JP2010204571A - Cooling apparatus and image forming apparatus - Google Patents

Abstract

The present invention provides a cooling device that can equalize the flow velocity of the air flow on the downstream side of the duct even when a bent portion is provided on the upstream side of the duct, thereby improving the cooling efficiency without increasing the flow resistance. An image forming apparatus is provided.
A duct 310 is formed in a bent shape in accordance with the position and shape of a fixing unit and a heat pipe, an intake port 312 is provided at one end, and an exhaust port 314 is provided at the other end. . The blower flow path 340 located downstream of the bent portion 330 is provided with a throttle structure 350 and a blower 320, and the fan 322 of the blower 320 is driven to rotate, and air sucked from the intake port 312 is sucked. It passes through the air flow path 340 and the throttle structure 350 in the duct 310 and is discharged from the exhaust port 314. A cooling object 360 is inserted downstream and is cooled by an air flow. The throttle structure 350 suppresses unevenness in the velocity distribution of the air flow in the downstream channel 344 and increases the cooling efficiency for the cooling target 360.
[Selection] Figure 3

Description

  The present invention relates to a cooling device that efficiently cools an object to be cooled in a duct, and an image forming apparatus including the cooling device.

  For example, in an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a multifunction machine having a facsimile function and a copying function, the temperature rise in the machine may cause malfunction of the device, so the internal heat source is cooled. A cooling device is installed.

  For example, in an image forming apparatus such as a copying machine, image quality deteriorates due to heat transfer from a fixing unit that fixes an image on a recording medium, self-heating of a developing portion, toner fusion at a site outside the fixing, paper A paper jam or the like due to curling of the paper occurs.

  In order to prevent such abnormalities due to heat, air flow generated by a fan or the like is directly applied to a heat generating part or to a heat radiating fin connected to the heat generating part with a heat conductor (heat pipe) having a high heat transfer coefficient. A cooling device is provided for cooling.

  In addition, in the cooling device, for example, (1) to reduce the number of fans, (2) to take in fresh air from outside the machine, (3) to perform reliable exhaust to the outside, (4) extra Ducts are installed in the machine (inside the casing) for various reasons, such as to prevent toner scattering due to wind sneaking.

  For example, as a cooling device, a common main duct is arranged for a plurality of heat sources, and a duct structure in which air heated from each heat source flows into the main duct, and a uniform temperature inside the machine with a small number of fans. There are some which aim at reduction (for example, refer to patent documents 1).

  In addition, as another cooling device, there is one in which a heat radiation fin connected by a heat source and a heat pipe is arranged in a duct, and the heat radiation fin is cooled by air blown from a fan arranged before and after the heat radiation fin ( For example, see Patent Document 2).

  As another cooling device, the tunnel effect is used to efficiently cool and exhaust with a small number of fans, and a layout assuming a cooling flow path in the vertical direction is used. There is one that supplies an air flow to the air (see, for example, Patent Document 3).

  In any case of the above Patent Documents 1 to 3, if an attempt is made to arrange a duct structure in the machine, the duct itself cannot be secured due to a reduction in the size of the machine (miniaturization, space saving), etc. The flow path has a complicated shape, and the duct system path from the intake port to the exhaust port repeatedly bends.

  However, in the cooling device, by providing a bent portion in the duct, the fluid resistance in the duct increases and the fan blowing efficiency decreases, and further, the flow (flow velocity) in the duct becomes uneven and the fan blows. There is a problem that the efficiency is lowered or the cooling target such as the fins of the heat pipe is not uniformly applied with the air flow, and the cooling efficiency does not increase.

  In view of the above circumstances, an object of the present invention is to provide a cooling device and an image forming apparatus that have solved the above-described problems.

