliptical interval determined at substantially right angles to the formula three height H _n more projections with respect to the flow direction of air having a cross-section S _n: 6 × (1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 10 × (1 + K) H
_n−1 ÷ 2, where H ₀ = H, K: protrusion height reduction coefficient, and a shielding plate with protrusions is configured.

[0013] The invention of claim 3, wherein the spacing obtained at substantially right angles to the formula 3 or more high protrusions H _n having a semi-circular cross-section relative to the flow direction of the air S _n: 5 × ( 1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 11 × (1 + K) H
_n−1 ÷ 2, where H ₀ = H, K: protrusion height reduction coefficient, and a shielding plate with protrusions is configured.

[0014] The invention of claim 4, wherein the distance is determined at a substantially right angle equation three or more projections of height H _n having a triangular cross-section with respect to the flow direction of the air _{S n: 5 × (1 +} K ) H _n-1 ÷ 2 ≦ S _n ≦ 13 × (1 + K) H
_n−1 ÷ 2, where H ₀ = H, K: protrusion height reduction coefficient, and a shielding plate with protrusions is configured.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a longitudinal sectional view of an image forming apparatus, FIG. 2 is an enlarged sectional view around a shielding plate with a projection according to the present invention in the image forming apparatus, and FIGS. FIG. 4C is a diagram showing the wind direction of the fan, and FIG. 4 is a perspective view of a shielding plate with projections. The image forming apparatus shown in FIG. 1 has the same configuration as that of the conventional image forming apparatus shown in FIG. 14 except for a protruding shielding plate provided inside the image forming apparatus.
In FIG. 1, the same elements as those shown in FIG. 14 are denoted by the same reference numerals, and description thereof will be omitted below.

As shown in FIG. 1, a shielding plate 11 with a projection according to the present invention is provided between a developing device 5 and a fixing device 9 as a heat source in the image forming apparatus main body.

As shown in FIG. 2, the shielding plate with projections 11 includes a plurality of (three in the illustrated example) projections 12 ₀ , 12.
_1, 12 ₂ is a which are arranged at appropriate intervals S _1, S _2, wherein, the projections 12 _0, 12 _1, 12 attached laterally to the _second shielding plate 11 in FIGS. 2 and 4 It will be described based on the following.

The shielding plate 11 has a square cross section of a side length H _n (H ₀ , H ₁ , H ₂ (n = ₀ , ₁ , 2) in the present embodiment) and a width T _L. 2D square pillar projection 12
₀ , 12 ₁ , and 12 ₂ at intervals S _n (in the present embodiment, S _n
1 , S ₂ (n = 1, 2)) so as to be perpendicular to the air flow. This is the protrusion 12
_{If 0} , 12 ₁ , and 12 ₂ are arranged in parallel to the flow of air, it is difficult for the flow near the wall to mix, and the cooling efficiency is poor. Here, S ₁ and S ₂ are protrusions 12.
₀ , 12 ₁ , and 12 ₂ are the center-to-center distances.

As shown in FIG. 2, a fan 13 is installed in the vicinity of the shielding plate 11, and the louver 13a of the fan 13 swings up and down, as shown in FIG.
The wind direction changes as shown in (a) → (b) → (c).

Next, the projections 12 _0, 12 _1, 12 ₂ of the length T _L the length L _e of the nubbed shielding plate 11 will be described.

The length T _{L of the} projections 12 ₀ , 12 ₁ , 12 ₂
Is the length L _{e of the} shielding plate 11 as much as possible from the viewpoint of increasing the surface area of the shielding plate 11 with projections and increasing the cooling efficiency.
It is desirable to approach.

Next, a description will be given protrusion 12 _0, 12 _1, 12 ₂ height _{H n (H 0, H 1} , H 2) Determination of.

The height H _{0 of} the projections 12 ₀ , 12 ₁ , 12 ₂
H _1, H ₂ is determined from the projection interval S _n to be described later and the height H ₀ of the top corners of the protrusions _{12 0 (S 1, S 2} ). Here, we describe how to determine the height H ₀ of the top corners of the protrusions 12 _0.

[0025] Since air is the ratio of the sectional area of the protrusions 12 ₀ greater the projections 12 ₀ and resistance to Kazerodan area is known to not flow smoothly, the projections so as to satisfy the following equation You must set the height H ₀ of 12 _0. The width of air path is not restricted in practice, usually for using the width of the shielding plate 11 as a representative length, or less, using a L _e as the width of the air passage.

Cross-sectional area of air path = D · L _e (D is the height of the air path (see FIG. 2)) Cross-sectional area of projection = H ₀ · T _L Normally, to set _Le = T _L , and L _e = T _L in order to simplify the equation in the description.

