JP5483174B2 - Cooling device and image forming apparatus - Google Patents

Description

  The present invention relates to a cooling device 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.] 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 thermal 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. In addition, the cooling roller has a tubular structure, and the cooling liquid flows into the cooling roller from one end side to the other end side in the longitudinal direction of the cooling roller. To be cooled.

  In recent years, there has been an increasing need for light printing such as high-speed printing such as telephone bills and receipts, and printing of color glossy images on cardboard, coated paper, and the like. In such a light printing, a large amount of printing is performed at a high speed, and thus it is necessary to cool a high-temperature sheet-like member in a shorter time. In addition, unlike office use, color printing is frequently performed and glossy images are often used. Therefore, high-efficiency cooling has come to be required in order to fix the image on the sheet-like member at a higher temperature in the fixing unit. .

  However, if the coolant is simply flowed into the cooling roller, the temperature of the coolant near the inner wall of the cooling roller becomes too high, and the cooling roller cannot be cooled effectively by the coolant. There may be a problem that the sheet cannot be properly cooled.

  The present invention has been made in view of the above problems, and an object thereof is to provide a cooling device and an image forming apparatus capable of improving the cooling efficiency of a sheet-like member by a cooling roller.

In order to achieve the above object, the invention of claim 1 comprises a cooling roller comprising a hollow tubular member, and a cooling medium conveying means for conveying a cooling liquid into the tubular member, and a sheet is provided on the cooling roller. In the cooling device for cooling the sheet-like member by contacting the sheet-like member, turbulent flow generating means for generating turbulent flow in the coolant is provided in the vicinity of the inner wall of the tubular member, and the turbulent flow generating means has a spiral shape The spiral winding direction is a winding direction in which feed in the direction opposite to the flow direction of the coolant flowing in the vicinity of the inner wall of the outer tube, which is the tubular member, is generated .
According to a second aspect of the invention, in the cooling device of the first aspect, the turbulent flow generating means is detachable from the tubular member.
The invention of claim 3 is the refrigeration apparatus according to claim 1 or 2, than the outer tube to the hollow interior of the upper Kigai tube enclosing the inner tube of the tubular structure, the outer tube and the inner tube A double-pipe structure having an outer flow path through which a cooling liquid flows and an inner flow path through which the cooling liquid flows in the inner pipe is characterized.
The invention of claim 4 is characterized in that, in the cooling device of claim 3, a cylinder having an outer diameter larger than that of the inner tube is attached inside the hollow of the outer tube so as to enclose the inner tube. To do.
According to a fifth aspect of the present invention, in the cooling device of the third aspect, the inner tube is rotatable at a different rotational speed in the same direction as the outer tube, and in a direction opposite to the rotation direction of the outer tube. It is provided in a rotatable or fixed state.
According to a sixth aspect of the present invention, in the cooling device of the fourth aspect, the cylinder can be rotated at a different rotational speed in the same direction as the rotation direction of the outer tube, and is rotated in a direction opposite to the rotation direction of the outer tube. It is possible or is provided in a fixed state.
The invention of claim 7 is the cooling device of claim 1, 2, 3, 4, 5 or 6, wherein the turbulent flow generating means is provided in a region where the sheet-like member extending in the longitudinal direction of the outer tube is sandwiched. It is characterized by being disposed.
Further, the invention of claim 8 is the cooling device of claim 1, 2, 3, 4, 5 or 6, wherein the turbulent flow generating means is provided in a region where the sheet-like member across the circumferential direction of the outer tube is sandwiched. It is characterized by being disposed.
The invention according to claim 9 is the cooling apparatus according to claim 1, 2, 3, 4, 5, 6, 7 or 8, further comprising a vibrating means for applying vibration to the turbulent flow generating means. Is.
The invention according to claim 10 is the cooling device according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein the turbulent flow generating means is a coil-shaped member. It is.
The invention according to claim 11 is the cooling device according to claim 1, wherein a core member is included in the hollow inside of the outer tube, and a gap formed between the outer tube provided with the turbulent flow generating means and the core member. It has a flow path through which a coolant flows.
The invention of claim 12 is characterized in that, in the cooling device of claim 11 , a second turbulent flow generating means for generating a turbulent flow in the coolant is provided in the vicinity of the outer peripheral surface of the core member. is there.
The invention of claim 13 is characterized in that, in the cooling device of claim 3, second turbulent flow generating means for generating turbulent flow in the coolant is provided in the vicinity of the outer peripheral surface of the inner tube. is there.
The invention of claim 14 is characterized in that, in the cooling device of claim 4, second turbulent flow generating means for generating turbulent flow in the coolant is provided in the vicinity of the outer peripheral surface of the cylinder. .
The invention of claim 15 is the cooling device of claim 11 , wherein the core member is rotatable at a different rotational speed in the same direction as the rotation direction of the outer tube, and is opposite to the rotation direction of the outer tube. It is provided in a rotatable or fixed state.
According to a sixteenth aspect of the present invention, there is provided 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 by at least 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, 8,9,10,11,12,13,1 4 or is characterized in the use of the cooling device 15.