In order to solve the above problems, the present invention has the following means.
(1) The present invention relates to a cooling device having a duct in which an object to be cooled is arranged in an air flow path, and an air blowing device that generates an air flow in the air flow path of the duct.
In the portion located upstream of the object to be cooled, a throttle structure in which an upstream throttle portion that throttles the cross-sectional area of the flow path, a throttle minimum opening, and a downstream throttle portion is provided continuously,
The diaphragm structure is
The channel cross-sectional area S1 of the minimum aperture is set to 1/2 to 3/4 of the channel cross-sectional area S2 upstream of the upstream throttle portion and downstream of the downstream throttle portion,
The throttle height from the position of the inner wall of the duct to the minimum aperture of the throttle is H, the length of the upstream throttle portion in the flow path extending direction is L1, and the length of the downstream throttle portion in the flow path extending direction When L2 is L2, the lengths L1 and L2 are set to 2 × H to 4 × H.
(2) The present invention is characterized in that the diaphragm structure is formed by continuously forming curved surfaces having different curvature radii.
(3) In the present invention, the throttle structure is characterized in that a plurality of curved surfaces or flat surfaces having different inclination angles are continuously formed on the inner surface of the air flow path of the duct.
(4) The present invention relates to a cooling object to which heat generated in the process of transferring and fixing a toner image to a recording medium, a duct in which the cooling object is inserted, and air in an air flow path of the duct. An image forming apparatus having a cooling device for generating a flow,
In the portion located upstream of the object to be cooled, a throttle structure is provided in which an upstream throttle portion that throttles a flow path cross-sectional area, a throttle minimum opening, and a downstream throttle portion are continuous,
The diaphragm structure is
The channel cross-sectional area S1 of the minimum aperture is set to 1/2 to 3/4 of the channel cross-sectional area S2 upstream of the upstream throttle portion and downstream of the downstream throttle portion,
The throttle height from the position of the inner wall of the duct to the minimum aperture of the throttle is H, the length of the upstream throttle portion in the flow path extending direction is L1, and the length of the downstream throttle portion in the flow path extending direction When L2 is L2, the lengths L1 and L2 are set to 2 × H to 4 × H.

  According to the present invention, even if a bent portion is provided on the upstream side of the duct, it is possible to increase the cooling efficiency without increasing the flow resistance by equalizing the flow velocity of the air flow on the downstream side of the duct.

1 is a longitudinal sectional view showing a schematic configuration of an embodiment of an image forming apparatus provided with a cooling device according to the present invention. It is a perspective view for demonstrating the frame structure and duct chamber of the housing | casing of an image forming apparatus. It is a longitudinal cross-sectional view which shows typically the cooling device attached to the image forming apparatus. It is a longitudinal cross-sectional view which expands and shows the duct structure of the cooling device shown in FIG. It is a longitudinal cross-sectional view which shows typically the modification 1 of a cooling device. It is a longitudinal cross-sectional view which expands and shows the duct structure of the modification 1. It is a longitudinal cross-sectional view which shows the modification 2 of a cooling device typically. It is a longitudinal cross-sectional view which expands and shows the duct structure of the modification 2. It is a longitudinal cross-sectional view which shows the modification 3 of a cooling device typically.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an embodiment of an image forming apparatus provided with a cooling device according to the present invention. The image forming apparatus can be applied to a copying machine, a facsimile apparatus, a printer apparatus, a multifunction machine having a facsimile function and a copying function, and the like.

  As shown in FIG. 1, the image forming apparatus 10 is a high-speed multifunction peripheral, and an automatic document feeder 12 that conveys a document to a reading position, a scanner unit 13 that reads the document, and a recording sheet in a housing 11. A developing unit 14 that forms a toner image (visible image) on a (recording medium), image data read by the scanner unit 13 and a photoreceptor 15 on which toner is transferred onto the image data, and photosensitive The transfer unit 16 that transfers the toner image transferred to the body 15 onto the recording paper, the toner fixing unit 17 that thermally fixes the toner image onto the recording paper, and the recording paper for image formation are housed. And a paper feeding unit 18 for feeding the paper.

  In this embodiment, the scanner unit 13, the developing unit 14, the photosensitive member 15, the transfer unit 16, and the toner fixing unit 17 constitute an image forming unit.

