JP2011085890A - Cooling device and image forming device - Google Patents

Abstract

A cooling device capable of reducing a temperature gradient in the axial direction of a cooling roller, and an image forming apparatus including the cooling device.
SOLUTION: A double tube structure including an inner tube in an outer tube, an outer channel through which a cooling medium flows between the outer tube and the inner tube, and an inner tube channel through which the cooling medium flows in the inner tube. Yes, a cooling roller rotatably supported on the housing of the apparatus main body via a bearing, a cooling medium conveying means for conveying the cooling medium, and attached to both ends of the cooling roller in a state where the cooling roller is rotatable, In a cooling device comprising a rotating pipe joint means for connecting a cooling roller and a cooling medium conveying means, the flow direction of the cooling medium conveyed to the outer flow path by the cooling medium conveying means in the outer flow path, and the cooling medium conveyance The flow direction of the cooling medium conveyed to the inner flow path by the means in the inner flow path is opposite to the cooling roller axial direction.
[Selection] Figure 1

Description

  The present invention relates to a cooling device for cooling a sheet-like member used in an image forming apparatus such as a printer, a facsimile machine, and a copying machine, and an image forming apparatus provided with the cooling device.

  2. Description of the Related Art As an image forming apparatus, an apparatus that forms a toner image on a sheet-like sheet using electrophotographic technology and melts and fuses the toner by passing through a thermal fixing device is known. In general, the temperature of the heat fixing device varies depending on the type of toner and paper, the paper conveyance speed, and the like, but is set and controlled at a temperature of about 180 ° C. to 200 ° C. to fuse the toner instantaneously. The surface temperature of the paper immediately after passing through the heat fixing device is a high temperature of about 100 ° C. to 130 ° C., for example, although it depends on the heat capacity (specific heat, density, etc.) of the paper. Since the melting temperature of the toner is lower, the toner is slightly soft at the time immediately after passing through the heat fixing device, and remains in a sticky state for a while until the paper cools down. Therefore, when the image output operation is repeated continuously and the paper after passing through the heat fixing device is stacked in the paper discharge container, if the toner on the paper cannot be sufficiently cured and is in a soft state, the toner on the paper A so-called blocking phenomenon that sticks to another sheet may occur and the image quality may be significantly reduced.

  In the image forming apparatus described in Patent Literature 1, a cooling device including a cooling roller that is rotatably supported by a bracket via a bearing and that cools the paper while contacting the paper and transporting the paper is more paper than the heat fixing device. It is provided on the downstream side in the transport direction. The paper after passing through the heat fixing device is cooled by the cooling roller of the cooling device, so that the toner on the paper is cooled and hardened, and the occurrence of the blocking phenomenon can be suppressed. The cooling roller has a double tube structure in which the inner tube is included in the outer tube, and an outer channel through which the coolant flows through the gap between the outer tube and the inner tube, and an inner channel through which the coolant flows in the inner tube. is there. Cooling liquid flows from the one end side to the other end side in the cooling roller axial direction through the outer flow path and the inner flow path, and the cooling roller whose temperature is increased by removing heat from the sheet is cooled by the cooling liquid. Further, by adopting a double-pipe structure for the cooling roller, the heat of the cooling liquid flowing through the outer flow path, which is received and warmed from the cooling roller, is received by the cooling liquid flowing through the inner flow path and flows through the outer flow path. Therefore, the cooling performance of the cooling roller can be improved. In the configuration in which the cooling liquid flows from the one end side to the other end side in the cooling roller axial direction through the outer flow path and the inner flow path in the cooling roller, the pump for supplying the cooling liquid and the cooling roller are connected via a pipe. A rotary joint is disposed at each end of the cooling roller.

  When the cooling liquid flows through the outer flow path from one end side to the other end side in the cooling roller axial direction, the temperature of the cooling liquid in the outer flow path is the lowest on the one end side, and the cooling roller moves from the sheet toward the other end side. The temperature of the coolant in the outer channel increases due to the heat absorbed by the. Further, when the coolant flows through the inner flow path from one end side to the other end side in the cooling roller axial direction, the temperature of the coolant in the inner flow path is the lowest on the one end side, and the outer stream flows toward the other end side. The temperature of the inner channel increases due to the heat absorbed from the coolant of the channel. Therefore, the temperature of the coolant in the outer channel increases from the one end to the other end, and the cooling efficiency of the coolant in the outer channel by the coolant in the inner channel decreases. The surface temperature is lowest on the one end side and highest on the other end side. For this reason, there arises a problem that a difference in the cooling efficiency of the sheet in the cooling roller axial direction is caused by the temperature difference in the cooling roller axial direction on the surface of the cooling roller. If there is a difference in the cooling efficiency for the paper in the cooling roller axis direction, the paper is cooled with a temperature gradient in the cooling roller axis direction. May occur. When the paper curls, paper jam is likely to occur in the paper conveyance path from the cooling device to the paper discharge accommodating portion.

  By the way, in recent years, as the image forming processing speed of an electrophotographic image forming apparatus has further increased, a recording medium such as a sheet is continuously fed as in a printing process and continuously for a long time (for example, several days). Accordingly, electrophotographic image forming apparatuses have come to be used for image forming processing (printing processing). Such an electrophotographic image forming apparatus, for example, can perform image forming processing of about 100 to 120 sheets per minute with A4 paper, and is called a so-called high-speed machine. Such an image forming apparatus (high-speed machine) also includes a cooling device including a cooling roller as described above in order to prevent a blocking phenomenon particularly after passing through the heat fixing device as the image forming process speeds up. ing. An image forming apparatus provided with such a cooling device is configured to perform image forming processing (printing processing) continuously for a long time (for example, several days) as described above. For this reason, the temperature difference in the axial direction of the cooling roller as described above becomes more conspicuous by continuous paper passing, and problems such as curling of the paper are likely to occur. Accordingly, it has been desired to reduce the temperature difference in the axial direction of the cooling roller, particularly in a high-speed machine.

  SUMMARY An advantage of some aspects of the invention is that it provides a cooling device capable of reducing a difference in cooling efficiency with respect to a sheet generated in the axial direction of a cooling roller, and an image forming apparatus including the cooling device. It is to be.

In order to achieve the above object, an invention according to claim 1 includes an outer pipe that encloses an inner pipe in an outer pipe, a cooling medium flows between the outer pipe and the inner pipe, and cooling the inner pipe. A cooling pipe having a double pipe structure having an inner pipe flow path through which a medium flows, rotatably supported by a housing of the apparatus main body via a bearing, a cooling medium carrying means for carrying a cooling medium, and the cooling roller Are attached to both ends of the cooling roller in a rotatable state, and a rotating pipe joint means for connecting the cooling roller and the cooling medium conveying means, and a sheet-like member is brought into contact with the cooling roller to form a sheet In the cooling device for cooling a member, the flow direction of the cooling medium conveyed to the outer flow path by the cooling medium conveying means in the outer flow path, and the cooling conveyed to the inner flow path by the cooling medium conveying means The inner flow path of the medium And the flow direction of the is characterized in that in the opposite direction in the cooling roller axis direction.
According to a second aspect of the present invention, in the cooling device of the first aspect, both ends of the outer pipe are rotatably supported by the rotary pipe joint means, and both ends of the inner pipe are fixed to the rotary pipe joint means. It is characterized by being supported.
According to a third aspect of the present invention, in the cooling device of the first aspect, both ends of the outer pipe and both ends of the inner pipe are rotatably supported by the rotary pipe joint means. .
According to a fourth aspect of the present invention, in the cooling device of the first, second, or third aspect, the cooling medium is conveyed by the cooling medium conveying means common to the outer flow path and the inner flow path. Is.
The invention of claim 5 is characterized in that, in the cooling device of claim 1, 2, or 3, the cooling medium is transferred to the outer flow path and the inner flow path by the respective cooling medium transfer means. To do.
The invention of claim 6 is the cooling device of claim 1, 2, 3, 4 or 5, characterized in that the same cooling medium circulates in the outer channel and the inner channel. .
The invention of claim 7 is characterized in that, in the cooling device of claim 1, 2, 3, 4 or 5, different cooling media circulate in the outer channel and the inner channel, respectively. is there.
The invention according to claim 8 is the cooling device according to claim 1, 2, 3, 4, 5, 6 or 7, further comprising a cooling medium stirring means for stirring the cooling medium between the outer tube and the inner tube. It is characterized by providing.
The invention according to claim 9 is the cooling device according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein a cooling medium agitating means for agitating the cooling medium is provided in the inner tube. It is what.
The invention according to claim 10 is the cooling device according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein both ends of the outer pipe are the first of the rotary pipe joint means. The inner pipe is attached so as to be coaxially rotatable in the fitting portion, and both ends of the inner pipe are coaxially fitted to the second fitting portion of the rotary pipe joint means and can be rotated or fixed. It is characterized by being supported by.
The invention according to claim 11 is a toner image forming means for forming a toner image on a sheet-like member, and a heat fixing means for fixing the toner image formed on the sheet-like member to the sheet-like member at least by heat. And a cooling unit that cools the sheet-like member on which the toner image has been fixed by the thermal fixing unit, wherein the cooling unit is the claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 cooling devices are used.

