JP2006002675A - Liquid driving device, cooling device, liquid driving method, cooling method, thermal fixing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid drive method without using a mechanically operated pump, a pump operated by electric power, and its device, for example, cooling by effectively utilizing heat from a fixing device equipped in an image forming apparatus, for example. By circulating the liquid for use, the exhaust heat from the fixing device can be efficiently recovered and discharged to the outside.
SOLUTION: A first flow path 101 filled with a liquid and a second flow path 110 that communicates with the first flow path and is filled with a liquid are provided, and heat of an external heating element is used. Then, the liquid in the second flow path is heated to the boiling point or higher and then cooled, and the pressure vibration generated by alternately repeating the vaporization and aggregation of the liquid in the second flow path Liquid driving means 102 for allowing the liquid to flow in one direction.
[Selection] Figure 1

Description

  The present invention relates to a liquid flow technique that realizes liquid circulation in a closed flow path without using a mechanical drive mechanism that causes an increase in size, and a cooling device using the liquid flow technique. In particular, in electrophotographic image forming apparatuses such as copying machines, printers, MFPs, etc., this occurred in the fixing process when a toner image formed on a photoreceptor was transferred onto a recording sheet and then fixed by a thermal fixing device. The present invention relates to a technology that can be applied to a cooling technology that suppresses various obstacles that are generated when heat is propagated to other units in the apparatus or an internal temperature is increased.

For devices with heat sources such as heat generating units and heat generating parts in the housing, such as various electronic devices, communication devices, mechanical devices, etc., due to mechanical action such as sliding of the mechanical components when operating Heat generation or heat generation due to Joule heat in a motor or an electrical component is performed. Self-heating by a heat source provided in such a device itself may cause malfunctions such as malfunction or failure of other units or parts in the device, and deterioration of durability. Means are essential. As a conventional cooling method, natural air cooling that devises a heat dissipation structure, forced air cooling with a fan, or liquid cooling with a liquid refrigerant has been performed for a long time.
In recent electronic devices such as personal computers, power consumption increases in proportion to the improvement in CPU performance, and thus more effective cooling technology is required. In conventional cooling methods, forced air cooling by fans is the mainstream, and in order to improve the cooling capacity, it is necessary to rely on an increase in the number of fans and the number of fans. Noise is also a cause of impairing the comfort of the installation environment.
In order to cope with this problem, Japanese Unexamined Patent Application Publication No. 2003-124670 discloses a notebook personal computer equipped with a cooling device using liquid circulation. However, a pump that operates by general power supply is used for the liquid drive for circulation. For this reason, it is difficult to cope with downsizing of devices.

In addition, since most of image forming apparatuses using an electrophotographic system employ a heat fixing device, the temperature inside the apparatus is likely to rise further in addition to self-heating by heat-generating parts such as a motor, a power supply, and an electrical component. Various configurations for efficient cooling have been proposed in the past. Specifically, in order to prevent internal temperature rise by the heat fixing device, which is the largest heat source, and temperature rise of other units, the internal structure has been devised to secure multiple cooling fans and air flow paths. ing. Problems caused by an increase in internal temperature due to heat radiation from the heat fixing device include a toner fixing phenomenon in an image forming process before the fixing process. In recent years, toner with a lower melting point than before has been used to save energy, and the fixing unit and image forming unit have been placed closer together for colorization and equipment miniaturization, thus cooling the interior efficiently. It is difficult to prevent toner sticking.
For example, in Japanese Patent Laid-Open No. 2000-227730, an air flow path is formed on a fixing device, warmed air inside the air flow path is discharged to the outside by a fan and external cold air is taken in, and the fixing device is transferred to another unit. A technique for suppressing the heat transfer is disclosed.
Japanese Patent Application Laid-Open No. 11-235855 solves the above problem by circulating the coolant with a pump and utilizing a heat pipe. Further, the liquid in the heat pipe effectively absorbs heat from the fixing device by heat of vaporization.
Next, Japanese Patent No. 26739777 uses a periodic phase change (vaporization and agglomeration) of a liquid, and generates a fluid transfer pressure generation method that generates pressure for pumping a fluid without a mechanical moving part. It is invention regarding. In this invention, three heating sections are provided in the middle of the liquid flow path, and the pump operation is realized by carrying out the evaporation and aggregation of the liquid by heating at these three locations using a periodic control having a phase difference. is doing.
JP 2003-124670 A JP 2000-227730 A JP 11-235855 A Japanese Patent No. 267397