  As shown in FIG. 2, the housing 11 has a skeleton composed of support columns 20 erected on the bottom plate 19 and beam members 21 interconnecting them. A duct chamber 22 is provided on the back side of the casing 11, and a rear plate 28 of the casing 11 is located between them.

A cooling device 300 is disposed in the duct chamber 22. The duct chamber 22 has a front side defined by a rear plate 28 of the housing 11 and a rear side covered by an exterior cover 29 of the duct chamber 22. A heat pipe 32 for cooling the transfer paper discharged from the fixing unit 17 is inserted into the installation hole 30 provided in the rear plate 28 of the housing 11. The heat pipe 32 is attached so as to rotate in sliding contact with the recording paper when the recording paper discharged from the toner fixing unit 17 is cooled.
Furthermore, a heat radiating fin (an object to be cooled) that is cooled by the cooling device 300 disposed in the duct chamber 22 is attached to the rear end portion of the heat pipe 32.

  Here, the configuration of the cooling device 300 will be described.

  As shown in FIG. 3, the cooling device 300 includes a duct 310, a blower 320, and a throttle structure 350. The duct 310 is formed in a bent shape according to the position and shape of the fixing unit 17 and the heat pipe 32, and the air inlet 312 is provided at one end and the air outlet 314 is provided at the other end. Further, the flow path from the intake port 312 to the exhaust port 314 is provided with a bent portion 330 bent at a right angle in an L shape. The bent portion 330 is often provided at a plurality of locations depending on the positional relationship with the peripheral device, but in the present embodiment, for convenience of explanation, a configuration provided with only one location will be described as an example.

  The blower channel 340 located downstream of the bent portion 330 is provided with a throttle structure 350 and a blower 320. The fan 322 of the blower 320 is driven to rotate, and air sucked from the intake port 312 is sucked. It passes through the air flow path 340 and the throttle structure 350 in the duct 310 and is discharged from the exhaust port 314. Further, a cooling object 360 is inserted into the flow path downstream of the blower 320. In the present embodiment, the cooling object 360 is, for example, a heat radiating fin of the heat pipe 32 (see FIG. 2) coupled to the paper discharge side roller of the fixing unit 17.

  In the air flow path 340 in the duct 310, the air flow that flows in from the intake port 312 flows as follows when passing through the bent portion 330. The air flow Fa in the vicinity of the inner corner 334 does not flow according to the shape of the inner corner 334, but once peeled off at the inner corner 334 and collides with the opposing inner wall of the duct, the air flow Fa follows the wall from the outer corner 332. Therefore, the velocity distribution of the airflow flowing through the flow path 340 is not constant. That is, since the air flow that has passed through the bent portion 330 is brought close to the outer portion due to peeling near the inner corner portion 334, the air flow Fa and the air flow Fb near the outer corner portion 332 have different flow velocities. Therefore, after the uniform flow at the intake port 312 passes through the bent portion 330, the air flow Fa at the inner corner portion 334 has a lower flow velocity, while the air flow Fb near the outer corner portion 332 is The flow rate becomes faster.

  As described above, when the velocity distribution of the air flow flowing through the upstream flow path 342 of the blower flow path 340 fluctuates irregularly, the cooling target 360 disposed in the downstream flow path 344 of the duct 310 is cooled. There is also a problem that the air flow has unevenness in the flow velocity, and the cooling efficiency with respect to the cooling target 360 is not constant.

  Therefore, in this embodiment, the configuration in which the throttle structure 350 is provided between the upstream flow path 342 and the downstream flow path 344 suppresses unevenness in the air flow velocity distribution in the downstream flow path 344. The cooling efficiency for the cooling object 360 is increased.

  Here, the configuration of the diaphragm structure 350 will be described with reference to FIG. As shown in FIG. 4, the throttle structure 350 is disposed under the duct 310 so that the flow passage cross-sectional area becomes gradually smaller than the flow passage cross-sectional area S2 of the upstream flow passage 342 toward the downstream (X direction). From the upstream throttle portion 370 having the side inner wall and the upper inner wall inclined, the minimum opening 380 having the smallest channel cross-sectional area, and the channel cross-sectional area S1 of the minimum opening 380 toward the downstream (X direction) In addition, a downstream throttle portion 390 in which the lower inner wall and the upper inner wall of the duct 310 are inclined so that the flow path cross-sectional area gradually increases.