In the present invention, the flow direction of the cooling medium flowing through the outer flow path and the flow direction of the cooling medium flowing through the inner flow path are opposite to each other in the cooling roller axial direction. When flowing from one end side to the other end side, the cooling medium is flowed from the other end side to the one end side in the inner flow path. As a result, the cooling liquid in the outer flow path can be cooled by the cooling liquid in the inner flow path whose temperature is lower at the other end side where the temperature of the cooling liquid in the outer flow path becomes higher due to the heat absorbed by the cooling roller from the paper. it can.
When the cooling medium is flowed from the other end side to the one end side in the outer flow path, the cooling medium is flowed from the one end side to the other end side in the inner flow path. Thereby, the coolant of the outer channel can be cooled by the coolant of the inner channel having a lower temperature toward the one end side where the temperature of the coolant of the outer channel becomes higher due to the heat absorbed by the cooling roller from the paper. .
Therefore, the cooling roller axial direction of the coolant flowing in the outer flow path is different from the conventional configuration in which the flow direction of the cooling medium flowing in the outer flow path is the same as the flow direction of the cooling medium flowing in the inner flow path. The temperature difference can be reduced. Accordingly, the temperature difference in the cooling roller axial direction on the surface of the cooling roller is reduced accordingly, so that the difference in cooling efficiency with respect to the sheet generated in the cooling roller axial direction can be reduced.

  As described above, according to the present invention, there is an excellent effect that it is possible to reduce the difference in cooling efficiency with respect to the sheet generated in the axial direction of the cooling roller.

The schematic sectional drawing of the cooling device provided with the cooling roller of a double tube structure. The schematic sectional drawing of the cooling roller which attached the double type rotary joint which is a rotary pipe joint means to both ends. The enlarged view of the cooling roller left end part. The enlarged view of a cooling roller right end part. Explanatory drawing used for description of assembly of a cooling roller. Explanatory drawing used for description of assembly of a cooling roller. Explanatory drawing used for description of assembly of a cooling roller. The schematic sectional drawing of the cooling roller which attached the double type rotary joint which is a rotary pipe joint means to both ends. The enlarged view of the cooling roller left end part. The enlarged view of a cooling roller right end part. Explanatory drawing used for description of assembly of a cooling roller. Explanatory drawing used for description of assembly of a cooling roller. Explanatory drawing used for description of assembly of a cooling roller. The schematic sectional drawing of a cooling roller when the coil spring as a stirring means is closely attached to the inner wall of a roller pipe | tube. The schematic diagram of the circulation system of a cooling fluid. The schematic diagram of the circulation system of a cooling fluid. The schematic diagram of the circulation system of a cooling fluid. FIG. 2 is a schematic configuration diagram of a tandem type intermediate transfer belt type color image forming apparatus equipped with a cooling roller having a double-pipe structure cooling roller and a cooling liquid circulation system. FIG. 2 is a schematic configuration diagram of a tandem type intermediate transfer belt type color image forming apparatus equipped with a cooling roller having a double-pipe structure cooling roller and a cooling liquid circulation system.

  Embodiments of the present invention will be described. The cooling roller and the cooling device of the present invention will be described in a state where the cooling roller and the cooling device are mounted on an image forming apparatus in which toner on a recording sheet (sheet medium) is fixed by a heat fixing unit. However, the cooling roller and the cooling device of the present invention are not limited thereto, and can be applied to any device that requires cooling of the sheet medium. In the present embodiment, a liquid is used as a cooling medium. However, a gas may be used as long as it is a fluid medium. The cooling roller as the cooling means of this embodiment has a tubular structure, and cools the surface of the cooling roller by flowing and circulating a cooling liquid therein. Then, the cooling device having the cooling roller is disposed in the sheet conveyance path immediately after the heat fixing unit. The cooling roller not only has a function of removing heat from the sheet, but also needs to be in direct contact with the sheet for removing the heat, and thus has a function as a conveying roller for conveying the sheet.

  FIG. 1 is a schematic diagram of an example of a cooling roller 22B and a cooling device 18B having a double-pipe structure that also serves to convey a sheet.

  The cooling device 18B is provided with rollers 30 and 31 arranged at intervals in the conveyance direction (left-right direction) of the paper P, and the conveyance belt 32 for paper conveyance is extended. Then, using the roller 30 on the downstream side in the paper transport direction as a drive roller (connected to a drive source not shown), the transport belt 32 is rotated counterclockwise to transport the paper from the right side to the left side in the drawing. Although not shown, the heat fixing means 16 is disposed on the upstream side (right side in the figure) of the cooling device 18B, and the paper discharge accommodating portion 17 is located on the downstream side (left side in the figure). An upper guide 33A for guiding the paper P conveyed from the heat fixing means 16 is provided above the roller 31. An intermediate position between the roller 30 and the roller 31 is provided from above so as to bite into the conveying belt 32. A cooling roller 22B having a double-pipe structure is in pressure contact, and is rotated along with the conveyance force of the conveyance belt 32. Reference numeral 34 in the drawing denotes a bracket that constitutes the main body of the cooling device 18B, and is a member that supports component parts such as the roller 30, the roller 31, the cooling roller 22B, and the upper guide 33A so as to be fixed or rotatable. The cooling device 18B is unitized by the bracket 34 and incorporated in the image forming apparatus.

  The paper P heated to a high temperature by the heat fixing means 16 passes through the cooling device 18B before being discharged to the paper discharge accommodating portion 17. More specifically, the sheet P that has reached a high temperature through the heat fixing means 16 enters between the upper guide 33A and the roller 31, passes through the nip region formed by the cooling roller 22B and the conveying belt 32, and stores the discharged paper. It is discharged to the part 17. Since the paper P passes through the nip region in close contact with the cooling roller 22B, the heat of the paper P is absorbed by the cooling roller 22B and sufficiently cooled.

  In the cooling effect evaluation experiment conducted by the present applicants, the cooling roller has a double-pipe structure, and when the surface temperature of the paper P immediately after passing through the heat fixing means 16 is about 100 ° C., it passes through the cooling device 18B. By doing so, the paper P could be cooled to about 55 ° C. by actual measurement. That is, it was confirmed that the cooling effect was further improved by about 5 ° C. by changing the cooling roller from a single tube structure to a double tube structure.

  As will be described later, the cooling device 18B communicates / connects with a coolant circulation means such as a radiator 24 equipped with a tank 26, a pump 25, and a cooling fan 23 via a rotary pipe joint means, and the enclosed coolant is circulated. The cooling roller 22B is cooled.