  In the present invention, the flow of the coolant becomes turbulent near the inner wall of the tubular member by the turbulent flow generating means. Thereby, replacement of the coolant having a high temperature in the vicinity of the inner wall and the coolant having a low temperature at a position away from the inner wall is actively performed. Therefore, since the temperature of the coolant near the inner wall can be made lower than when no turbulent flow generating means is provided near the inner wall, the tubular member can be effectively cooled by the coolant. Therefore, the cooling efficiency of the sheet-like member by the cooling roller made of the tubular member can be improved.

  As mentioned above, according to this invention, there exists the outstanding effect that the cooling efficiency of the sheet-like member by a cooling roller can be improved.

(A) Sectional drawing at the time of cut | disconnecting the cooling roller which concerns on the structural example 1 in an axial direction. (B) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 1 in a diameter direction. Schematic of an example of the cooling device provided with the cooling roller of this invention which also plays the role of paper conveyance. Flow velocity distribution diagram inside the cooling roller. FIG. 6 is a heat transfer coefficient distribution diagram downstream of the peeling point on the inner wall surface of the cooling roller in the flow direction. (A) Enlarged sectional view of the cooling roller with the outer tube rotating clockwise and the coil-shaped member rotating clockwise. (B) Enlarged sectional view of the cooling roller with the outer tube rotating counterclockwise and the coiled member rotating clockwise. (C) Enlarged sectional view of the cooling roller with the outer tube rotating clockwise and the coil-shaped member rotating counterclockwise. (D) Enlarged sectional view of the cooling roller with the outer tube rotating counterclockwise and the coiled member rotating counterclockwise. The block diagram of the cooling roller which provided the net-like member as a turbulent flow generation means. Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 2 in an axial direction. (A) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 3 in an axial direction. (B) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 3 in a diameter direction. Explanatory drawing which showed an example in the case of providing a small diameter coil-shaped member in an outer tube | pipe. Explanatory drawing of the other example in the case of providing a small diameter coil-shaped member in an outer tube | pipe. The block diagram of a cooling roller at the time of arrange | positioning several small diameter coil-shaped members near the paper. The schematic diagram at the time of providing the vibration means which applies a vibration to a small diameter coil-shaped member. (A) The expanded sectional view of the cooling roller which consists of an outer tube | pipe and the core which provided the coil-shaped member in the inner wall vicinity. (B) The expanded sectional view of the cooling roller at the time of providing the coil-shaped member which is a turbulent flow generation means also in a core. (A) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 5 in an axial direction. (B) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 5 in a diameter direction. Sectional drawing at the time of cut | disconnecting the cooling roller in the diameter direction when the rotation speeds of an outer tube and an inner tube differ. Sectional drawing at the time of cut | disconnecting the cooling roller in an axial direction when the rotation speeds of an outer tube and an inner tube differ. (A) The expanded sectional view of the cooling roller of the pipe structure which consists of an outer pipe and an inner pipe. (B) The expanded sectional view of a cooling roller at the time of providing the coil-shaped member which is a turbulent flow generation means also in an inner pipe. Explanatory drawing which showed an example in the case of providing a small diameter coil-shaped member in an outer tube | pipe. Explanatory drawing of the other example in the case of providing a small diameter coil-shaped member in an outer tube | pipe. (A) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 6 in an axial direction. (B) Sectional drawing at the time of cut | disconnecting the cooling roller of the structural example 6 in a diameter direction. (A) The expanded sectional view of the cooling roller of the pipe structure which consists of an outer pipe, an inner pipe, and a cylinder. (B) The expanded sectional view of the cooling roller at the time of providing the coil-shaped member which is a turbulent flow generation means also in a cylinder. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment.

  A cooling roller and a cooling device according to an embodiment of the present invention will be described using an image forming apparatus in which toner on a recording sheet is fixed by a thermal 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.