  In the flow path extending direction (X direction) of the duct 310, the range from the throttle start position P1 to the minimum throttle position P2 is the upstream throttle portion 370, the minimum throttle position P2 is the minimum opening 380, and the minimum throttle position. The range from P2 to the stop end position P3 is the downstream stop portion 390.

  The upstream throttle portion 370 and the downstream throttle portion 390 are formed so as to be substantially symmetrical about the minimum opening portion 380 in the flow path extending direction, and the minimum opening portion 380 is downstream of the upstream throttle portion 370 and the downstream portion. It is formed by a triangular top connected to the side diaphragm portion 390.

  In the throttle structure 350 of the present embodiment, the length of the upstream throttle portion 370 in the X direction is L1, the length of the downstream throttle portion 390 in the X direction is L2, and the minimum is relative to the upstream flow path 342 and the downstream flow path 344. When the height dimension of the opening 380 is H, the ratio of each dimension is set as follows.

  The channel cross-sectional area S1 of the minimum aperture 380 is 50% to 75% (1/2 to 3/4) of the channel cross-sectional area S2 upstream of the upstream throttle portion 370 and downstream of the downstream throttle portion 390. It is desirable to set. Further, the length L1 of the upstream throttle portion 370 in the flow path extending direction (X direction) and the length L2 of the downstream throttle portion 390 in the flow path extending direction (X direction) are equal to the minimum opening 380 and the upstream. It is desirable that the height H of the side flow path 342 and the downstream flow path 344 is set to 2 to 4 times (2 × H to 4 × H). Further, the lengths L1 and L2 of the upstream throttle portion 370 and the downstream throttle portion 390 may be L1≈L2, so that, for example, L1 = 2H, L2 = 4H, or vice versa, L1 = It is good also as 4H and L2 = 2H.

  When an air blowing experiment was performed using the throttle structure 350 configured to satisfy the above conditions, the following experimental results were obtained. For example, the flow path cross-sectional area S1 of the throttle minimum opening 380 is set to be 60% of the flow path cross-sectional area S2, and the lengths L1 and L2 of the upstream and downstream throttle parts 390 of the upstream throttle part 370 are set. When the height H is set to twice the height H of the minimum opening 380 (2 × H), the air flow rate of the air flow path 340 is increased by 9% with respect to the case where no restriction is provided, and the amount of heat exhausted from the cooling target 360 is It was found to increase by 5%.

  That is, in the throttle structure 350, even if the flow velocity of the air flow flowing into the upstream flow path 342 from the bent portion 330 is not constant in the flow path cross-sectional area S2, the area between the upstream throttle portion 370 and the minimum opening 380 is between The flow velocity is accelerated in the process of passing through (the range from the aperture start position P1 to the minimum aperture position P2), and while passing through the downstream aperture portion 390 from the minimum opening 380 (from the minimum aperture position P2 to the aperture end position P3). In this range, the flow rate is rectified while being decelerated to make the flow velocity distribution uniform.

  For this reason, the air flow blown to the cooling target 360 disposed in the downstream flow path 344 is uniform in the cross-sectional area S2, so that any part of the surface of the cooling target 360 is cooled in the same manner. Thus, the cooling efficiency can be improved without increasing the flow path resistance. Therefore, in the downstream flow path 344 of the duct 310, the heat of the recording medium discharged from the fixing unit 17 can be efficiently taken from the heat pipe 32 and the cooling target 360 even if the bent portion 330 is provided upstream. Can do.