  FIG. 2 is a schematic cross-sectional view (XX cross-sectional view of FIG. 1) of the cooling roller 22B of the present invention in which a double-type rotary joint 35B as a rotary pipe joint means is attached to both ends. 3 and 4 are enlarged views of the left end portion and the right end portion thereof.

  As shown in the figure, the cooling roller 22B has a double tube structure comprising an outer tube and an inner tube, that is, an outer tube comprising a roller outer tube 22Ba and flanges 22d attached to both ends of the roller outer tube 22Ba, and an inner roller. The roller outer tube 22Ba rotates and conveys the paper P in contact with a hollow double tube structure composed of an inner tube made of the tube 22Bb. The roller outer tube 22Ba and the roller inner tube 22Bb together form a one-way flow path. That is, the cooling roller 22B having a double tube structure forms two separate unidirectional flow paths, thereby cooling the coolant flowing in the roller outer tube 22Ba with the coolant flowing in the roller inner tube 22Bb, and The cooling performance can be improved as compared with the cooling roller having the structure.

  In the present embodiment, the flow direction of the coolant flowing in the outer flow path between the roller outer tube 22Ba and the inner tube 22Bb and the flow direction of the coolant flowing in the inner flow path in the inner tube 22Bb are the cooling roller. Axial direction is opposite.

  Thus, since the flow direction of the cooling liquid flowing through the outer flow path and the flow direction of the cooling liquid flowing through the inner flow path are opposite to each other in the cooling roller axial direction, When flowing from the other side to the other end side, the coolant flows from the other end side to the one end side in the inner flow path. As a result, the cooling liquid in the outer flow path is cooled by the cooling liquid in the inner flow path whose temperature is lower toward the other end side where the temperature of the cooling liquid in the outer flow path becomes higher due to the heat absorbed by the cooling roller 22B from the paper. Can do. In addition, when the coolant flows from the other end side to the one end side in the outer channel, the coolant flows from the one end side to the other end side in the inner channel. As a result, the cooling liquid in the outer flow path can be cooled by the cooling liquid in the inner flow path having a lower temperature toward the one end side where the temperature of the cooling liquid in the outer flow path becomes higher due to the heat absorbed by the cooling roller 22B from the paper. it can. Therefore, the cooling roller axial direction of the cooling liquid flowing through the outer flow path is different from the conventional configuration in which the flow direction of the cooling liquid flowing through the outer flow path is the same as the flow direction of the cooling liquid flowing through the inner flow path. The temperature difference can be reduced. Accordingly, the temperature difference in the cooling roller axial direction on the surface of the cooling roller is reduced accordingly, so that the difference in cooling efficiency with respect to the sheet generated in the cooling roller axial direction can be reduced.

  The configuration of the cooling roller 22B will be described below. Since the left end portion and the right end portion of the cooling roller 22B have the same configuration, description will be made mainly using the left end portion. Therefore, the right end portion of FIG. 2 and the detailed instruction symbol of FIG. 4 are omitted.

  The roller outer tube 22Ba of the cooling roller 22B is configured at both ends by a flange 22d to which the bearing 22g is attached. The leakage preventing O-ring 22e is inserted into the flange 22d, and the flange 22d is attached to the roller outer tube 22Ba by a screw 22f. Yes. At this time, the flange 22d is inserted into and attached to the roller outer tube 22Ba in a fitting relationship, and is coaxial with the roller outer tube 22Ba. The cooling roller 22B is rotatably supported at both ends with respect to the bracket 34 of the cooling device 18B using the bearings 22g of the flanges 22d at both ends.

  Further, the flange 22d is formed with a coupling portion composed of a parallel screw portion 22h and a fitting portion 22i, and the flange 22d has a parallel screw portion 35Bb and a fitting portion 35Bc formed so as to face the coupling portion. A rotor 35Ba is attached. The parallel thread portions are threaded in such a direction as to be tightened with respect to the rotation direction of the roller outer tube 22Ba (the conveyance direction of the paper P). The rotor 35Ba is a component part of the rotary joint 35B and is rotatable. The attachment of the rotary joint 35B and the flange 22d is the insertion attachment by the fitting relationship as described above, and the coaxiality between the rotor 35Ba and the flange 22d is obtained. The rotor 35Ba is rotatably supported by the casing 35Be of the rotary joint 35B in a fitting relationship with two bearings 35d provided at intervals. From the above, the roller outer tube 22Ba is in a state in which the shaft is aligned with the casing 35Be of the rotary joint 35B through the rotor 35Ba and the flange 22d, which are attached in a fitting relationship, and high-precision rotation is achieved. It can be done. An O-ring 35g that prevents leakage from the flange 22d is inserted into the rotor 35Ba.

  Subsequently, although the configuration up to the above is common, the type of cooling roller is different depending on the method of supporting the roller inner tube 22Bb, which will be described. There are two types, Type 1 and Type 2, as follows, and the configuration of each will be described.

[Configuration example 1]
<Type 1 cooling roller>
The type 1 cooling roller is configured such that the roller outer tube 22Ba rotates and the roller inner tube 22Bb does not rotate.

  The type 1 cooling roller 22B will be described below. Since this type is the configuration of the cooling roller 22B shown in FIG. 2, description will be made mainly using the left end side of the cooling roller 22B. This type 1 cooling roller 22B is preferably used when it is desired to cause a turbulent flow in the unidirectional flow of the coolant flowing in the outer flow path between the roller outer tube 22Ba and the inner tube 22Bb.

  As shown in FIG. 2, one end side of the roller inner tube 22Bb is fixedly supported and the other end is fitted and supported so that the roller inner tube 22Bb does not rotate at the rotary joints 35B attached to both ends of the cooling roller 22b. Fixed support. Specifically, the roller inner pipe 22Bb is attached to the rotary joint 35B by, for example, fixing and supporting one rotary joint 35B by fitting and fitting into a flange 35f attached to the casing 35Be, and attaching to the other rotary joint 35B. Is supported by being fitted and inserted into the flange 35f, or fixed after the fitting is inserted. Since the casing 35Be, the flange 35f, and the roller inner tube 22Bb are inserted or press-fitted in a fitting relationship with each other, the coaxiality of the roller inner tube 22Bb is brought out of the casing 35Be. The flange 35f is fixed after inserting an O-ring 35i for preventing leakage into the casing 35Be with a screw 35h.

  With the above configuration, the coaxial degree of the roller outer tube 22Ba and the roller inner tube 22Bb is obtained at both ends of the cooling roller 22B with reference to the rotary joint 35B (casing 35Be), and with respect to the rotary joint 35B (casing 35Be). In the fitting relationship, the roller outer tube 22Ba is rotatably supported, and the roller inner tube 22Bb is supported so as not to rotate.

  The flow path of the coolant is indicated by arrows. The coolant of the medium A is supplied from the supply port of the rotary joint 35B on the lower side in the drawing that leads to the inside of the roller outer tube 22Ba, passes through the narrow gap between the roller inner tube 22Bb and the rotor 35Ba, and the roller outer tube 22Ba and the roller inner tube. A wide gap formed by the tube 22Bb flows in the axial direction to form a one-way flow path, and is discharged from the rotary joint 35B on the opposite side (upper side in the figure). Further, the coolant of the medium B is supplied from the upper rotary joint 35B in the drawing leading to the inside of the roller inner tube 22Bb, flows through the roller inner tube 22Bb to the rotary joint 35B on the opposite side (lower in the drawing), Another unidirectional flow path is formed and discharged. As described above, the cooling roller 22B having the double-pipe structure has the coolant flow direction and the inner flow path (roller) of the medium A flowing through the outer flow path (flow path between the roller outer pipe 22Ba and the roller inner pipe 22Bb). There are two unidirectional flow paths such that the flow direction of the coolant of the medium B flowing through the flow path in the inner pipe 22Bb is opposite to the cooling roller axial direction, and via the rotary joints 35B at both ends. A coolant circulation unit and a closed loop flow path are formed to circulate the coolants of the medium A and the medium B.