  The cooling roller as the cooling means has a tubular structure, and the surface of the cooling roller is cooled by flowing and circulating a cooling liquid therein. A cooling device having this cooling roller is arranged in the paper transport path immediately after the heat fixing means, and the paper is transported by the cooling roller and simultaneously brought into contact with it to remove heat from the paper and cool it.

  FIG. 2 is a schematic diagram of an example of the cooling device 18 provided with the cooling roller 22 of the present invention that also functions as paper conveyance. The cooling device 18 is provided with rollers 40 and 41 arranged at intervals in the conveyance direction (left-right direction) of the sheet 20 that is a sheet-like member, and the conveyance belt 42 for conveying the sheet is extended. Then, using the roller 40 on the downstream side in the paper transport direction as a driving roller (connected to a drive source not shown), the transport belt 42 is rotated counterclockwise to transport the paper from the right side to the left side in the drawing.

  A heat fixing unit 16 is disposed upstream of the cooling device 18 in the paper conveyance direction, a paper discharge accommodating portion 17 is provided downstream of the cooling device 18 in the paper conveyance direction, and heat fixing is performed above the roller 41. An upper guide 43 that guides the paper 20 conveyed from the means 16 is provided. In addition, the cooling roller 22 is pressed from above at an intermediate position between the roller 40 and the roller 41 so as to bite into the conveying belt 42, and the cooling roller 22 rotates along with the conveying force of the conveying belt 42. It is like that. Reference numeral 34 in the drawing is a bracket that constitutes the main body of the cooling device 18, and is a member that supports components such as the roller 40, the roller 41, the cooling roller 22, and the upper guide 43 in a fixed or rotatable manner. The cooling device 18 is unitized by the bracket 44 and incorporated in the main body of the image forming apparatus.

  The paper 20 heated to the high temperature by the heat fixing unit 16 passes through the cooling device 18 before being discharged into the paper discharge accommodating portion 17. More specifically, the sheet 22 that has become hot through the heat fixing unit 16 enters between the upper guide 43 and the roller 41 of the cooling device 18, and then the nip formed by the cooling roller 22 and the conveying belt 42. The sheet passes through the area portion and is discharged to the paper discharge storage portion 17. The inside of the cooling roller 22 has a pipe structure, and the cooling liquid sufficiently cooled outside is supplied into the cooling roller 22 and circulated through the cooling roller 22, and then the cooling liquid is discharged from the cooling roller 22. Since the sheet 22 passes through the nip region formed by the contact between the cooling roller 22 and the conveying belt 42 while being in close contact with the cooling roller 22, the heat of the sheet 22 is absorbed by the cooling roller 22 at that time. The sheet 22 is sufficiently cooled. For example, by passing the paper 22 through the cooling device 18 when the surface temperature of the paper 22 immediately after passing through the heat fixing unit 16 is about 100 [° C.], the paper 22 is reduced to about 50 [° C.] to about 60 [° C.]. Can be cooled.

  As will be described later, the cooling roller 22 communicates / connects with a coolant circulating means such as the radiator 103 equipped with the tank 101, the pump 100, and the cooling fan 104 via the rotating pipe joint means, and the enclosed coolant is circulated. As a result, the cooling roller 22 is cooled.

  Here, in the electrophotographic image forming apparatus, the high-temperature paper on which the toner is fixed causes curling, and the toner is not completely solidified. Therefore, cooling is necessary to significantly deteriorate the image quality.

  Conventionally, in an electrophotographic image forming apparatus for office use, in order to cool high-temperature paper, a cooling fan can be used to cool the top surface and bottom surface of the paper by directly blowing air, or the paper can be terminated by a cooling fan. A number of methods have been adopted in which a sheet is sandwiched between heat pipe rollers that have been cooled and cooled.

  However, in recent years, electrophotographic image forming apparatuses have been increasingly demanded for light printing, such as high-speed printing such as telephone bills and receipts, and printing of color glossy images on cardboard and coated paper. It was. In light printing by such an electrophotographic image forming apparatus, a large amount of printing is performed at high speed, and thus it is necessary to cool a high-temperature paper in a shorter time. Also, unlike office use, color printing is more frequent and glossy images are more frequent. Therefore, the fixing unit fixes toner on paper at a higher temperature, so cooling that is more efficient than the conventional method is required. It was.

  Therefore, a liquid cooling method has started to be proposed in which circulating cooling liquid having higher cooling efficiency than the above-described cooling fan and heat pipe roller is passed through a hollow cooling roller, and the high-temperature paper is cooled by the cooling roller.