{(Cross-sectional area of projection) / (Cross-sectional area of air path)} ≦ 0.5 (1) (H _{0 TL} ) / (D · L _e ) ≦ 0.5 H ₀ ≦ 0. 5D (2) Here, the numerical value of 0.5 on the right side of the equation (1) indicates that, if the cross-sectional area of the protrusion is 50% or less of the cross-sectional area of the air passage, the effect of the blockage of the flow by the protrusion (the air passage The effect of the large cross-sectional area of the projection on the cross-sectional area) is a value derived from the fact that it does not occur. There is a relationship as shown in FIG.

[0028] Next, a description about setting the projection center-to-center distance S _n.

FIG. 6 shows the structure of the flow over the protrusion inside the protrusion valley. Fig. 6 (a)
As shown in FIG. 6, there is a stable vortex inside the valley between the protrusions, the mixing phenomenon of the flow near the wall surface is not activated, and if the protrusion interval is appropriate as shown in FIG. It was determined by experiments that the mixing phenomenon was activated.

5 × (H _n-1 + H _n ) ÷ 2 ≦ S _n ≦ 13 × (H _n-1 + H _n ) ÷ 2 (3) However, if H ₀ = H, it depends on the flow rate. It was found that the mixing phenomenon of the flow near the wall surface was activated.

Here, (H _n-1 + H _n ) ÷ 2 indicates the average height of two adjacent protrusions.

Since there is a relationship as shown in FIG. 7 between the air volume and the thermal efficiency, it is desirable to install a fan having a large capacity as much as space permits to improve the cooling efficiency.

If H ₀ = H is determined, then H _n is determined.
, Which is H from FIG. 8 showing the height of the n-th protrusion.
_It suffices to find _n (in FIG. 8, only the value of the representative protrusion height reduction coefficient K is plotted, but K = 0.87 or the like may be used). At this time, the projection height reduction coefficient K is determined by the value of the projection height reduction coefficient K based on the position of the fan and the maximum angle at which the louver moves, the interval between the projections to be attached (if the interval is determined, the number of projections to be arranged is determined), and the like. May be selected, but it is desirable to use the largest possible value of the projection height reduction coefficient K in order to increase the surface area as much as possible.

The general formula for obtaining the n-th projection height H _n is as following equation.

H _n = K · H _{n -1} (4) where H ₀ = H By substituting equation (4) into equation (3), the following equation is obtained.

5 × (1 + K) H _n−1 ÷ 2 ≦ S _n ≦ 13 × (1 + K) H _n−1 ÷ 2 (5) Here, note that H ₀ = H. ), A coefficient to be multiplied by the average height (1 + K) H _n-1 ÷ 2 of two adjacent protrusions 5, 13
Is, for example, that once determined to be 5, it must be kept at 5 (S ₁ = 5 × (1 + K) H ÷ 2, S ₂
= 7 × (1 + K) H ₁ ÷ 2, S ₃ =...

[0037] In Thus, the height H ₀ was determined as described above, H _1, H protrusion 12 ₀ with _2, 12 _1, 12 ₂
Are attached to the shielding plate 11 at the intervals S ₁ and S ₂ , the cooling efficiency of the shielding plate 11 can be increased.

As shown in FIG. 9, the projections 12 ₀ , 12 ₁ and 12 ₂ may be mounted on the shielding plate 11 upside down from the case shown in FIG.

Also, as shown in FIG. 10, if the position of the fan 13 in FIG.
The projection height H _n is K = 1 as _{H 0 = H 1 = H 2} = H 3 =
... well as H _n = H, this time equation (5) is as follows.

5H ≦ S ≦ 13H (6) As described above, if there is sufficient space in the apparatus and one fan can be installed for one heat source, the louver is always used without swinging up and down. It is sufficient to cool the device by sending air uniformly, but the louvers may be swung up and down. And this is the same is true for the case where with the projections 12 _0, 12 _1, 12 ₂ as shown in FIG.

When the configuration shown in FIG. 2 or FIG. 9 is adopted, if the position of the fan 13 becomes the illustrated position due to the space of the apparatus, if it is not necessary to cool other parts, The louver 13a is desirably fixed so that the wind flows in the direction shown in the figure.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. FIG.
1 is a cross-sectional view showing a configuration of a shielding plate with a projection according to the present embodiment, and FIG. 12 is a view in the direction of arrow A in FIG.

When the mounting position of the fan 13 described in the first embodiment is changed as shown in FIG. 11 (here, the position of the fan 13 in FIG. 2 is changed, but in another example of the first embodiment, The same is true), and it was experimentally found that the equation (2) becomes as follows.

H ₀ ≦ 0.95D (7) The following can be considered as a reason why the equation (2) is replaced with the equation (7) by changing the mounting position of the fan 13.

That is, as shown in FIG. 12, unlike the flow in the duct, the air present in the portions indicated by B and C is also discharged, so that it is considered that the influence of the blockage is small.