  The coolant of medium A and the coolant of medium B flow in the roller outer tube 22Ba and the roller inner tube 22Bb, respectively, thereby suppressing an increase in the surface temperature of the roller outer tube 22Ba. As a result, the cooling performance can be improved as a cooling roller. It is said.

  In addition, the cooling roller 22B can be attached and detached from components so as to be able to cope with reuse, recycling, and replacement of parts when trouble occurs.

  FIG. 5 shows a roller outer tube 22Ba, a roller inner tube 22Bb, a flange 22d, and a rotary joint 35B, which are main components of the cooling roller 22B, arranged in parts. This is also a state before the joint 35B is attached. In this figure, an O-ring 22e is incorporated in the flange 22d, but it is naturally possible to attach and remove it in parts. Since the rotary joint 35B can be attached to and detached from the cooling roller 22B, the rotary joint 35B can be replaced.

  The cooling roller 22B is configured so that it can be easily assembled and disassembled (attachment / detachment of components), and will be described following the assembly procedure. At the same time, the mounting procedure to the cooling device 18B will be described (see the procedure arrow numbers in the figure).

  First, one end side of the roller inner tube 22Bb is fitted into the flange 35f removed from the casing 35Be of the rotary joint 35B and fixedly supported (procedure (1)). Next, the flange 22d is fitted and inserted into the roller outer tube 22Ba and fixed with a screw 22f (not shown) (procedure (2)). Then, the bearing 22g is fitted and inserted into the flange 22d so as to be slidable in the axial direction (step (3)). Note that the work procedure of the procedure (1) and the procedure (2) may be reversed.

FIG. 6 shows a state after the procedures (1), (2), and (3).
After the procedure (3), first, a C-type retaining ring 35L for determining the position of the bearing 22g is inserted into the rotor 35Ba of the rotary joint 35B in a later step (the C-type retaining ring 35L may be placed on the flange 22d side). Then, the flange 22d of the roller outer tube 22Ba is fitted and inserted into the rotor 35Ba (fitted with the fitting portion 22i and the fitting portion 35Bc), and the parallel screw portion (screw fastening with the parallel screw portion 22h and the parallel screw portion 35Bb) is performed. Fix (Procedure (4)). Thereafter, the roller inner tube 22Bb with the flange 35f is inserted from the rear end opening of the lower casing 35Be in the drawing, and the inside of the lower rotor 35Ba, the roller outer tube 22Ba and the upper rotor 35Ba in the drawing is inserted. Pass through. Then, after passing through the roller inner tube 22Bb until the flange 35f hits the rear end surface of the lower casing 35Be in the drawing, the flange 35f is fitted and fixed to the casing (body portion) 35Be with a screw 35h (not shown) (procedure ( 5)). Finally, a flange 35f is fitted and inserted into the rear end opening of the casing 35Be of the upper rotary joint 35B in the drawing, and fixed with a screw 35h (not shown) (procedure (6)). At this time, the upper end of the roller inner tube 22Bb is fitted and inserted into the flange 35f to be supported or fixed. Thus, the assembly of the cooling roller 22B and the attachment of the rotary joint 35B are completed, as shown in FIG. The disassembly of the cooling roller 22B, the rotary joint 35B, and the like may be performed by reversing the above procedure, so that the components of the cooling roller 22B can be attached and detached and the rotary joint 35B can be attached and removed in units.

  As shown in FIG. 7, the cooling roller 22B having the rotary joint 35B attached to both ends is mounted on the cooling device 18B. The cooling roller 22B is inserted into the notch opening 34a (see FIG. 1) opened in the bracket 34 of the cooling device 18B. Insert to the set position (Procedure (7)). Then, the bearing 22g located outside the bracket 34 is slid until it hits the bracket 34 (procedure (8)). Finally, the C-type retaining ring 35L is positioned so that the bearing 22g does not come off (procedure (9)). Thus, the mounting of the cooling roller 22B to the cooling device 18B is completed, and the state shown in FIG. 2 is obtained, and the cooling roller 22B is supported at both ends by the bracket 34 and can freely rotate.

  As described above, the cooling roller 22B can be attached to and detached from the rotor 35Ba and the flange 22d, the roller outer tube 22Ba and the flange 22d, the roller inner tube 22Bb and the flange 35f, and the casing 35Be and the flange 35f only by the screw fastening method. Doing so will cause axis misalignment. In order to make the cooling roller 22B with high rotational accuracy, the fitting portion must be provided with a fitting / fitting portion for axial alignment as in this configuration example.

[Configuration example 2]
<Type 2 cooling roller>
The type 2 cooling roller is configured such that the roller outer tube 22Ba rotates and the roller inner tube 22Bb also rotates together with the roller outer tube 22Ba.

  The type 2 cooling roller 22B will be described below with reference to FIG. 8 and FIGS. 9 and 10 which are enlarged views of the left end portion and the right end portion thereof. Therefore, the right end part of FIG. 8 and the detailed instruction symbol of FIG. 10 are omitted. This type 2 cooling roller 22B is used to smooth the unidirectional flow (flow in the axial direction and rotational direction) of the coolant flowing in the outer flow path between the roller outer tube 22Ba and the inner tube 22Bb. Is preferred.

  The concept of aligning the shafts by the support method based on the fitting relationship is the same as that of the type 1 cooling roller. The difference from the type 1 cooling roller is that, as shown in FIG. 8, both ends of the roller inner tube 22Bb are attached to the flange 35Bf of the casing 35Be of the rotary joint 35B via bearings 35k so that the roller inner tube 22Bb rotates. Support for rotation. Then, the roller inner tube 22Ba and the roller inner tube 22Bb are also rotatably supported with respect to the rotary joint 35B (casing 35Be) at both ends. The roller inner tube 22Bb is rotated along with the rotation force of the roller outer tube 22Ba transmitted to the roller inner tube 22Bb by, for example, an engaging means. As shown in the YY cross-sectional view of FIG. 9, the follow-up method uses, for example, an engagement means including an engagement pin 22p of the roller inner tube 22Bb and an engagement groove 22m of the roller outer tube 22Ba. When the engaging pin 22p is hooked on 22m, the roller inner tube 22Bb rotates with it. Note that the flow path of the coolant for the medium A and the coolant for the medium B flowing in one direction in the cooling roller 22B is the same as that of the type 1, and thus the description thereof is omitted.

  In addition, the type 2 cooling roller 22B can be attached to and detached from the components and the rotary joint 35B.

  FIGS. 11 to 13 show the procedure from assembling the cooling roller 22B to the mounting procedure of the cooling roller 22B to the cooling device 18B (see the procedure arrow numbers in the figure).

  First, as shown in FIG. 11, the flange 35Bf having the bearing 35k fixed therein is fitted and inserted only into the casing 35Be of the rotary joint 35B on one side (for example, the lower side in the figure) and fixed with screws 35h (not shown). (Procedure (1)). Next, the flange 22d is fitted and inserted into the rotor 35Ba of both rotary joints 35B to which the C-type retaining ring 35L has been temporarily inserted while being passed through the bearing 22g (procedure (2)).