  In order to efficiently reduce the temperature of the sheet, it is necessary to increase the heat flux from the sheet to the cooling liquid across the wall of the cooling roller. Here, the heat flux between the wall portion of the cooling roller and the coolant is the number by convective heat transfer from "JP Hallman Heat Transfer Engineering <Top> (Brain Book Publishing), P11-12". It is expressed as 1.

ただし、
Ｗ［Ｗ］：熱流束
ｈ［Ｗ／ｍ^２・℃］：ローラ内壁面の熱伝達率
Ａ［ｍ^２］：ローラ内壁面積
Ｔｒ［℃］：ローラ内壁面温度
Ｔｗ［℃］：液温（ローラ内壁面より十分離れた位置で）

However,
W [W]: Heat flux h [W / m ² · ° C.]: Heat transfer coefficient A [m ² ] of roller inner wall surface: Roller inner wall area Tr [° C.] Roller inner wall surface temperature Tw [° C.]: Liquid temperature ( (In a position sufficiently away from the inner wall of the roller)

  From Equation 1, in order to increase the heat flux W, it is necessary to decrease the liquid temperature Tw, increase the roller inner wall area A, or improve the heat transfer coefficient h of the roller inner wall surface.

  In order to increase the heat flux W in Equation 1, the fluid flowing inside the roller is changed from air to cooling liquid to increase the thermal conductivity and specific heat, or to increase the fluid velocity inside the roller. This corresponds to increasing the heat transfer coefficient h of the wall surface. However, increasing the fluid velocity is not easy because it imposes a large burden on the pump for feeding the liquid into the roller.

  In addition, the heat flux W can be increased by lowering the liquid temperature Tw in Equation 1, but when a cooling fan and a radiator are used as means for lowering the liquid temperature Tw, the liquid temperature Tw is essential. Since the liquid temperature Tw cannot be lowered below room temperature, the liquid temperature Tw does not decrease as much as expected. Further, when a refrigerator is used as a means for lowering the liquid temperature Tw, the liquid temperature Tw is lowered to room temperature or lower, but the power consumption of the refrigerator and the initial investment cost increase and it is not easy to realize.

  Therefore, in the present embodiment, the cooling efficiency of the sheet 20 by the cooling roller 22 is improved while suppressing the occurrence of these problems.

[Configuration example 1]
1A is a cross-sectional view when the cooling roller 22 of this configuration example is cut in the axial direction, and FIG. 1B is a cross-section when the cooling roller 22 of this configuration example is cut in the diameter direction. FIG.
In the cooling roller 22 of this configuration example, a coil-shaped member 2 as a turbulent flow generating means for turbulently flowing the coolant in the outer tube 1 is arranged near the inner wall of the hollow outer tube 1 that is the cooling roller 22. It is installed. The end of the coiled member 2 in the axial direction (thrust direction) of the cooling roller is fixed by a fixing rod 60 that is a protruding member provided on the inner wall of the outer tube. Further, both ends of the outer tube 1 are open, and a flange 38 is fitted and fitted into the outer tube 1 from these openings. Further, the shaft portion of the flange 38 is press-fitted into a bearing 37 provided in the rotary joint 35. Further, a resin seal member 39 prevents liquid from leaking out of the rotary joint 35 from between the inner wall of the body portion 36 of the rotary joint 35 and the shaft portion of the flange 38.

  Further, the sheet 20 is sandwiched between the outer tube 1 of the cooling roller 22 and a conveyance belt 42 (not shown) (see FIG. 2), and the outer tube 1 rotates in the direction of the arrow in FIG. The member 22 is configured to be conveyed from the right side to the left side of the drawing.

  In FIG. 1A, when the coolant flowing into the outer tube 1 from the left side of the drawing is fed into the outer tube 1, it initially flows in a Poiseuille flow like the flow velocity profile 3 as shown in FIG. Create a similar flow field. The flow velocity profile 3 collides with the coil-shaped member 2 disposed in the vicinity of the inner wall of the outer tube 1 shown in FIGS. 1A and 1B, and the flow is disturbed. As shown in FIG. The flow may be attached to the inner wall of the outer tube 1 as shown by attachment 4 or may be peeled off as shown by separation 5.