From the viewpoint of downsizing the equipment and the comfort of the installation environment, Japanese Patent Application Laid-Open No. 2000-227730 requires air to be blown through a narrow flow path at a high flow rate. If taken widely, the size of the equipment cannot be satisfied. In the inventions disclosed in Japanese Patent Laid-Open Nos. 2003-124670 and 11-235855 related to cooling by liquid circulation, the fan noise problem is solved, but the number of parts is used because a pump is used for liquid circulation. While the increase in size causes an increase in size and cost, most of the heat from the fixing device is discharged outside the apparatus and is wasted. In particular, the pump includes a mechanical mechanism, and if it is intended to increase its durability, the pump is increased in size and disadvantageous for reducing the size of the entire device, and if the pump is reduced in size, the durability is deteriorated. Further, when the power supply to the pump is interrupted or fails, the liquid circulation is interrupted, so that the reliability is lowered.
In Japanese Patent No. 26739777, since it is necessary to control a plurality of heating units in order to realize vaporization / aggregation, not only the control is complicated, but also exhaust heat from the fixing device is used. The waste heat is wasted. From the viewpoint of using exhaust heat, a liquid driving method based on a simple principle that does not use phase control is desirable.
Therefore, the present invention provides a pump that operates by electric power, a liquid driving method that does not use other mechanical mechanisms, and an apparatus thereof, for example, by effectively using heat from a fixing device provided in an image forming apparatus. By circulating the cooling liquid, the exhaust heat from the fixing device can be efficiently recovered and discharged to the outside.

In order to solve the above-described problem, a liquid driving apparatus according to the invention of claim 1 includes a first flow path filled with a liquid, and a second flow as a closed flow path communicating with the first flow path and filled with the liquid. A passage is provided, and the liquid in the second flow path is heated above its boiling point using the heat of the external heating element and then cooled to alternately repeat the vaporization and aggregation of the liquid in the second flow path. And a liquid driving means for causing the liquid in the first flow path to flow in one direction by the pressure vibration generated by the above.
A cooling device according to a second aspect of the invention is a cooling device using the liquid driving device according to the first aspect, comprising a plurality of heat exchangers along the first flow path, and at least one heat exchange. The heat of the external heating element is absorbed into the liquid in the first flow path by the chamber, and the heat of the liquid that has been heated is radiated to the outside of the first flow path by another heat exchanger.
A liquid driving method according to a third aspect of the present invention is a liquid driving method for forming a flow in a liquid filled in a first flow path, wherein the sealed flow path communicates with the first flow path and is filled with liquid. As the liquid in the second flow path is heated to the boiling point or higher and then cooled, the pressure vibration generated by repeating the vaporization and liquefaction of the liquid in the second flow path causes It is characterized by forming a flow in the liquid.
The cooling method according to the invention of claim 4 includes a plurality of heat exchangers along the first flow path, and absorbs the heat of the external heating element into the liquid in the first flow path by at least one heat exchanger, The heat of the heated liquid is radiated to the outside of the first flow path by another heat exchanger.

According to a fifth aspect of the present invention, in the second aspect, the cross-sectional area of the first flow path or the second flow path is not uniform in a rectifying unit that connects the flow paths. .
The invention of claim 6 is characterized in that, in claim 2, the two end portions of the first flow path are connected to the rectifying unit from a bent direction.
The invention of claim 7 is characterized in that, in claim 2, 5 or 6, the liquid driving means comprises a preheating device for generating Joule heat.
According to an eighth aspect of the present invention, in the second, fifth, sixth, or seventh aspect, the external heating element and the object to be cooled are a heat fixing device of an image forming apparatus.
A ninth aspect of the present invention relates to a thermal fixing device for an image forming apparatus, comprising the cooling device according to the second, fifth, sixth, or seventh aspect.
A tenth aspect of the present invention relates to an image forming apparatus comprising the cooling device according to the second, fifth, sixth, or seventh aspect.
An eleventh aspect of the present invention relates to an image forming apparatus, wherein the cooling device according to the eighth aspect is assembled to a heat fixing device, and the heat fixing device is detachable from the image forming device.
A twelfth aspect of the present invention relates to an image forming apparatus having the cooling device according to the eighth aspect, further comprising a fan for blowing air to a heat exchanger provided in the first flow path.