Here, a modified example will be described.
(Modification 1)
FIG. 5 is a longitudinal sectional view schematically showing Modification 1 of the cooling device. FIG. 6 is an enlarged longitudinal sectional view showing the duct structure of the first modification. 5 and FIG. 6, the same parts as those in the above-described embodiment are designated by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 5 and 6, the cooling device 300 </ b> A of Modification 1 is provided with a throttle structure 350 </ b> A having a continuous curve in the air flow path 340 </ b> A of the duct 310 </ b> A. The throttle structure 350A is an upstream side that narrows the lower inner wall and the upper inner wall of the duct 310A in a curved shape so that the cross-sectional area gradually becomes smaller than the cross-sectional area S2 of the upstream channel 342 toward the downstream (X direction). In order to gradually increase the cross-sectional area from the throttle portion 370A, the smallest opening 380A in which the flow passage cross-sectional area is most restricted, and the flow passage cross-sectional area S1 of the smallest opening 380A toward the downstream (X direction), And a downstream throttle portion 390A in which the lower inner wall and the upper inner wall of the duct 310A are widened in a curved shape.

  In the flow path extending direction (X direction) of the duct 310A, the range from the throttle start position P1 to the minimum throttle position P2 is the upstream throttle portion 370A, the minimum throttle position P2 is the minimum opening 380A, and the minimum throttle position The range from P2 to the stop end position P3 is the downstream stop portion 390A. In the first modification, the upstream throttle portion 370A, the minimum opening 380A, and the downstream throttle portion 390A are each formed in a continuous curved shape, and can guide the air flow into a smooth flow.

  That is, in the throttle structure 350A, the linear portion and the corner portion of the above-described embodiment are formed in a curved shape, and the upstream throttle portion 370A includes a curve R1 having a curvature radius r1 curved outward and a curvature curved inward. It has a curved surface formed continuously with a curve R2 having a radius r2. The minimum opening 380A has a curved surface with a minimum diameter by a curve R2 having a curvature radius r2. The downstream throttle portion 390A has a curved surface in which a curve R2 having a curvature radius r2 curved inward and a curve R3 having a curvature radius r3 curved outward are continuously formed.

  The upstream throttle portion 370A and the downstream throttle portion 390A are formed so as to be substantially symmetric with respect to the flow path extending direction around the minimum opening portion 380A. It is formed by a curved top connected to the side diaphragm portion 390A. The curvature radii r1, r2, and r3 are preferably set so that, for example, r1: r2: r3 = 1: 1: 1.

  In the throttle structure 350A of the first modification, the length of the upstream throttle portion 370A in the X direction is L1, the length of the downstream throttle portion 390A in the X direction is L2, the minimum opening 380A, the upstream flow path 342, and the downstream When the height dimension with respect to the side flow path 344 is H, the ratio of each dimension is set in the same manner as in the above embodiment.

  That is, the channel cross-sectional area S1 of the minimum aperture 380A is 50% to 75% (1/2 to 3/4) of the channel cross-sectional area S2 upstream of the upstream throttle portion 370A and downstream of the downstream throttle portion 390A. ) Is desirable. The length L1 of the upstream throttle portion 370A in the flow path extending direction (X direction) and the length L2 of the downstream throttle portion 390A in the flow path extending direction (X direction) are upstream of the minimum opening 380A. It is desirable that the height H of the side flow path 342 and the downstream flow path 344 is set to 2 to 4 times (2 × H to 4 × H). Further, the lengths L1 and L2 of the upstream throttle portion 370A and the downstream throttle portion 390A need only be L1≈L2, and for example, L1 = 2H and L2 = 4H may be set, or L1 = 4H and L2 = 2H may be set.

  When an air blowing experiment was performed using the throttle structure 350A configured to satisfy the above conditions, the following experimental results were obtained. For example, the cross-sectional area S1 of the minimum throttle opening 380A is set to be 60% of the flow path cross-sectional area S2, and the lengths L1 and L2 of the upstream and downstream throttle parts 390A of the upstream throttle part 370A are set to the minimum opening. When the height H of the portion 380A is set to twice (2 × H), the air flow rate of the air flow path 340A is increased by 12% compared to the case where no restriction is provided, and the amount of exhaust heat of the cooling target 360 is 7%. It turns out to rise.