  Here, the heat transfer rate from the inner wall of the outer tube 1 to the cooling liquid is improved at locations where flow separation or adhesion occurs. Regarding flow separation, as shown in FIG. 4, when the separation 5 of the coolant flow occurs on the inner wall surface of the outer tube 1, the position of the separation 5 is the origin, and the position downstream of the separation direction in the coolant flow direction The heat transfer coefficient at x is the flow shown in "JP Hallman Heat Transfer Engineering <Top> (Brain Book Publishing), P. 144-160, Formula (5-41)" when the flow is laminar. It is distributed like hx based on the convection heat transfer equation (2). At this time, the heat transfer coefficient theoretically increases to + ∞ at the location of the separation 5, that is, the origin (however, in terms of engineering, the heat transfer coefficient does not actually become + ∞ when x = 0).

ただし、
ｘ［ｍ］：流れの剥離点からの位置
ｈｘ［Ｗ／ｍ^２・Ｋ］：位置ｘにおける局所熱伝達率
Ｐｒ［１］：プラントル係数
Ｕ∞［ｍ／ｓ］：ローラ内壁面より十分離れた流れの主流速
ν［ｍ^２／ｓ］：動粘性率（＝粘性率／密度）
ｋ：熱伝導率

However,
x [m]: position hx [W / m ² · K] from flow separation point: local heat transfer rate Pr [1] at position x: Prandtl coefficient U∞ [m / s]: sufficiently separated from roller inner wall surface Main flow velocity ν [m ² / s]: kinematic viscosity (= viscosity / density)
k: thermal conductivity

  Many of these flow separations and adhesions occur in the vicinity of the inner wall of the outer tube 1, and the heat transfer coefficient becomes higher at each location. The transmission rate is realized, the heat flux from the roller to the cooling liquid is increased, and the cooling efficiency of the sheet-like member is dramatically improved. Therefore, when the high-temperature paper 20 is nipped and conveyed by the outer tube 1 of the cooling roller 22 and the conveyance belt 42 (not shown) (see FIG. 2), the heat of the paper 20 is removed through the wall portion of the outer tube 1. It is transmitted with high efficiency to the coolant flowing inside the tube 1, and the temperature of the paper 20 is reduced.

  Further, since the coil-shaped member 2 as the turbulent flow generating means is disposed in the vicinity of the inner wall of the outer tube 1, it does not greatly hinder the flow of the coolant flowing inside the outer tube 1. Therefore, it cannot become a large fluid resistance with respect to the coolant flowing inside the outer tube 1, and does not give a large load to the liquid feed of a pump (not shown) that feeds the coolant into the outer tube 1. Operation with low power consumption can be performed.

  In addition, the coiled member 2 as the turbulent flow generating means is a member different from the outer tube 1 and made slightly smaller than the diameter of the inner wall surface of the outer tube 1, so that the cooling roller 22 can be assembled easily. Since the coiled member 2 can be naturally fixed in the outer tube 1 by the frictional force generated between the inner wall surface of the outer tube 1 and the coiled member 2, a special fixing means is also provided. It can be easily realized without necessity. Further, since the coil-shaped member 2 can be easily detached from the outer tube 1, the maintainability of the cooling roller 22 can be improved.

  The direction of the coolant flow may be opposite to the direction shown in FIG.

  When the outer tube 1 is provided with a spiral member or protrusion, the spiral winding direction is fed in the same direction as the flow direction of the cooling liquid in consideration of the rotation direction of the outer tube 1 so that the problem of fluid resistance does not occur. It is conceivable that the winding direction causes the occurrence of

  For example, as shown in FIG. 1A, the coolant flows from the left side to the right side of the outer tube 1 (the left side is the upstream side in the coolant flow direction, the right side is the downstream side in the coolant flow direction), and FIG. b) In the case where the outer tube 1 is rotating clockwise as viewed from the downstream axial direction, the coiled member 2 tries to cause turbulent flow so as not to cause fluid resistance in the vicinity of the inner wall of the outer tube 1. Then, the winding direction of the coil-shaped member 2 that rotates clockwise together with the outer tube 1 is a right-handed winding in which the feed in the same direction as the flow direction of the coolant occurs.

  FIG. 5A is an enlarged cross-sectional view of the cooling roller 22 in which the outer tube 1 is rotated clockwise and the coil-shaped member 2 is right-handed. FIG. It is drawn. In FIG. 5A, it can be seen that the flow direction of the coolant and the feed direction of the coolant due to the rotation of the coiled member 2 are the same.