According to the present invention, pressure fluctuation due to vaporization and aggregation of the liquid is generated in the closed container (second flow path), and the container is connected to the first flow path in which the liquid is contained, thereby the first Liquid drive that allows the liquid in the flow path to flow in one direction was realized. That is, the closed end of the second flow path is continuously heated to boil and vaporize the liquid inside, while the other end of the second flow path is agglomerated by cooling the liquid. Therefore, the discharge and suction of the liquid from the open end are alternately repeated, and this serves as a drive source for driving the liquid in the first flow path in communication. The vaporization and aggregation can be realized with a simple structure and a low-cost structure without mechanical moving parts without using any special control. Moreover, a liquid cooling device using the liquid drive was realized.
Since operating energy is heat, if it is applied to a heat generating part that generates a temperature above the boiling point of the liquid, no electricity is required (or a power saving effect is obtained), and exhaust heat is used to save energy and global warming Effective in prevention. Moreover, since the heat of vaporization is taken away by the liquid drive, a heat insulation effect can be obtained by converting heat energy into kinetic energy.
In addition, in the liquid cooling device driven by electric power, the liquid cooling function is impaired when the power switch is turned off when the machine is stopped, or due to a power failure or failure of the power supply unit, but this liquid cooling device is driven by heat, Such a problem is solved.
The liquid cooling device of the present invention has the greatest merit that no electric power is used, but does not operate when the temperature of the heat source to be used is low. Therefore, heat for assisting this is supplied from electric power. However, an energy saving effect can be obtained even in view of the fact that the heat is effectively used and the power loss of the mechanical drive unit is reduced in total.
Among the electrophotographic image forming devices, by using this cooling device for devices that use the thermal fixing method, it is possible to use the exhaust heat from the fixing device and to cool the device to prevent internal temperature rise. It was. Conventionally, the exhaust heat of the fixing device has been dealt with by a large number of fan blowers. In other words, electric power is used to secure the fixing temperature, and extra electric power is used to prevent the heat diffusion. The fan noise impairs office comfort. On the other hand, in the present invention, the number of fans can be reduced by using a part of the exhaust heat portion effectively and liquid cooling by this device, and power saving and quietness can be realized.
In addition, even if an unforeseen situation that leads to an increase in the temperature inside the machine due to power interruption occurs, if the fixing device is in a high temperature state, the liquid driving means can be driven using the heat, so the liquid cooling device The effect of lowering the temperature inside the machine was obtained.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 is a schematic configuration diagram showing an overall configuration of a liquid cooling apparatus 100 using a liquid driving apparatus according to an embodiment of the present invention.
The liquid cooling device (cooling device) 100 is not shown as a first flow channel 101 filled with a liquid (refrigerant) to be driven, and as a closed flow channel communicating with the first flow channel 101 and filled with liquid. A liquid driving unit that includes the second flow path 110 and causes the liquid in the first flow path 101 to flow in one direction by heating the liquid in the second flow path 110 using the heat of the heating element (heat source). 102, and the liquid driving means 102 uses the heat from the external heating element to heat a part of the liquid in the second flow path 110 to a temperature equal to or higher than its boiling point. The liquid in the heated portion is vaporized, and the heated liquid is cooled and aggregated (liquefied) in another portion (non-heated portion) in the second flow path. Then, pressure vibrations generated by alternately repeating this vaporization and aggregation (heating the liquid in the second flow path and cooling the heated liquid in the second flow path using the heat of the external heating element) Thus, the liquid in the first flow path is driven by forming a liquid flow between the second flow path and the first flow path. Then, a plurality of heat exchangers 103 and 104 are arranged along the first flow path 101, and the heat exchanger 103 absorbs the heat of a specific heat generation site (cooling target) into the liquid, and the temperature of the liquid heated by the endotherm is increased. The heat to be cooled is cooled by dissipating heat to the outside of the first flow path 101 by another heat exchanger 104.
That is, in FIG. 1, water and other cooling liquids are filled (filled) in the first flow path 101 constituted by a tube made of a metal material such as copper or aluminum having high thermal conductivity. In other words, it is structured to flow in one direction when driven by the liquid driving means 102. In the middle of the piping path of the first flow path 101, the heat exchanger 103 (103a, 103b) and the heat exchanger 103 that absorb heat from the object to be cooled (for example, the heat generation part of the fixing device) absorb heat from the object to be cooled. There are other heat exchangers 104 and tanks 107 that dissipate the heat transferred by the liquid to the outside. Although the tank 107 is not essential, it is effective when venting the gas generated inside the liquid, and has a structure in which the tank is opened to the atmosphere or sealed with a gas at a predetermined pressure.

To the heat exchanger 104 for heat dissipation, a structure (fin or the like) 105 having a large surface area is joined (welded or pressure-bonded via thermal conductive grease) in order to improve heat dissipation efficiency. If natural air cooling using the structure 105 cannot sufficiently dissipate heat, forced air cooling by the fan 106 is performed.
As means for circulating the liquid in the first flow path 101, in the present invention, the liquid driving means 102 having the second flow path 110 is connected to an appropriate position of the flow path 101. By placing the heat exchanger 103 in, close to, or in close contact with the space or member (cooling target) to be cooled, the heat absorbed by the heat exchanger 103 from the cooling target is transferred to the heat exchanger 104 via the liquid. Liquid cooling becomes possible by radiating heat from there to the outside.
The liquid driving means 102 includes a second flow path 110 that is in communication with the first flow path 101 and is a sealed flow path that is filled with liquid. The liquid driving means 102 performs liquid driving using an expansion pressure due to the vaporization of the liquid and a contraction pressure when the liquid is vaporized from the vaporization. Since this principle is generally known as a toy poppo ship, the principle will be described with reference to FIGS. 2 (a), (b) and (c).