[0046] As expression (7), to set the height H ₀ of the top corners of the projections 12 _0, protrusion spacing to satisfy equation (5) S
Setting _n (projections 12 _0, 12 _1, 12 ₂ of the spacing S _1, S _2), it was found that activated mixing phenomenon of flow in the vicinity of the wall surface without depending on the flow rate.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a view showing various cross-sectional shapes of the projection.

[0048] Figure 13 instead of the protrusion having a square cross section of side length H _n described in the first and second embodiments (a) ~ (e)
Can be used.

[0049] The center-to-center distance S _n for projections of each cross-sectional shape be determined by the following equations respectively in the same format as the formula (5) was confirmed experimentally.

Semi-elliptical shape (FIG. 13 (a)): 6 × (1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 10 × (1 + K) H
_n-1 ÷ 2, where H ₀ = H semicircular (FIG. 13B): 5 × (1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 11 × (1 + K) H
_n-1 ÷ 2 where H ₀ = H triangle A (FIG. 13 (c)): 5 × (1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 13 × (1 + K) H
_n-1 ÷ 2, where H ₀ = H triangle B (FIG. 13D): 5 × (1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 13 × (1 + K) H
_n-1 ÷ 2 where H ₀ = H triangle C (FIG. 13E): 5 × (1 + K) H _n-1 ÷ 2 ≦ S _n ≦ 13 × (1 + K) H
_n-1 ÷ 2 where it was found that mixing phenomenon of flow in the vicinity of the wall surface without depending on the flow rate by setting the center-to-center distance S _n projections as above H ₀ = H is activated.

The shielding plate with projections according to the present invention is not limited to the embodiment described above, but can be variously modified within the scope of the invention.

[0052]

As is apparent from the above description, according to the present invention, the cooling efficiency of the projection-equipped shielding plate is improved by arranging a plurality of projections having a predetermined height and a sectional shape at optimal intervals. Is obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an image forming apparatus provided with a shielding plate with projections according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged cross-sectional view of the periphery of the projection-equipped shielding plate of the image forming apparatus including the projection-equipped shielding plate according to Embodiment 1 of the present invention;

FIG. 3 is a diagram showing a wind direction of a fan.

FIG. 4 is a perspective view of the shielding plate with projections according to Embodiment 1 of the present invention.

FIG. 5 is a diagram showing a relationship between a blockage rate and thermal efficiency.

FIG. 6 is a cross-sectional view illustrating a flow of air in a protrusion valley.

FIG. 7 is a diagram illustrating a relationship between an air volume and a cooling efficiency.

FIG. 8 is a diagram showing an n-th projection height when a projection height reduction coefficient K is changed.

FIG. 9 is a diagram showing another embodiment of the method of arranging the projections on the shielding plate with projections according to the first embodiment of the present invention.

FIG. 10 is a diagram showing a special example of the shielding plate with protrusions according to Embodiment 1 of the present invention.

FIG. 11 is a cross-sectional view of a shielding plate with projections according to Embodiment 2 of the present invention.

12 is a view in the direction of arrow A in FIG. 4;

FIG. 13 is a view showing various cross-sectional shapes of a protrusion according to the third embodiment.

FIG. 14 is a longitudinal sectional view of an image forming apparatus including a conventional shielding plate.

[Explanation of symbols]

11 Shielding plate with projections 12 _{0 to} 12 ₂ projections H _n projection height K projection height reduction coefficient S _n projection spacing

Claims (4)

[Claims] 1. An interval S _n : 5 × (1 + K) H _n -1 which is obtained by the following formula, in which three or more protrusions having a square cross section and a height H _n are substantially perpendicular to the flow direction of air. 2 ≦ S _n ≦ 13 × (1 + K) H
_n-1 ÷ 2, where H ₀ = H, K: a projection height reduction coefficient, and a shielding plate with projections. 2. An interval S _n : 6 × (1 + K) H _{n− which is} obtained by obtaining three or more protrusions having a semi-elliptical cross section and having a height H _n substantially at right angles to the direction of air flow by the following equation. ₁ ÷ 2 ≦ S _n ≦ 10 × (1 + K) H
_n-1 ÷ 2, where H ₀ = H, K: a projection height reduction coefficient, and a shielding plate with projections. 3. An interval S _n of three or more protrusions having a semicircular cross section and having a height H _n and substantially perpendicular to the direction of air flow, obtained by the following equation: S _n : 5 × (1 + K) H _{n -1} ÷ 2 ≦ S _n ≦ 11 × (1 + K) H
_n-1 ÷ 2, where H ₀ = H, K: a projection height reduction coefficient, and a shielding plate with projections. 4. A distance obtained by substantially perpendicularly equation three or more projections of height H _n having a triangular cross-section with respect to the flow direction of the air _{S n: 5 × (1 +} K) H n-1 ÷ 2 ≦ S _n ≦ 13 × (1 + K) H
_n-1 ÷ 2, where H ₀ = H, K: a projection height reduction coefficient, and a shielding plate with projections.