  Needless to say, in the same way, when the cooling liquid is made to flow from the left side to the right side of the sheet and the conveying direction of the sheet 20 in FIG. 1B is reversed (right direction on the sheet), the outer tube 1 is downstream in the flow direction of the cooling liquid. Since the left-handed rotation is seen from the axial direction on the side, the winding direction of the coiled member 2 at this time is left-handed. FIG. 5D is an enlarged cross-sectional view of the cooling roller 22 in which the outer tube 1 is rotated counterclockwise and the coil-shaped member 2 is counterclockwise. The flow direction of the cooling liquid and the direction of cooling liquid feeding due to the rotation of the coil-shaped member 2 are It turns out that it becomes the same direction.

  In this way, the flow direction of the coolant flowing in the outer tube 1 of the cooling roller 22 and the feed direction of the coolant due to the rotation of the coiled member 2 are configured in the same direction, so that the inside of the outer tube 1 The fluid resistance by the coil-shaped member 2 with respect to the cooling fluid flowing through can be reduced.

  On the other hand, the turbulent flow generating means provided on the inner wall (inner peripheral surface) of the outer tube is formed in a spiral shape like the coiled member 2, and the winding direction of the spiral is along the vicinity of the inner wall of the outer tube according to the rotation direction of the outer tube 1. The winding direction is such that the feed is generated in a direction opposite to the flow direction of the flowing coolant.

  In the cooling liquid near the inner wall of the outer tube 1 than the cooling roller 22 having the configuration shown in FIGS. 5A and 5D, a further turbulent flow is generated to further improve the cooling performance. . As the method, the winding direction of the coil-shaped member 2 is set to a winding direction opposite to the winding direction of the configuration shown in FIGS. 5A and 5D, and the feeding in the direction opposite to the flow direction of the coolant is performed. It was made to occur. As a result, in the vicinity of the inner wall of the outer pipe 1, a force (flow) for sending the coolant in the opposite direction by the coiled member 2 collides with the coolant flow toward the downstream in the coolant flow direction. Therefore, a more complicated and more random turbulent flow is generated, and the heat transfer efficiency from the outer tube 1 to the coolant is greatly improved.

  In contrast to the configuration shown in FIGS. 5A and 5D in which the coolant feeding direction by the coil-shaped member 2 is the same as the flow direction of the coolant flowing in the outer tube 1, the coil-shaped member 2 FIG. 5B and FIG. 5C show a configuration example in which the feeding direction of the cooling liquid is the feeding direction opposite to the flowing direction of the cooling liquid flowing in the outer tube 1.

  As shown in FIG. 5 (a) and FIG. 5 (c), when the coolant flows from the left side to the right side of the drawing and the outer tube 1 rotates clockwise when viewed from the axial direction downstream in the coolant flow direction, When the direction in which the coolant is fed by the member 2 is the same as the flow of the coolant flowing in the outer tube 1, the coiled member 2 is wound clockwise as shown in FIG. In order to set the coolant feeding direction to be opposite to the coolant flowing in the outer tube 1, the coiled member 2 is left-handed as shown in FIG.

  Further, as shown in FIGS. 5B and 5D, the coolant flows in the outer tube 1 from the left side to the right side in the drawing, but the outer tube 1 is viewed from the axial direction downstream in the coolant flow direction. Is rotated counterclockwise, when the coolant feeding direction by the coil-shaped member 2 is the same as the flow direction of the coolant flowing in the outer tube 1, the coil-shaped member 2 is moved as shown in FIG. When left-handed and the direction in which the coolant is fed by the coil-shaped member 2 is opposite to the direction of the coolant flowing through the outer tube 1, the coil-shaped member 2 is wound clockwise as shown in FIG. To do.

  The above combination is not limited. For example, the rotation direction of the outer tube 1 and the winding direction of the coiled member 2 remain the same, and only the flow direction of the cooling liquid flows in the opposite direction (from the right side to the left side of the page). 5 (a) and 5 (d), the coolant flow direction and the coolant feed direction by the coiled member 2 are opposite to each other.

  Therefore, the coolant is fed by the coiled member 2 in the direction of the coolant flow in the three-way combination of the rotation direction of the outer tube 1, the coolant flow direction, and the coolant feed direction by the coiled member 2. The winding direction of the coil-shaped member 2 is determined so that the same feed or the reverse feed occurs.