First, as shown in FIG. 2A, a structure body 152 made of a metal pipe filled with water is attached to the ship body 151 floated on the water 150, and the closed end of the structure body 152 is closed with a candle 153. Heat the part. The lower end portion of the structure 152 in the water is open. The structure 152 is made of a pipe such as aluminum or copper, and is made of a short tube, a U-shaped tube, a U-shaped tube in which a portion to be heated is wound in a coil shape, a plate having a hollow inside, or the like.
When the tip of the structure is heated to the boiling point of water by the candle 153, the liquid in the tip is vaporized and sudden volume expansion occurs, so that water is released from the lower open end of the structure 152 to the outside. This change in momentum imparts thrust to the ship and advances the ship (FIG. 2 (b)).
Next, the vapor generated by the vaporization of water in the structure 152 agglomerates and decreases the internal pressure by contacting the low temperature part of the tube, but the pressure drop due to the aggregation fluctuates more slowly than at the time of vaporization. Therefore, the structure 152 can slowly suck the water 150 from the lower open end and does not retreat. By repeating the operations of FIGS. 2B and 2C, the ship moves forward. This is the principle of the Pompon Ship.
The liquid driving means 102 of the present invention has a configuration for causing the liquid in the first flow path 101 to flow in one direction using this principle. The structure 152 corresponds to the second flow path 110 of the present invention, and the candle 153 corresponds to, for example, a heat fixing device. In the present invention, the water discharged or sucked from the lower end opening of the structure 152 is introduced into the first flow path 101 via a rectifying section described later, and the liquid in the first flow path 101 is made to flow. The driving force is circulated in the direction.
In the present invention, it is necessary to make the vibration flow unidirectional as shown in FIGS. In order to generate such a unidirectional flow, in the present invention, rectification is performed using a flow resistance of a general flow path or a valve.

Next, FIGS. 3A and 3B are explanatory views of the configuration of an example of the liquid driving means of the present invention.
In this embodiment, due to the change in the cross-sectional area of the tube constituting the first flow channel 101, from the bottom to the right at the time of vaporization in FIG. The rectifying effect is obtained. In addition, the long arrow and the small arrow in a figure have shown the difference of the direction of flow from each pipe body, and flow volume. Thus, the liquid cooling circulation direction is one direction from the left to the right, and the second flow path 110 corresponding to the structure 152 in FIG. 2 and the first flow path 101 are coupled by the rectifying unit 114a. The left pipe body 101a of the first flow path has a pipe diameter that tapers toward the rectifying section at the joint with the rectifying section 104a, and the right pipe 101b is separated from the joint with the rectifying section 104a. The pipe diameter is expanding in the direction. The second flow path 110 is connected to the rectifying unit 104a at a position orthogonal to the left and right tubular bodies 101a and 101b extending linearly.
The second flow path 110 is heated by placing an end (not shown) in contact with the outer surface of the heat fixing device, for example, and the internal liquid is heated to the boiling point to evaporate. The liquid in the two flow paths flows into the rectifying unit 114a as shown in FIG. At this time, since the tube diameters of the tube bodies 101a and 101b are set non-uniformly as illustrated, the liquid in the first flow path 101 flows in the right direction.
Next, when the vapor in the second flow path 110 starts to agglomerate in contact with the low temperature portion of the tube body, the internal pressure in the second flow path decreases, so that the liquid in the rectifying section 104a flows as shown in (b). Suction is performed toward the second flow path, and the liquid flows from the left tubular body 101a toward the right tubular body 101b along with the suction. As shown by a small arrow in FIG. 3B, a flow toward the rectifying unit is also formed from the right side tube body 101b. However, since the flow rate from the left side tube body 101a is overwhelmingly large, as a result The flow goes from right to left.

Next, FIGS. 4A and 4B are schematic configuration explanatory views of a liquid driving unit according to another embodiment. In this embodiment, the tubes 101c and 101d constituting the first flow path 101 are rectifying units. It is connected in a positional relationship orthogonal (bent) to 114b. The second flow path 110 is connected to the rectifying unit 114b at a position facing the output-side tube body 101d. Furthermore, the distal end of the tubular body constituting the second flow path 110 enters the rectifying unit 114b and is reduced in diameter to a taper shape. Furthermore, the tubular body 101d facing the second flow path 110 is enlarged in a taper shape in a direction away from the rectifying unit 114b. In addition, the other pipe body 101c has a diameter that increases in a tapered shape toward the rectifying unit at a portion connected to the rectifying unit 114b.
In the above configuration, at the time of vaporization shown in FIG. 4A, the liquid is pushed out from the second flow path 110 into the right tube 101d in the right direction. At the time of aggregation shown in FIG. 4B, since suction is performed in a direction returning to the second flow path 110, the liquid is sucked from the lower tube body 101c by fluid resistance and into the right tube body 101d. Flows along a bent route.