  FIG. 12 shows a state after the procedures (1) and (2). After the procedure (2), the roller inner tube 22Bb is inserted into the lower rotary joint 35B in the figure, and the tip is fitted and inserted into the bearing 35k of the flange 35Bf (procedure (3)). Next, the other rotary joint 35B is attached and fixed to the roller outer tube 22Ba in a fitting relationship with the flange 22d (procedure (4)), and the roller outer tube 22Ba is attached to the roller inner tube 22Bb so as to cover the roller inner tube 22Bb. Assemble from the free end side. When the free end passes through the upper rotary joint 35B in the drawing, the lower rotary joint 35B and the roller outer tube 22Ba in the drawing are attached and fixed in a fitting relationship via the flange 22d (procedure (5)). As the engaging means so that the roller inner tube 22Bb rotates with the roller outer tube 22Ba, the engagement pin 22p is provided on the roller inner tube 22Bb side and the engagement groove 22m is provided on the roller outer tube 22Ba side. When assembling the roller outer tube 22Ba so as to cover the tube 22Bb, the engagement pin 22p is fitted into the engagement groove 22m so that the following relationship is established. Refer to the YY cross-sectional view in FIG. Finally, the free end side (upper end side in the figure) of the roller inner tube 22Bb is fitted and inserted into the bearing 35k of the upper flange 35Bf in the figure, and at the same time, the flange 35Bf is inserted into the casing of the rotary joint 35B. It is fitted and inserted into 35Be and fixed with a screw 35h (not shown) (procedure (6)). The assembly of the type 2 cooling roller 22B and the attachment of the rotary joint 35B are completed as shown in FIG. The disassembly of the cooling roller 22B, the rotary joint 35, and the like may be performed by reversing the above procedure, so that the components of the cooling roller 22B can be attached and detached and the rotary joint 35B can be attached and removed in units of parts.

  The procedure for mounting the cooling roller 22B with the rotary joint 35B attached to both ends to the cooling device 18B is the same as that described with reference to FIG.

  As described above, in the cooling roller 22B, the fastening method such as the rotor 35Ba and the flange 22d, the roller outer tube 22Ba and the flange 22d, and the casing 35Be and the flange 35f is only screwed, or the roller inner tube 22Bb and the bearing 35k are rotated. If the fitting of the parts is made rough, each axis will be displaced. In order to make the cooling roller 22B with high rotational accuracy, as in this embodiment, the fastening portion must be fitted with a fitting fitting portion for axial alignment, and the rotating portion can be securely supported at both ends. It is necessary to increase the alignment accuracy. Also in this type of cooling roller 22B, the flow direction of the coolant (medium A) flowing through the outer flow path (flow path between the roller outer pipe 22Ba and the roller inner pipe 22Bb) and the inner flow path (inside the roller inner pipe 22Bb). The flow direction of the coolant (medium B) flowing in the flow path) is opposite to the direction of the cooling roller axis, so that the heat of the cooling roller 22B from the paper P absorbs heat of the coolant (medium A) in the outer flow path. The cooling liquid in the outer flow path can be cooled by the cooling liquid (medium B) in the inner flow path whose temperature is lower at the downstream side where the temperature is higher. As a result, the temperature difference in the cooling roller axial direction on the surface of the cooling roller is reduced, so that the difference in cooling efficiency with respect to the paper P generated in the cooling roller axial direction can be reduced.

  Also, in the cooling roller 22B having a double tube structure, the cooling efficiency can be improved by providing a stirring means in the gap formed by the roller outer tube 22Ba and the roller inner tube 22Bb.

[Configuration example 3]
FIG. 14 is a schematic cross-sectional view of the cooling roller 22B and the like when a coil spring 22w as a stirring unit is attached in close contact with the inner wall of the roller outer tube 22Ba of the type 1 cooling roller 22B shown in the configuration example 1. The coil spring 22w rotates with the rotation of the roller outer tube 22Ba. By rotating the coil spring 22w, the cooling liquid (medium A) is fed in the rotation direction and the axial direction while stirring, and the cooling performance of the roller outer tube 22Ba is improved. Similarly, in the type 2 cooling roller 22 shown in the configuration example 2, the coil spring 22w as the stirring means is attached in close contact with the inner wall of the roller outer tube 22Ba so that the outside of the roller can be removed for the same reason as described above. The cooling performance of the tube 22Ba can be improved.

  Next, FIGS. 15, 16, and 17 show a coolant circulation system in the cooling roller 22B in which individual flow paths are formed in the roller outer tube 22Ba and the roller inner tube 22Bb by a double tube structure. In each of the drawings, the type 1 cooling roller 22B is used, but the circulation system is the same even when the type 2 cooling roller 2B is used.

Further, this type of cooling roller 22B includes a flow direction of the coolant (medium A) flowing through the outer flow path (flow path between the roller outer pipe 22Ba and the roller inner pipe 22Bb) and an inner flow path (roller inner pipe 22Bb). The flow direction of the cooling liquid (medium B) flowing through the inner flow path) is opposite to the cooling roller axial direction, so that the cooling liquid (medium A) in the outer flow path is absorbed by the heat absorbed by the cooling roller 22B from the paper P. The cooling liquid (medium A) in the outer flow path can be cooled by the cooling liquid (medium B) in the inner flow path, which has a lower temperature, on the downstream side where the temperature becomes higher. As a result, the temperature difference in the cooling roller axial direction on the surface of the cooling roller is reduced, so that the difference in cooling efficiency with respect to the paper P generated in the cooling roller axial direction can be reduced.
As a cooling liquid circulation system, the cooling roller 22B having two one-way flow paths and the cooling liquid circulation means form a closed loop flow path to circulate the cooling liquid. However, the coolant circulation means is shared or individually used in each flow path of the roller outer tube 22Ba and the roller inner tube 22Bb, or the coolant flowing through the roller outer tube 22Ba and the roller inner tube 22Bb is the same or different. The circulation system differs depending on whether the liquid is used. Therefore, these will be described with reference to FIGS. 15, 16, and 17.

  FIG. 15 shares the coolant circulation means for flowing the coolant to the outer flow path between the roller outer tube 22Ba and the inner tube 22Bb and the inner flow channel in the inner tube, and the outer flow channel and the inner flow channel. Fig. 6 schematically shows a circulation system when the same coolant is supplied to each other. In this way, the cooling liquid supplied to the outer flow path and the inner flow path is made the same cooling liquid (medium A), so that the cooling liquid circulating means is shared, and a single closed loop flow path is sufficient.

  In the circulation process of the coolant (medium A), in the roller outer tube 22Ba, the heat received on the surface of the rotating roller outer tube 22Ba is transferred to the inside, so that the coolant (medium A) in the roller outer tube 22Ba is transferred to the inside. The heated coolant (medium A) is discharged from one (upper side in the figure) rotary joint 35B, and the tank 26, the pump 25, and the radiator 24 (including the cooling fan 23), which are coolant circulation means, are discharged. In the process, the temperature of the coolant (medium A) is lowered to near room temperature. Then, the coolant (medium A) is supplied again from the other (lower side in the drawing) rotary joint 35B to the roller outer tube 22Ba. In the roller inner tube 22Bb, the temperature of the coolant (medium A) in the roller outer tube 22Ba is received by the heated coolant (medium A) in the roller outer tube 22Ba on the surface of the roller inner tube 22Bb. Lower. The coolant (medium A) in the roller inner tube 22Bb warmed by receiving heat is discharged from the other rotary joint 35B (lower side in the figure). Thereafter, the coolant (medium A) having a lowered temperature is supplied again from one (upper side in the figure) to the roller inner tube 22Bb through the coolant circulation means shared with the roller outer tube 22Ba.

  According to the exhaust heat cycle of the two flow paths sharing the cooling liquid circulation means, the cooling liquid of the outer flow path not only in the radiator 24 but also in the roller outer pipe 22Ba due to the heat receiving effect of the roller inner pipe 22Bb. Since the temperature of (medium A) can be lowered, that is, an increase in the surface temperature of the roller outer tube 22Ba can be suppressed, the cooling efficiency can be improved as compared with the single tube structure. Further, according to this configuration, the cooling efficiency can be improved and the cooling liquid circulation means can be shared and the same cooling liquid can be used, so that the space can be saved at low cost as the cooling liquid circulation system.

  FIG. 16 individually has a coolant circulation means for flowing a coolant through the outer flow path between the roller outer pipe 22Ba and the inner pipe 22Bb and the inner flow path inside the inner pipe. 1 schematically shows a circulation system in the case where the same coolant flows through a flow path.