  However, care must be taken because the fluid resistance increases depending on the size of the turbulent flow generating means such as the coil-shaped member 2. For example, in the case of the coil-shaped member 2, if the wire diameter is extremely small, the effect of turbulent flow is reduced. However, the coolant feeding direction by the coil-shaped member 2 is opposite to the coolant flow direction. Even so, the fluid resistance is very small and does not cause a problem. Conversely, if the wire diameter of the coil-shaped member 2 is made extremely thick, the turbulent flow effect is increased, but the feed of the coolant by the coil-shaped member 2 is also greatly strengthened because the feed in the direction opposite to the flow direction of the coolant is greatly increased. Resistance will increase. However, the shape and the size of the turbulent flow generating means such as the coiled member 2 are respectively determined according to the specification conditions such as the flow rate of the coolant, the flow rate, the width (size) of the gap through which the coolant flows, and the cooling performance target. Since it changes corresponding to each case, it is not possible to make a general decision. Therefore, the applicant of the present application compares the optimum shape and size (for example, the wire diameter dimension) of the turbulent flow generating means by simulation and experimental evaluation so that the maximum turbulent flow effect can be obtained with the minimum fluid resistance. We decided after confirming. Further, when the turbulent flow generating means has a spiral shape like the coiled member 2, the helical pitch interval is a factor that determines the frequency of occurrence of turbulent flow and the position interval at which turbulent flow is generated. Need to be considered.

  As the turbulent flow generation means, in addition to the coil-shaped member 2, for example, a net-like member 6 as shown in FIG. Further, although not as much as the net member 6, a plurality of linear members or the like may be inserted into the outer tube 1. Alternatively, a sheet having a plurality of punch holes rounded into a cylindrical shape or a slightly thick porous medium may be inserted into the outer tube 1.

[Configuration example 2]
FIG. 7 is a cross-sectional view of the cooling roller 22 of this configuration example when cut in the axial direction. In this configuration example, as shown in FIG. 7, a coil-shaped member 2 that is a turbulent flow generating means is provided only in the vicinity of the sheet 20 in the axial direction of the outer tube 1. By providing the coil-shaped member 2 only in the vicinity of the outer tube 1 with which the high-temperature paper 20 is in contact, the coil-shaped member 2 in the outer tube 1 is not provided. Since no fluid resistance is generated by the coil-shaped member 2 with respect to the flowing coolant, the load on the pump is small, the power consumption is reduced and the durability is improved. Can be planned.

[Configuration example 3]
FIG. 8A is a cross-sectional view when the cooling roller 22 of the present configuration example is cut in the axial direction, and FIG. 8B is a cross-sectional view when the cooling roller 22 of the present configuration example is cut in the diameter direction. is there. In this configuration example, as shown in FIGS. 8A and 8B, a coil-shaped member 70 having a diameter much smaller than the diameter of the outer tube 1 is installed only in the vicinity of the paper 20 of the outer tube 1. Yes.

  As shown in FIG. 9, one end is fixedly supported at the end of the rotary joint 35 and the other end is fixed to the other end of the shaft 63 that is long in the axial direction of the cooling roller located in the outer tube 1. A hole is made in the side wall of the rod 60 in the axial direction of the cooling roller, and a thin wire 61 that is long and thin in the axial direction of the cooling roller is passed through the hole. Although not shown in FIG. 9, the opposite side in the cooling roller axial direction has the same configuration. And the coil-shaped member 70 is fastened near the inner wall of the outer tube 1 by passing the coil-shaped member 70 through the wire 61. Further, the cooling roller axial direction (thrust direction) of the coil-shaped member 70 is fixed by a fixing rod 60. With such a configuration, even if the outer tube 1 rotates, the shaft 63 whose one end is fixedly supported by the rotary joint 35 does not rotate. Therefore, the wire stretched around the solid rod 60 provided on the shaft 63 The coil-shaped member 70 passed through 61 is not displaced from the position near the paper 20 even when the outer tube 1 rotates.

  Further, as shown in FIG. 10, the fixing rod 60 may be provided so as to be swingable on the shaft 63 via a bearing 64. At this time, by providing the weight 65 at the end of the fixed rod 60 opposite to the bearing 64, the coiled member 70 can be positioned in the vicinity of the paper 20 by the weight of the weight 65.

  As a modification, in FIG. 11, a plurality of small-diameter coil-like members 70 are prepared, and the plurality of coil-like members 70 are made to correspond to the case where the contact area between the paper 20 and the outer tube 1 is wide. It is arranged only in the vicinity. The plurality of coil-shaped members 70 are provided in the vicinity of the inner wall of the outer tube 1 by providing the same number of configurations as shown in FIGS. 9 and 11 as the coil-shaped members 70.