Next, FIGS. 5A and 5B are schematic explanatory diagrams of the liquid driving means according to another embodiment of the present invention. This embodiment is characterized by a configuration in which a check valve is arranged in the rectifying unit.
In other words, the second flow path 110 is connected to the rectifying unit 114c in the point that the first flow path 101 is configured by the left and right tubular bodies 101a and 101b extending linearly and in a positional relationship orthogonal to the first flow path 101. This is the same as FIG. The rectifying unit 114c of this embodiment includes left and right chambers 114c-1 and 114c-2, and check valves 115a and 115b made of floating spheres are provided in the chambers 114c-1 and 114c-2. Stoppers 116a and 116b for restricting the movement range of the stop valve are arranged. The check valve 115a moves due to the pressure difference from each flow path, and opens and closes the left tube 101a. The check valve 115b moves due to a pressure difference from each flow path, and opens and closes the right pipe body 101b or the flow path connected to the right pipe body 101b. In addition, a bypass pipe 117 is connected between the left pipe body 101a and the second flow path 110 (the inner space of the rectifying unit below the diaphragm). Further, a diaphragm 118 as shown in the figure is disposed in the chamber 114c-1, and the chamber 114c-1 is partitioned vertically.
The rectifying unit according to this embodiment operates on the same principle as that used for a diaphragm pump or a water hammer pump. At the time of vaporization in FIG. 5 (a), the pressurized liquid is introduced from the second flow path 110 into the first chamber 114c-1, so that the diaphragm 118 is deformed upward as shown in FIG. The check valve 115a closes the inlet of the left tube 101a, and the check valve 115b opens the flow path to the right tube 101b. For this reason, at the time of vaporization, the liquid is pushed out into the right tube 101b, and the flow of the liquid from the left tube 101a is stopped by the operation of the check valve 115a. At the time of aggregation in FIG. 5B, the diaphragm is deformed downward by suction from the second flow path 110, so that the right check valve 115b stops the inflow from the right tube 101b, while the left reverse valve The stop valve 115a is opened, the liquid flows into the rectifying unit from the left pipe body 101a, and is driven from the left to the right in the flow path.
By alternately repeating the discharge and suction operations for the rectifying unit due to the vaporization and aggregation, the liquid can flow in one direction from the tube body 101a to the tube body 101b.

Next, FIGS. 6A and 6B are explanatory diagrams of a schematic configuration of a liquid driving unit according to another embodiment of the present invention. This embodiment is the same as the embodiment of FIG. 5 in the configuration in which the check valve is arranged in the rectifying unit, but does not use a diaphragm.
At the time of vaporization in FIG. 6A, since the liquid flows into the rectifying unit 14d from the second flow path 110, the check valve 115a closes the inflow side pipe body 101c, while the check valve 115b has a stopper 116b. The tube body 101d on the outflow side is opened by being locked by.
On the other hand, at the time of aggregation in FIG. 6B, since the liquid is sucked into the second flow path 110, the check valve 115a opens the inflow side tube 101c and introduces the liquid into the rectifying unit 114d. Thus, the check valve 115b closes the outflow side pipe body 101d.
By alternately repeating the discharge and suction operations for the rectifying unit due to the vaporization and aggregation, the liquid can flow in one direction from the tube body 101c to the tube body 101d.
FIG. 6 is basically the same principle as FIG. 5 except that there is no diaphragm. Here, if the upper side of the figure is aligned with the vertical upper side, the upper check valve 115b can close the flow path when dropped due to gravity, so that the liquid drive with gravity assistance is possible.
In each of the embodiments described above, pressure fluctuation due to liquid vaporization and aggregation occurs in the sealed container (second flow path), and the second flow path as the sealed container is connected to the first flow path in which the liquid is located. By doing so, the liquid drive which flows the liquid in this 1st flow path to one direction was realizable. The vaporization and aggregation can be realized with a simple structure and a low-cost structure without mechanical moving parts without using any special control. Moreover, a liquid cooling device using the liquid drive was realized. Since operating energy is heat, if it is applied to a heat generating part that generates a temperature above the boiling point of the liquid, no electricity is required (or a power saving effect is obtained), and exhaust heat is used to save energy and global warming Effective in prevention. Further, since the heat of vaporization is taken away by the liquid drive, a heat insulation effect can be obtained by converting the heat energy into kinetic energy.

Next, FIG. 7 is a schematic diagram showing a configuration example in which a preheating unit is added to the configuration of the liquid driving apparatus (liquid driving unit) shown in FIG.
In this embodiment, by adding the preheating means 120 to the second flow path 110, the liquid drive that is insufficient with only the heat generated from the heat generating unit and the heat generating component (main heating source) in the apparatus such as the image forming apparatus. Can make up for the amount of heat. That is, the preheating unit 120 has a resistance heating element 121 that generates heat by electric power attached to the second flow path 110, and is connected by a conducting wire 122 via a power supply connector 123. In this way, by using Joule heat to vaporize and liquefy the liquid in the second flow path 110, the liquid can be driven by the above principle, and a liquid cooling device can be realized.
Since the preheating means 120 is used so as to supplementarily heat when the amount of heat from a main heating source such as a heat fixing device is insufficient, for example, a thermometer 124 and a lead connector are provided in the heating portion of the second flow path 110. 125 is connected to a voltage device (power source) 126 that can control the voltage applied to the heating resistor 121 according to the detected temperature from the thermometer 124.
Depending on the application place and application conditions of the cooling device of the present invention, liquid circulation may be realized by driving the liquid driving means using only heat generation using the heating resistor.
In the liquid-cooled apparatus driven by electric power shown in FIG. 7, the liquid-cooled function is impaired when the power switch is turned off when the machine is stopped, or due to a power failure or a failure of the power supply unit. Therefore, such a problem is solved. The liquid cooling device of the present invention has the greatest merit that no electric power is used, but does not operate when the temperature of the heat source to be used is low. Therefore, heat for assisting this is supplied from electric power. However, an energy saving effect can be obtained even in view of the fact that the heat is effectively used and the power loss of the mechanical drive unit is reduced in total.