  In other words, in the throttle structure 350A, even when the flow velocity of the air flow flowing from the bent portion 330 into the upstream flow path 342 is not constant in the flow path cross-sectional area S2, it is between the upstream throttle section 370A and the minimum opening 380A. The flow velocity is accelerated in the process of passing through (the range from the aperture start position P1 to the minimum aperture position P2), and while passing through the downstream aperture portion 390A from the minimum opening 380A (from the minimum aperture position P2 to the aperture end position P3). In this range, the flow rate is rectified while being decelerated to make the flow velocity distribution uniform.

Therefore, the air flow blown to the cooling target object 360 arranged in the downstream flow path 344 has the same flow velocity in the flow path cross-sectional area S2, so that any part of the surface of the cooling target object 360 is the same. Cooling efficiency can be improved without cooling and increasing the flow path resistance. Therefore, in the downstream flow path 344 of the duct 310A, the heat of the recording medium discharged from the fixing unit 17 can be efficiently taken from the heat pipe 32 and the cooling target 360 even if the bent portion 330 is provided upstream. Can do.
(Modification 2)
FIG. 7 is a longitudinal sectional view schematically showing a second modification of the cooling device. FIG. 8 is an enlarged longitudinal sectional view showing the duct structure of the second modification. 7 and 8, the same parts as those in the above-described embodiment are designated by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 7 and 8, in the cooling device 300B of the second modification, a throttle structure 350B in which a linear inclined surface is continuously changed while changing the angle is provided in the air flow path 340B of the duct 310B. In the throttle structure 350B, the lower inner wall and the upper inner wall of the duct 310B are linearly stepwise so that the sectional area gradually becomes smaller than the sectional area S2 of the upstream channel 342 toward the downstream (X direction). The cross-sectional area is gradually larger than the flow-path cross-sectional area S1 of the upstream-side throttle portion 370B to be throttled, the minimum opening 380B in which the flow-path cross-sectional area is most narrowed, and the upper minimum opening 380B toward the downstream (X direction). In order to become, it has the downstream side narrowing part 390B which expanded the lower side inner wall and upper side inner wall of the duct 310B in steps.

  In the flow path extending direction (X direction) of the duct 310B, the range from the throttle start position P1 to the minimum throttle position P2 is the upstream throttle portion 370B, the minimum throttle position P2 is the minimum opening 380B, and the minimum throttle position The range from P2 to the stop end position P3 is the downstream stop portion 390B. The upstream throttle portion 370B, the minimum opening portion 380B, and the downstream throttle portion 390B are formed by connecting portions La to Le each including a continuous linear portion or curved portion, and guide the air flow into a smooth flow. Can do.

  In the second modification example, the five connecting portions La to Le constitute a continuous diaphragm structure 350B while changing the angle with respect to the flow path extending direction (X direction) little by little. That is, the upstream throttle portion 370B is formed by the connection portions La and Lb, the minimum opening 380B is formed by the connection portion Lc, and the downstream throttle portion 390B is formed by the connection portions Ld and Le. Further, the inclination angle θa of the connection portion La of the upstream throttle portion 370B with respect to the flow path extending direction (X direction) and the inclination angle θb of the connection portion Lb are in a relationship of θa <θb. The inclination angle θd with respect to the flow path extending direction (X direction) of the connection portion Ld of the downstream throttle portion 390B and the inclination angle θe of the connection portion Le have a relationship of θe <θd. The angle of the minimum opening 380B with respect to the flow path extending direction (X direction) is zero.

  The restrictor structure 350B is formed such that the upstream restrictor portion 370B and the downstream restrictor portion 390B are substantially symmetrical about the minimum opening 380B in the flow channel extending direction, and the minimum opening 380B is horizontal. It is formed by a wall surface extending in the direction. Therefore, the diaphragm structure 350B has a trapezoidal central portion.

  Further, the length of the connecting portions La to Le in the flow path extending direction (X direction) is set to be, for example, La: Lb: Lc: Ld: Le = 1: 1: 1: 1: 1. It is desirable.