  For example, the coolant of the medium B flowing in the roller inner tube 22Bb described in the figure is the medium A, the coolant of the same medium A as the roller outer tube 22Ba is flowed, and the coolant circulating means is individually provided. Even if the same cooling medium is used, unlike the circulation system shown in FIG. 15, two closed loop flow paths are formed.

  In the circulation process of the coolant (medium A) in each of the roller outer tube 22Ba and the roller inner tube 22Bb, the same coolant (medium A) flows through the individual coolant circulating means. It is the same circulation process as the circulation system.

  In the case of the circulation system shown in FIG. 15, the coolant (medium A) has a large temperature difference (the temperature of the coolant discharged from the roller outer tube 22Ba) at the time of being discharged from the roller outer tube 22Ba and the roller inner tube 22Bb. However, since it passes through the same coolant circulating means, it is at the same temperature when it is supplied again to the roller outer tube 22Ba and the roller inner tube 22Bb. However, in order to mix the discharged cooling liquid (medium A) in the tank 26 and lower the increased liquid temperature to near room temperature, considerable cooling power of the radiator 24 and the cooling fan 23 is required. In order to obtain a cooling roller 22B with higher cooling efficiency, it is effective to individually control the flow rate and temperature of the cooling liquid (medium A) in the outer flow path and the inner flow path, as shown in FIG. It is not possible to cope with this in a circulating system.

  On the other hand, in the circulation system shown in FIG. 16, the cooling power of the radiators 24a and 24b and the cooling fans 23a and 23b is small, and the coolant (medium A) is not mixed. By individually setting the cooling performance of the fan, the cooling liquid (medium A) temperature discharged from the roller outer tube 22Ba and the roller inner tube 22Bb is set to a desired temperature at the time of supply again. Can do. In addition, since the cooling fluid circulating means is individually provided, the rotational speeds of the pumps 25a and 25b and the cooling fans 23a and 23b can be controlled, respectively, so that the cooling fluid (medium) in the roller outer tube 22Ba and the roller inner tube 22Bb can be controlled. The flow rate and temperature of A) can be set to desired values.

  As described above, the cooling performance can be controlled by taking appropriate measures individually in each flow path. Further, according to this configuration, the cooling performance is improved and the same cooling liquid is used even if the cooling liquid circulation means is individually provided. Therefore, there is no work mistake such as mixing the cooling liquid when filling or refilling the cooling liquid. . Also, since only one type of coolant is sufficient, it is easy to store and manage.

  Further, in the circulation system shown in FIG. 16, different cooling liquids may be supplied to the outer flow path between the roller outer pipe 22Ba and the inner pipe 22Bb and the inner flow path in the inner pipe.

  That is, separate cooling liquid circulation means are provided to form two closed loop flow paths, and different cooling liquids such as medium A are passed through the roller outer tube 22Ba and medium B is passed through the roller inner tube 22Bb. The circulation process of the coolant (medium A) and the coolant (medium B) in each of the roller outer tube 22Ba and the roller inner tube 22Bb is the same as the circulation system shown in FIG. In this configuration, not only can the individual setting and control of the cooling liquid circulating means described above be possible, but also the cooling medium can be used with optimal characteristics, and combinations thereof can be set in various ways. Therefore, the cooling efficiency can be further improved. According to this configuration, the cooling performance is much better than the circulation system shown in FIG. 15 or the circulation system in the case where the same coolant is passed through the outer flow path and the inner flow path shown in FIG. It can be said that this is a circulation system that should be applied to a device that gives first priority.

  In FIG. 17, the tank is shared by the outer flow path between the roller outer pipe 22Ba and the inner pipe 22Bb and the inner flow path in the inner pipe, and other cooling liquid circulation means is divided between the outer flow path and the inner flow path. FIG. 2 schematically shows a circulation system that is individually provided and flows the same coolant through the outer channel and the inner channel.

  As shown in the figure, the tank 26 is shared between the outer flow path and the inner flow path, and the cooling liquid supplied to the outer flow path and the inner flow path is the same cooling liquid (medium A). Cooling liquid circulation means such as 25a and 25b and radiators 24a and 24b (including cooling fans 23a and 23b) are provided separately for the outer flow path and the inner flow path, and form two closed loop flow paths other than the tank. That is, it is the same as the circulation system shown in FIG. 16 except that the tank 26 is shared, and the circulation process of the coolant (medium A) is also performed for each of the rollers discharged from the roller outer tube 22Ba and the roller inner tube 22Bb. The circulating fluid (medium A) is the same as the circulation system shown in FIG. 16 except that the coolant (medium A) is once mixed in the tank 26 and then passed through the individual pumps 25a and 25b. According to this configuration, while having the advantage of the circulation system shown in FIG. 16, the tank 26 is shared, so that the space can be saved as compared with the circulation system shown in FIG. 16.

  In this embodiment, a liquid is used as the cooling medium. However, the present invention is not limited to this, and the present invention can be applied to a gas such as air or gas as the cooling medium. In this case, one of the medium flowing through the roller outer tube 22Ba and the roller inner tube 22Bb may be liquid and the other may be gas, and the cooling effect can be further improved.

  18 and 19 are schematic structural views of a tandem type intermediate transfer belt type color image forming apparatus equipped with a cooling roller 22B having a double-pipe structure and a cooling device 18B having a cooling liquid circulation system of the present invention. The image forming apparatus provided with the cooling device 18B of the present invention is used for an application in which a recording medium such as a sheet is continuously passed through the image forming process (printing process) for a long time (for example, several days) as in the printing process. It is a high-speed machine that can perform image formation processing of about 100 to 120 sheets per minute with A4 paper. The present invention can be similarly applied to image forming apparatuses other than such high-speed machines (for example, electrophotographic image forming apparatuses such as copying machines and printers used in ordinary offices).

  18 shows a color image forming apparatus when the cooling liquid circulation system shown in FIG. 15 is adopted, and FIG. 19 shows a color image forming apparatus when the cooling liquid circulation system shown in FIG. 16 is adopted.

  The color image forming apparatus of the coolant circulation system shown in FIG. 15 will be described with reference to FIG. The color image forming apparatus shown in FIG. 19 is the same as the color image forming apparatus shown in FIG. 18 except for the configuration and operational effects of the coolant circulation system shown in FIG.

  An intermediate transfer belt 1 as an intermediate transfer medium is stretched by a plurality of rollers, the intermediate transfer belt 1 is configured to rotate by these rollers, and a process unit for image formation is disposed around the intermediate transfer belt 1. ing.

  When the rotation direction of the intermediate transfer belt 1 is indicated by an arrow “a”, image formation is performed in order from the upstream side in the rotation direction of the intermediate transfer belt 1 between the rollers 2 and 3 above the intermediate transfer belt 1. As the process means, a first image station 4Y, a second image station 4C, a third image station 4M, and a fifth image station 4Bk are arranged. For example, the first image station 4Y includes a charging unit 10, an optical writing unit 12, a developing device 13, and a cleaning unit 14 arranged around a drum-shaped photoconductor 11, and is further exposed to light with the intermediate transfer belt 1 interposed therebetween. A primary transfer roller 15 as a transfer means to the intermediate transfer belt 1 is provided at a position opposed to the body 11, and the other three image stations have the same configuration. These four image stations are arranged side by side so as to have a predetermined pitch interval.

  In FIG. 18, the optical writing unit 12 is an optical system using an LED as a light source. However, the optical writing unit 12 may be configured by a laser optical system using a semiconductor laser as a light source, and exposes the photoconductor 11 according to image information.

  Below the intermediate transfer belt 1 is a sheet storage unit 19 for recording paper P, a paper feed roller 20, a pair of registration rollers 21, and a transfer means for paper P provided to face the roller 5. In the next transfer roller 6, the cleaning means 9 provided at the position facing the roller 8, the heat fixing means 16, the cooling device 18 </ b> B having the cooling roller 22 </ b> B of the present invention for cooling the paper P, and the paper P discharging section after toner fixing. A certain paper discharge accommodating portion 17 and the like are arranged. A paper transport path 28 extending from the paper storage unit 19 to the paper discharge storage unit 17 extends. In order to form an image on the back side when forming a double-sided image, a paper conveyance path 29 for double-sided image formation is also provided which reverses the paper P that has once passed through the cooling device 18 and conveys it again to the pair of registration rollers 21.