Next, an example in which the liquid cooling apparatus and the liquid cooling method of the present invention are used in an image forming apparatus using a thermal fixing system will be described.
FIG. 8 is a schematic configuration diagram of an example of a color image forming apparatus to which the present invention is applied. An image forming apparatus 1 is disposed substantially at the center of the color image forming apparatus, and is supplied immediately below the image forming section 1. A paper part 2 is arranged. The paper feed unit 2 includes a paper feed cassette 21 at each stage. If necessary, another sheet feeding device (not shown) can be provided. Above the image forming unit 1, a reading unit (reading optical system) 3 for reading a document image is disposed. On the left side of the image forming unit 1, a paper discharge storage unit 4 is disposed, and the transfer sheet on which the image is formed is discharged and stored. In the image forming unit 1, an intermediate transfer belt 5 as a belt-like intermediate transfer member is stretched endlessly along a predetermined traveling path, and is driven in the direction of an arrow by each support roller. Four image forming units 6 are arranged along the upper running surface of the intermediate transfer belt 5. In each image forming unit 6, a charging device 62 that charges the surface of the photosensitive member around the drum-shaped photosensitive member 61, an exposure device 7 that irradiates the surface of the photosensitive member with laser light, and a photosensitive member. A developing device 63 for visualizing the electrostatic latent image formed on the surface of the toner and a cleaning device 64 for removing and collecting the toner remaining on the photosensitive member are disposed. As an image forming process, intermediate transfer is performed. The belt 5 rotates to form one color image. First, yellow (Y) toner is developed and transferred to the intermediate transfer belt in the yellow (Y) image forming section. Next, the magenta (M) image forming unit develops the magenta toner and transfers it to the intermediate transfer belt. Next, in the cyan (C) image forming section, cyan toner is developed and transferred to the intermediate transfer belt, and finally, black (BK) toner is developed and transferred to the intermediate transfer belt. On the lower running surface of the intermediate transfer belt 5 that is different from the upper running surface of the intermediate transfer belt to which each image forming unit 6 is close, four color toner images transferred onto the intermediate transfer belt are transferred onto the transfer paper. A transfer device (paper transfer device) 51 for transferring paper and an intermediate transfer cleaning device 52 for removing and collecting toner remaining on the surface of the intermediate transfer belt after transfer are arranged.

A fixing device (fixing unit) 8 for fixing the toner image by passing the transfer paper on which the transfer toner image has been transferred by the transfer device 51 is disposed. The transfer sheet that has passed through the fixing device 8 is discharged and stored in the discharge storage unit 4 by the discharge roller 41.
In the paper supply unit 2, unused transfer paper is stored in the paper supply cassette 21, and the bottom plate that is rotatably supported raises the uppermost transfer paper to a position where the pickup roller can contact. Due to the rotation of the paper feed roller, the uppermost paper is sent out from the paper feed cassette and conveyed to the registration roller 23. The registration roller 23 is controlled so as to start rotation at a timing so that the transfer of the transfer paper is temporarily stopped and the positional relationship between the toner image on the surface of the photosensitive member and the leading edge of the transfer paper is a predetermined position. In the reading unit 3, in order to read and scan a document (not shown) placed on the contact glass 31, the reading traveling bodies 32 and 33 including a document illumination light source and a mirror reciprocate. Image information scanned by the reading traveling bodies 32 and 33 is read as an image signal into a CCD 35 installed behind the lens 34. The read image signal is digitized and subjected to image processing. Based on the image-processed signal, an electrostatic latent image is formed on the surface of the photoreceptor 61 by light emission of a laser diode LD (not shown) in the exposure device 7. The optical signal from the LD reaches the photosensitive member via a known polygon mirror or lens. An automatic document feeder 36 for automatically feeding a document onto the contact glass is attached above the reading unit 3.
The cooling device 100 is attached in a structure that covers the outer surface of the case above the sheet passing path of the fixing device as shown in FIG. In addition, the cooling device 100 is attached to the fixing device 8 supported so as to be able to advance and retreat in the front-rear direction by a rail (not shown) disposed on the device main body side so that it can be pulled out from the inside of the device together with the fixing device. The cooling device works with either method. However, in the latter case, the maintenance of the liquid cooling device 100 becomes very easy.