  In the throttle structure 350B of the second modification, the length in the X direction of the upstream throttle portion 370B is L1, the length in the X direction of the downstream throttle portion 390B is L2, the minimum opening 380B, the upstream flow path 342, and the downstream When the height dimension with respect to the side flow path 344 is H, the ratio of each dimension is set in the same manner as in the above embodiment.

  That is, the flow path cross-sectional area S1 of the minimum aperture 380B is 50% to 75% (1/2 to 3/4) of the flow path cross-sectional area S2 upstream of the upstream throttle part 370B and downstream of the downstream throttle part 390B. ) Is desirable. The length L1 in the flow path extending direction (X direction) of the upstream throttle portion 370B and the length L2 in the flow path extending direction (X direction) of the downstream throttle portion 390B are upstream of the minimum opening 380B. It is desirable that the height H of the side flow path 342 and the downstream flow path 344 is set to 2 to 4 times (2 × H to 4 × H). Further, the lengths L1 and L2 of the upstream side throttle portion 370B and the downstream side throttle portion 390B may be L1≈L2, for example, L1 = 2H and L2 = 4H, or L1 = 4H and L2 = 2H may be set.

  When an air blowing experiment was performed using the throttle structure 350B configured to satisfy the above conditions, the following experimental results were obtained. For example, the sectional area S1 of the throttle minimum opening 380B is set to be 60% of the channel sectional area S2, and the lengths L1 and L2 of the upstream throttle part 370B and the downstream throttle part 390B are set to the minimum opening. When the height H is set to twice the height H of the part 380 (2 × H), the air flow rate of the air flow path 340B is increased by 11% compared to the case where no restriction is provided, and the amount of exhaust heat of the cooling object 360 is 6%. It turns out to rise.

  That is, in the throttle structure 350B, even when the flow velocity of the air flow flowing from the bent portion 330 into the upstream flow path 342 is not constant in the flow path cross-sectional area S2, the distance between the upstream throttle portion 370B and the minimum opening 380B is The flow velocity is accelerated in the process of passing through (the range from the aperture start position P1 to the minimum aperture position P2), and while passing through the downstream aperture portion 390B from the minimum opening 380B (from the minimum aperture position P2 to the aperture end position P3). In this range, the flow rate is rectified while being decelerated to make the flow velocity distribution uniform.

Therefore, the air flow blown to the cooling target object 360 arranged in the downstream flow path 344 has the same flow velocity in the flow path cross-sectional area S2, so that any part of the surface of the cooling target object 360 is the same. Cooling efficiency can be improved without cooling and increasing the flow path resistance. Therefore, in the downstream flow path 344 of the duct 310B, the heat of the recording medium discharged from the fixing unit 17 can be efficiently taken from the heat pipe 32 even if the bent portion 330 is provided upstream.
(Modification 3)
FIG. 9 is a longitudinal sectional view schematically showing Modification 3 of the cooling device. In FIG. 9, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 9, in the cooling device 300 </ b> C of the third modification, the upstream flow path 342 of the duct 310 </ b> C is formed longer than the case of the above-described embodiment or the first and second modifications, and the upstream flow path 342. Is provided with a blower 320. A throttle structure 350C similar to the throttle structure 350 of the above embodiment is disposed on the downstream side of the blower 320, and a cooling object 360 is disposed in the downstream flow path 344 of the throttle structure 350C.

  Therefore, in the cooling device 300C, when the fan 322 of the blower 320 is rotationally driven, the air flow sucked from the air inlet 312 provided at one end of the duct 310C passes through the bent portion 330 and the upstream flow path 342. Then, the fan 322 further flows into the flow path 340 of the throttle structure 350C. Then, the air flow from the fan 322 passes through the throttle structure 350C and passes around the cooling target object 360 while taking heat of the cooling target object 360 and is discharged from the exhaust port 314.