  The cooling roller 22B of the cooling device 18B is a heat receiving portion that receives the heat of the paper P, and is connected and connected by a pipe 27 together with a radiator 24, a pump 25, and a tank 26 equipped with a cooling fan 23, as shown in FIG. A cooling liquid circulation system is formed, and the cooling liquid is enclosed.

  As shown by the arrow of the pipe 27, the circulation path of the cooling liquid branches the cooling liquid cooled by the radiator 24 on the way, and sends it to two places of the roller outer pipe 22Ba and the roller inner pipe 22Bb of the cooling roller 22B. The roller outer tube 22Ba and the roller inner tube 22Bb are passed through the inside and then discharged, then sent to the tank 26 and the pump 25, and then returned to the radiator 24. The coolant is circulated by the rotational pressure of the pump 25. The radiator 24 radiates heat to cool the cooling liquid, that is, the cooling roller 22B. The power of the pump 25, the size of the radiator 24, and the like are selected based on the flow rate, pressure, cooling efficiency, and the like determined by the thermal design conditions (the amount of heat and temperature conditions that the cooling roller 22B should cool).

  If attention is paid to the first image station 4Y, the image forming process is in accordance with a general electrostatic recording system, and the light writing means 12 is applied onto the photoreceptor 11 uniformly charged by the charging means 10 in the dark. The electrostatic latent image is formed by exposure, and the electrostatic latent image is visualized as a toner image by the developing device 13. The toner image is transferred to the intermediate transfer belt 1 by the primary transfer roller 15. After the transfer, the photoconductor 11 is cleaned by the cleaning means 14. The other image stations have the same configuration as the first image station 4Y, and the same image forming process is performed.

  Each developing device 13 in each of the image stations 4Y, 4C, 4M, and 4Bk has a visible image forming function using toners of four different colors. Yellow (Y) and yellow (Y) in each of the image stations 4Y, 4C, 4M, and 4Bk A full color image can be formed by sharing cyan (C), magenta (M), and black (Bk). Therefore, while the same image forming area of the intermediate transfer belt 1 sequentially passes through the four image stations 4Y, 4C, 4M, and 4Bk, the primary images provided so as to face the respective photoreceptors 11 with the intermediate transfer belt 1 interposed therebetween. If the toner images are transferred one by one on the intermediate transfer belt 1 by the transfer bias applied by the transfer roller 15, the same image forming area will be assigned to each of the image stations 4Y, 4C, 4M, and 4Bk. At the time of passing, the full color toner image can be obtained by overlapping transfer on the same image area.

  Then, the full-color toner image formed on the intermediate transfer belt 1 is transferred to a sheet P as a sheet-like medium. The intermediate transfer belt 1 after the transfer is cleaned by a cleaning unit 9. For transfer onto the paper P, a transfer bias is applied to the secondary transfer roller 6 via the intermediate transfer belt 1 on the roller 5 at the time of transfer, and the paper P is applied to the nip portion between the secondary transfer roller 6 and the intermediate transfer belt 1. This is done by passing. After the transfer onto the paper P, the full-color toner image carried on the transfer paper P is fixed by the thermal fixing means 16, so that a full-color final image is formed on the paper P and is discharged to the paper discharge container 17 and stacked. Is done.

  In the color image forming apparatus of the present embodiment, the paper P passes through the cooling device 18 </ b> B disposed immediately after the thermal fixing unit 16 before the paper P is discharged and stacked in the paper discharge storage unit 17. When passing, the paper P heated by the heat fixing means 16 passes while contacting the cooling roller 22B which is a heat receiving portion. Therefore, the surface of the cooling roller 22B absorbs heat from the paper P, and this heat is absorbed. This is transmitted to the cooling liquid inside the cooling roller 22B. Thereafter, the heated and heated cooling liquid is discharged from the cooling roller 22B, and is sent to the radiator 24 equipped with the cooling fan 23 through the tank 26 and the pump 25, where the heat is discharged outside the image forming apparatus. Be heated. The coolant whose heat is removed by the radiator 24 and lowered to near room temperature is then sent again to the cooling roller 22B. The sheet P heated to a high temperature by the heat fixing means 16 is efficiently cooled by the exhaust heat cycle having a high cooling performance by the cooling liquid medium. Therefore, the toner on the paper P can be surely cured when the paper P is discharged and stacked in the paper discharge container 17. In particular, it is possible to avoid the blocking phenomenon that has been a serious problem in the double-sided image formation output. Moreover, the cooling with the cooling liquid can contribute to the downsizing of the image forming apparatus because it is highly efficient and requires local cooling without requiring a large space as in the case of using a conventional fan or the like. . Therefore, when the high-speed image forming process of 100 sheets or more with A4 paper is continuously performed for a long time (for example, several days) as in the image forming apparatus of this embodiment, the surface temperature gradient in the axial direction of the cooling roller is set. Therefore, it is possible to reduce a problem such as a jam caused by curling of the paper, so that the image forming process can be continued without interruption.

  In addition, the outer roller tube 22Ba, the inner roller tube 22Bb, and the rotary joints 35B at both ends of the cooling roller 22B of the present invention are preferably fixed or rotatable in a fitting relationship with each other. By setting it in a fixed or rotatable state, the axes are reliably aligned with each other, and a highly accurate coaxiality can be realized. As a result, the eccentricity and vibration during rotation due to the shaft misalignment, which has been a problem in the past, are eliminated, the rotation accuracy and durability of the cooling roller 22B are improved, the risk of leakage due to eccentricity, vibration and breakage, and maintenance. And the frequency of parts replacement can be reduced. Further, if the rotation accuracy of the cooling roller 22B is improved, the paper P can be transported satisfactorily, so that a high-quality image can be obtained, and jamming and skew caused by poor rotation of the cooling roller 22B can be reduced. can do.