FIG. 9A is a front longitudinal sectional view showing a configuration example in which the cooling device 100 is attached to the fixing device 8. A liquid driving device is attached to an exterior member (not shown) of the fixing device, and the first flow path 101. Was mounted across the heat insulating material 130 and the liquid driving means 102. The liquid driving unit 102 includes a second flow path 110, and the heat radiated from the fixing device is effectively used by bringing the heating portion of the second flow path 110 into close contact with the heat generating portion on the outer surface of the fixing device 8. It is comprised so that the liquid in a 2nd flow path can be heated to a boiling point. Further, the first flow path 101 absorbs exhaust heat radiated by coming into contact with other portions of the outer surface of the fixing device.
FIG.9 (b) is the perspective view which looked at Fig.9 (a) from the upper right upper part. The first flow path 101 is configured by bending a copper or aluminum pipe, and the first flow path unit is configured by attaching the first flow path 101 to a plate member 131 made of copper or aluminum. As a method of attaching the first flow path 101 to the plate member 131, it is possible to employ a method of fixing through a bracket, applying heat conductive grease on the contact surface to increase heat absorption efficiency, or welding. The efficiency of heat transfer can be further improved.
As shown in FIG. 9 (b), a part of the back side of the first flow path is bent and attached to the back side surface of the fixing device 8, and the fins 105 are placed on the surface of the plate 131 via the heat conductive grease. Screwed to the back. A cooling fan that promotes heat dissipation in the fins 105 was installed on the apparatus main body side (not shown). The heat radiation from the fixing cover is absorbed by the plate member 131, and is dissipated by the fins 105 when the heated liquid in the channel 101 is transferred. The gear 132 on the side surface of the fixing cover is a means for obtaining a driving force from the apparatus main body in order to rotationally drive the roller in the fixing unit.
FIG. 9C shows another example of the configuration of the first flow path unit. The first flow path unit is a plate member made of copper or aluminum having a hollow inside and provided with a partition defining the flow path. 133. According to this, since the amount of fluid (total volume of the flow path) occupying the plate area is increased, the heat absorption efficiency is higher than that of the first flow path unit of FIG. 9B using the pipe material. Connection with the liquid drive unit 102 disposed on the lower surface side of the first flow path unit is performed by the joint unit 134.

Next, FIGS. 10A and 10B are bottom views of an example of the second flow path 110 in which the liquid vaporizes and aggregates, as viewed from the lower part (fixing device side). In FIG. 10A, a thin copper pipe 142 having a diameter of 2 mm and a thick copper pipe 141 having a diameter of 5 mm are connected to the surface of the copper substrate 140. That is, the thin copper pipe 142 is connected and communicated in parallel with the side portion of the thick copper pipe 141, and the ends other than the connecting portion of each pipe are sealed and filled with liquid. The thick copper pipe 141 is connected to the rectifying unit 114 at one end, and is connected to the first flow path 101 of FIG. 9B or FIG. 9C via a joint part 143 (143a, 143b) provided in the rectifying unit 114. It is connected.
The second flow path 110 shown in FIG. 10 (b) has a configuration in which the inside of the copper plate 133 shown in FIG. 9 (c) is divided into a plurality of small flow paths communicating with each other by a partition plate 135. I have. The small flow path includes a common flow path 110a and a branch flow path 110b, and communicates with the rectifying unit 114 at one end of the common flow path 110a.
Each of the second flow paths shown in FIGS. 10A and 10B takes heat from the fixing device and vaporizes a part of the liquid inside. Since the liquid driving unit 102 is disposed obliquely with respect to the direction of gravity as shown in FIG. 9A, the gas generated by boiling the liquid gathers in the diagonally upper sealed portion (FIG. 2B). )reference). Thereby, the liquid inside the second flow path 110 is pushed out to the opposite side and moves toward the rectifying unit 114. As shown in the examples of FIGS. 3 to 6, the liquid flows into and out of the rectifying unit 114 by repeating the gasification and aggregation of the liquid in the second flow path 110, and as shown in the examples of FIGS. 3 to 6. The liquid can flow in one direction within the 101.