  The air flow passing through the throttle structure 350C is accelerated in the process of passing between the upstream throttle portion 370 and the minimum opening 380 (range from the throttle start position P1 to the minimum throttle position P2), and further the minimum opening During the passage from the portion 380 to the downstream throttle portion 390 (range from the minimum throttle position P2 to the throttle end position P3), the flow velocity is rectified while being decelerated and the flow velocity distribution is made uniform. Therefore, the cooling target 360 disposed downstream of the throttle structure 350C is efficiently cooled. Therefore, even when the air blower 320 is provided at a location away from the cooling target 360, by providing the throttle structure 350C on the upstream side of the cooling target 360, the heat of the recording medium discharged from the fixing unit 17 can be reduced. The heat pipe 32 and the cooling object 360 can be efficiently taken away.

  In the above-described embodiment, the cooling device 300 is described as the cooling object 360 by using the heat dissipating fins of the heat pipe 32 for reducing the temperature of the recording medium P discharged from the fixing unit 17 as an example. Needless to say, the present invention can also be applied to cooling a heat conducting member other than a heat pipe.

  In addition, the present invention can be applied to the case where the heat generating unit (for example, the developing unit 80) other than the heat of the recording medium discharged from the fixing unit 17 of the image forming apparatus 10 is cooled. is there.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Case 12 Automatic document feeder 13 Scanner part 14 Developing part 15 Photoconductor 16 Transfer part 17 Toner fixing part 18 Paper feed part 19 Bottom plate 20 Strut 21 Beam material 22 Duct chamber 28 Rear side plate 29 Exterior cover 32 Heat Pipe 300, 300A-300C Cooling device 310, 310A-310C Duct 320 Blower 322 Fan 330 Bent part 312 Intake port 314 Exhaust port 330 Bent part 340, 340A-340C Blower channel 342 Upstream channel 344 Downstream channel 350 350A to 350C Restriction structure 360 Cooling object 370, 370A to 370C Upstream restriction part 380, 380A to 380C Minimum opening 390, 390A to 390C Downstream restriction part La to Le Connection part S1, S2

JP2003-208065 JP2007-015441 JP 2005-043579 A

Claims (4)

In a cooling device having a duct in which an object to be cooled is disposed in a blower flow path, and a blower that generates an air flow in the blow flow path of the duct,
In the portion located upstream of the object to be cooled, a throttle structure in which an upstream throttle portion that throttles the cross-sectional area of the flow path, a throttle minimum opening, and a downstream throttle portion is provided continuously,
The diaphragm structure is
The flow passage cross-sectional area S1 of the minimum throttle opening is set to 1/2 to 3/4 of the flow passage cross-sectional area S2 upstream of the upstream throttle portion and downstream of the downstream throttle portion,
The throttle height from the position of the inner wall of the duct to the minimum aperture of the throttle is H, the length of the upstream throttle portion in the flow path extending direction is L1, and the length of the downstream throttle portion in the flow path extending direction When L2 is L2, the lengths L1 and L2 are set to 2 × H to 4 × H.   The cooling device according to claim 1, wherein curved surfaces having different curvature radii are continuously formed in the throttle structure.   The cooling device according to claim 1, wherein the throttle structure has a plurality of curved surfaces or flat surfaces having different inclination angles formed continuously on the inner surface of the air flow path of the duct. A cooling object to which heat generated in the process of transferring and fixing a toner image to a recording medium is conducted; a duct in which the cooling object is inserted; and a cooling device for generating an air flow in the air flow path of the duct; An image forming apparatus having
In the portion located upstream of the object to be cooled, a throttle structure in which an upstream throttle portion that throttles the cross-sectional area of the flow path, a throttle minimum opening, and a downstream throttle portion is provided continuously,
The diaphragm structure is
The flow passage cross-sectional area S1 of the minimum throttle opening is set to 1/2 to 3/4 of the flow passage cross-sectional area S2 upstream of the upstream throttle portion and downstream of the downstream throttle portion,
The throttle height from the position of the inner wall of the duct to the minimum aperture of the throttle is H, the length of the upstream throttle portion in the flow path extending direction is L1, and the length of the downstream throttle portion in the flow path extending direction In the image forming apparatus, the lengths L1 and L2 are set to 2 × H to 4 × H, where L2 is L2.

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