As described above, according to the present embodiment, the roller inner tube 22Bb is included in the outer tube including the roller outer tube 22Ba and the flanges 22d and 22f attached to both ends of the roller outer tube 22Ba, and the outer tube and the roller inner tube 22Bb. Is a double pipe structure having an outer flow path through which the cooling medium flows and an inner flow path through which the cooling medium flows in the roller inner tube 22Bb, and is rotatably supported by the housing of the apparatus main body via a bearing. The cooling roller 22B, the pump 25 serving as a cooling medium conveying means for conveying the cooling medium, and the cooling roller 22B are attached to both ends of the cooling roller 22B in a rotatable state, and the cooling roller 22B and the pump 25 are piped. And a rotary joint 35 that is two rotary pipe joints connected via a sheet member, and the sheet member is brought into contact with the cooling roller 22B. In the cooling device for cooling, the flow direction of the cooling medium conveyed to the outer flow path by the pump 25 in the outer flow path, and the cooling medium conveyed to the inner flow path by the pump 25 in the inner flow path The flow direction is opposite to the cooling roller axial direction. The flow direction of the cooling medium flowing through the outer flow path is opposite to the flow direction of the cooling medium flowing through the inner flow path in the axial direction of the cooling roller 22B. Thereby, the surface temperature gradient in the cooling roller 22B having a double tube structure can be reduced, and the cooling roller 22B having high cooling performance can be provided.
Further, according to the present embodiment, both ends of the outer tube are rotatably supported by the rotary joint 35, and both ends of the roller inner tube 22Bb are fixedly supported by the rotary joint 35, whereby the outer tube and the roller are supported. This is suitable for the case where it is desired to positively cause turbulent flow with respect to the flow of the coolant flowing in the gap formed by the inner pipe 22Bb (flow in the axial direction and the rotational direction). This is effective when the flow rate is low or when the flow velocity in the gap formed between the outer tube and the roller inner tube 22Bb is slow, and it is possible to improve the cooling efficiency by causing a turbulent flow in the coolant flow.
Further, according to the present embodiment, both ends of the outer tube and both ends of the roller inner tube 22Bb are rotatably supported by the rotary joint 35, whereby a gap formed between the outer tube and the roller inner tube 22Bb. This is suitable when the flow of the coolant flowing in the direction (flow in the axial direction and the rotational direction) is to be smooth, and particularly in the gap formed by the outer tube and the roller inner tube 22Bb with a large supply flow rate of the coolant. This is effective when the flow rate is fast, and it is possible to improve the cooling efficiency by smoothing the flow of the coolant.
Moreover, according to this embodiment, a cooling medium is conveyed by the pump 25 common to an outer side flow path and an inner side flow path, and thereby cost reduction and space saving can be achieved.
In addition, according to the present embodiment, the cooling medium 22 is conveyed to the outer flow path and the inner flow path by the individual pumps 25, thereby providing the cooling roller 22B with higher cooling performance by individual cooling control. it can.
Further, according to the present embodiment, the same cooling medium circulates in the outer channel and the inner channel, so that the cost can be reduced. Further, it is possible to reduce work space saving of the coolant circulation system, storage of the cooling medium, replenishment of the cooling medium, and the like.
In addition, according to the present embodiment, different cooling media circulate in the outer flow channel and the inner flow channel, thereby providing the cooling roller 22B with extremely good cooling performance by individual optimum selection of the cooling media. it can.
Further, according to the present embodiment, the coil spring 22w, which is a cooling medium stirring means for stirring the cooling medium, is provided between the outer tube and the roller inner tube 22Bb, so that the outer tube and the roller inner tube 22Bb It becomes possible to improve the cooling efficiency by actively disturbing the flow of the cooling liquid flowing in the formed gap.
Further, according to the present embodiment, the cooling medium agitating means for agitating the cooling medium is provided in the roller inner tube 22Bb, so that the flow of the coolant flowing in the roller inner tube 22Bb is actively disturbed and cooled. Efficiency can be improved.
Further, according to the present embodiment, the outer tube is attached so that both ends thereof are coaxially and rotatably fitted to the fitting portion 35Bc which is the first fitting portion of the rotary joint 35. Both ends of the tube 22Bb are coaxially fitted to a bearing 35k which is a second fitting portion of the rotary joint 35, and are supported in a rotatable or fixed state. Thereby, since each of the outer tube, the roller inner tube 22Bb, and the rotary joint 35 is attached to each other in a fitting relationship that can suppress backlash rather than screw fastening, the outer tube, the roller inner tube 22Bb, and the rotary joint 35 are attached to each other. The axial displacement between the three members of the joint 35 can be made smaller than when the screws are fastened. Accordingly, the vibration of the rotary joint 35 caused by the eccentricity when the outer tube is rotated can be reduced as compared with the case where the screw is fastened, because the shaft misalignment between the three parties is reduced.
In addition, according to the present embodiment, a toner image forming unit that forms a toner image on the sheet P that is a sheet-like member, and a thermal fixing unit that fixes the toner image formed on the sheet P to the sheet P by at least heat. And a cooling means for cooling the paper P on which the toner image is fixed by the heat fixing means, the cooling device of the present invention is used as the cooling means, which is much higher than the conventional one. Since the cooling device 18 having the cooling roller 22 having both the cooling performance and the high rotation accuracy is mounted on the image forming apparatus, it is possible to improve the paper cooling effect and the paper conveyance accuracy, and further to save the space. A forming apparatus can be provided.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 2 Roller 3 Roller 4 Image station 5 Roller 6 Secondary transfer roller 8 Roller 9 Cleaning means 10 Charging means 11 Photoconductor 12 Optical writing means 13 Developing device 14 Cleaning means 15 Primary transfer roller 16 Thermal fixing means 17 Paper discharge Storage unit 18 Cooling device 18A Cooling device 18B Cooling device 19 Paper storage unit 20 Paper feed roller 21 Registration roller pair 22A Cooling roller 22B Cooling roller 22Ba Roller outer tube 22Bb Roller inner tube 22 Cooling roller 22d Flange 22e Ring 22f Screw 22g Bearing 22h Parallel Screw portion 22i Fitting portion 22m Engaging groove 22p Engaging pin 22w Coil spring 23 Cooling fan 23a Cooling fan 24 Radiator 24a Radiator 25 Pump 25a Pump 26 Tank 27 Piping 28 Sheet conveying passage 29 sheet conveying path 34 bracket 34a opening 35 rotary joint 35A rotary joint 35B rotary joint 35Ba rotor 35Bb parallel screw portion 35Bc fitting portion 35Bf flange 35L wheel 35d bearing 35k bearing 35f flange 35g ring 35h screws 35i ring
122 Cooling roller 122a Outer tube 122b Inner tube

JP 2006-003819 A

Claims (11)

It is a double tube structure that includes an outer tube that encloses an inner tube in the outer tube, a cooling medium flows between the outer tube and the inner tube, and an inner tube channel that flows in the inner tube. A cooling roller rotatably supported on the housing of the apparatus main body via a bearing;
A cooling medium conveying means for conveying the cooling medium;
A rotating pipe joint unit that is attached to each of both ends of the cooling roller in a state where the cooling roller is rotatable, and connects the cooling roller and the cooling medium transport unit;
In the cooling device that cools the sheet-like member by bringing the sheet-like member into contact with the cooling roller,
The flow direction of the cooling medium conveyed to the outer flow path by the cooling medium conveying means in the outer flow path, and the cooling medium conveyed to the inner flow path by the cooling medium conveying means in the inner flow path A cooling device, wherein the flow direction is opposite to the cooling roller axial direction. The cooling device of claim 1.
Both ends of the outer pipe are rotatably supported by the rotary pipe joint means,
The cooling apparatus according to claim 1, wherein both ends of the inner pipe are fixedly supported by the rotary pipe joint means. The cooling device of claim 1.
The cooling apparatus according to claim 1, wherein both ends of the outer tube and both ends of the inner tube are rotatably supported by the rotary tube joint means. The cooling device according to claim 1, 2 or 3,
A cooling device, wherein the cooling medium is conveyed by the cooling medium conveying means common to the outer channel and the inner channel. The cooling device according to claim 1, 2 or 3,
A cooling device, wherein the cooling medium is transferred to the outer flow path and the inner flow path by the individual cooling medium transfer means. The cooling device according to claim 1, 2, 3, 4 or 5,
The cooling apparatus, wherein the same cooling medium circulates in the outer channel and the inner channel. The cooling device according to claim 1, 2, 3, 4 or 5,
A cooling device in which different cooling media circulate in the outer channel and the inner channel, respectively. The cooling device according to claim 1, 2, 3, 4, 5, 6 or 7,
A cooling device comprising a cooling medium stirring means for stirring the cooling medium between the outer tube and the inner tube. The cooling device according to claim 1, 2, 3, 4, 5, 6, 7 or 8.
A cooling apparatus comprising a cooling medium stirring means for stirring the cooling medium in the inner pipe. The cooling device according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9,
The outer pipe is attached so that both ends thereof are coaxially and rotatably fitted to the first fitting portion of the rotary pipe joint means,
The cooling apparatus according to claim 1, wherein both ends of the inner pipe are coaxially fitted to a second fitting portion of the rotary pipe joint means and supported in a rotatable or fixed state. Toner image forming means for forming a toner image on a sheet-like member;
Thermal fixing means for fixing the toner image formed on the sheet-like member to the sheet-like member at least by heat;
An image forming apparatus comprising: a cooling unit that cools the sheet-like member on which the toner image is fixed by the heat fixing unit;
An image forming apparatus using the cooling device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 as the cooling means.