As shown in FIG. 9, a heat insulating material 130 (130a) is inserted between the liquid driving means 102 and the fixing device 8. This heat insulating material 130a is not shown in FIG. Only the copper pipe 141 is insulated. That is, since the fine copper pipe 142 is in direct contact with the cover of the fixing device, the liquid inside can be boiled by receiving heat. When vapor vaporized in the fine copper pipe 142 comes into contact with the low temperature liquid and the first flow path 101 in the rectifying unit 114 from the thick copper pipe 141, the vapor is condensed. As a result, pressure vibration was generated, liquid driving was possible, and a liquid cooling device could be realized. Also in FIG. 10B, the liquid circulation was smoothed by insulating the portion (common flow path 110a) corresponding to the thick copper pipe 141 in FIG. 10A.
The liquid to be used may be water, distilled water, or an aqueous solution in which ethyl alcohol or ammonia is dissolved.
Thus, in the present invention, among the electrophotographic image forming apparatuses, by using this cooling device for a device using a thermal fixing method, exhaust heat from the fixing device is used and measures against an internal temperature rise of the device are taken. Cooling for can be realized. Conventionally, the exhaust heat of the fixing device has been dealt with by a large number of fan blowers. In other words, electric power is used to secure the fixing temperature, and extra electric power is used to prevent the heat diffusion. The fan noise impairs office comfort. On the other hand, in the present invention, the number of fans can be reduced by using a part of the exhaust heat portion effectively and liquid cooling by this device, and power saving and quietness can be realized.
Further, even when an unexpected situation that would lead to an increase in the temperature inside the machine due to the power stoppage, if the fixing device is at a high temperature, the liquid cooling device is activated to lower the temperature inside the machine.

1 is a schematic configuration diagram illustrating an overall configuration of a liquid cooling apparatus 100 using a liquid driving apparatus according to an embodiment of the present invention. (A) (b) And (c) is a figure explaining the principle of this invention. (A) And (b) is a figure explaining the operating principle of the liquid drive means which concerns on one Embodiment of this invention. (A) And (b) is a figure explaining the operating principle of the liquid drive means which concerns on other embodiment of this invention. (A) And (b) is a figure explaining the operating principle of the liquid drive means which concerns on other embodiment of this invention. (A) And (b) is schematic structure explanatory drawing of the liquid drive means which concerns on other embodiment of this invention. Schematic which shows the structural example which added the preheating means with respect to the structure of the liquid drive device shown in FIG. 1 is a schematic configuration diagram of an example of a color image forming apparatus to which the present invention is applied. (A) is a front longitudinal sectional view showing a configuration example in which a cooling device is attached to a fixing device, (b) is a perspective view of FIG. 9 (a) seen from the upper right side, and (c) is a first flow path unit. The figure which shows the other structural example. (A) And (b) is the bottom view which looked at the Example of the 2nd flow path where the liquid vaporizes and aggregates from the lower part (fixing apparatus side), respectively.

Explanation of symbols

8 Heat fixing device (fixing unit), 100 Liquid cooling device (cooling device), 101 First flow path, 102 Liquid driving means, 103, 104 Heat exchanger, 105 Fin, 106 Fan, 107 Tank, 110 Second flow path , 110a common flow path, 110b common flow path, 114 rectification part, 115 check valve, 116 stopper, 118 diaphragm, 130 heat insulating material, 131 plate material, 133 plate member, 134 joint part, 141 heavy copper pipe, 142 fine copper pipe

Claims (12)

  A first flow path filled with a liquid; a second flow path as a sealed flow path that is in communication with the first flow path and filled with the liquid; The liquid in the first flow path flows in one direction by pressure vibration generated by heating the liquid above its boiling point and then cooling and alternately repeating the vaporization and aggregation of the liquid in the second flow path. And a liquid driving means.   The cooling device using the liquid driving device according to claim 1, comprising a plurality of heat exchangers along the first flow path, and a first flow of heat of the external heating element by at least one heat exchanger. A cooling device, wherein the liquid in the passage absorbs heat, and the heat of the heated liquid is radiated to the outside of the first flow path by another heat exchanger. In the liquid driving method for forming a flow in the liquid filled in the first flow path,
Vaporization of this liquid in the second flow path is achieved by heating the liquid in the second flow path as a sealed flow path communicating with the first flow path and filled with liquid to the boiling point or higher and then cooling. A liquid driving method characterized by forming a flow in the liquid in the first flow path by pressure vibration generated by repeating the liquefaction and the liquefaction.   A plurality of heat exchangers are provided along the first flow path, the heat of the external heating element is absorbed by the liquid in the first flow path by at least one heat exchanger, and the heat of the heated liquid is exchanged with another heat. A cooling method, characterized in that heat is radiated to the outside of the first flow path by a vessel.   The cooling device according to claim 2, wherein a flow path cross-sectional area of the first flow path or the second flow path is not uniform in a rectifying unit that connects the flow paths.   The cooling device according to claim 2, wherein two end portions of the first flow path are connected to the rectifying unit from a bent direction.   The cooling device according to claim 2, 5 or 6, wherein the liquid driving means includes a preheating device for generating Joule heat.   The cooling device according to claim 2, 5, 6, or 7, wherein the external heating element and the object to be cooled are a heat fixing device of an image forming apparatus.   A thermal fixing device for an image forming apparatus, comprising the cooling device according to claim 2, 5, 6, or 7.   An image forming apparatus comprising the cooling device according to claim 2, 5, 6, or 7.   An image forming apparatus, wherein the cooling device according to claim 8 is assembled to a heat fixing device, and the heat fixing device is detachable from the image forming device. The image forming apparatus having the cooling device according to claim 8, further comprising a fan for blowing air to a heat exchanger provided in the first flow path.

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