  Thus, by arranging the coil-shaped member 70 having a smaller diameter than the coil-shaped member 2 only in the vicinity of the paper 20 in the outer tube 1, the fluid resistance by the coil-shaped member 70 can be reduced as compared with the case where the coil-shaped member 2 is provided. The load of the pump is small, the power consumption can be reduced, the durability can be improved, and the pump can be reduced by one rank, so that the cost can be reduced.

  In addition, it is good also as a structure which vibrates externally turbulent flow generation means, such as a coil-shaped member, in the meaning which promotes turbulent flow generation. In FIG. 12, the small-diameter coil-shaped member 70, which is a turbulent flow generating means, disposed near the paper 20 is vibrated by emitting vibration waves such as ultrasonic waves in a non-contact manner. Contributes to flow generation.

[Configuration Example 4]
As shown in FIG. 13A, the cooling roller 22 has a tube structure composed of an outer tube 1 and a core 31 provided with a coiled member 2 in the vicinity of the inner wall, and a narrow gap is formed between the outer tube 1 and the core 31. To do. Coolant is allowed to flow using the gap as a flow path. Then, the flow rate of the coolant is increased as compared with FIG. 5A, and the turbulent flow effect in the vicinity of the inner wall of the outer tube 1 by the coil-like member 2 is added thereto, so that the heat transfer rate is further improved by a synergistic effect. In addition, further temperature reduction of the paper 20 can be expected.

  In FIG. 13B, the core 31 shown in FIG. 13A is also provided with a coil-shaped member 32 which is a turbulent flow generating means. A turbulent flow is also generated in the vicinity of the outer wall of the core 31 by the coil-shaped member 32, and together with the turbulent flow in the vicinity of the inner wall of the outer tube due to the coil-shaped member 2 of the outer tube 1, Complex and large turbulent flow can be generated to improve the cooling performance as compared with the configuration shown in FIG.

  Further, in the case of the cooling roller 22 of this configuration example, the rotational speed component of the coolant is different between the vicinity of the inner wall of the outer pipe 1 and the vicinity of the outer wall of the core 31 by making the rotational speeds of the outer pipe 1 and the core 31 different. The heat transfer rate is further improved by promoting the generation of turbulent flow. The more the rotation of the core 31 is different from the number of rotations of the outer tube 1, such as, for example, the number of rotations of the outer tube 1 is many times that of the outer tube 1, or it is stationary and non-rotation. it can. In addition, what is necessary is just to rotate the core 31 in the reverse direction to the rotation direction of the outer tube | pipe 1 when the maximum effect is desired. In addition, the heat transfer rate is further improved by increasing the flow velocity due to the narrow gap formed by the outer tube 1 and the core 31. Further, if the cooling roller 22 is provided with turbulent flow generating means such as the coil-like member 32 in the core 31, the heat transfer rate is further improved.

[Configuration Example 5]
FIG. 14A is a cross-sectional view when the cooling roller 22 of this configuration example is cut in the axial direction, and FIG. 14B is a cross-section when the cooling roller 22 of this configuration example is cut in the diameter direction. FIG.
In the cooling roller 22 of this configuration example, an inner tube 7 is provided inside the outer tube 1, and in the vicinity of the inner wall of the outer tube 1 in a gap through which the coolant flows between the outer tube 1 and the inner tube 7. A coiled member 2 is provided as turbulent flow generating means for turbulent cooling of the coolant in the outer tube 1.

  In this configuration example, as shown in FIG. 14, the cooling roller 22 has a tube structure including the outer tube 1 and the inner tube 7, and the coolant is reciprocated in the cooling roller 22. In other words, the coolant formed by the gap formed between the outer tube 1 and the inner tube 7 is used as the forward flow path, and the cooling liquid is introduced from the left side of the drawing, and is U-turned at the right end of the outer tube 1. In this configuration, the coolant flows out toward the left side. The cooling liquid inflow / outflow path may be in the reverse direction, that is, the inside of the inner tube 7 may be the forward flow path, and the gap formed by the outer pipe 1 and the inner pipe 7 may be the return flow path.

  In the present configuration example, since the gap of the flow path of the forward flow path is narrow, the flow rate of the coolant near the inner wall of the outer pipe increases as compared with FIG. Since the turbulent flow effect is added, the heat transfer rate from the outer tube 1 to the coolant is improved. Further, if the outer diameter of the inner tube 7 is made closer to the inner diameter of the outer tube 1 to make the gap narrower, the same effect as that obtained when the core 31 shown in FIG.

  Further, in this configuration example, the joint provided with the mechanical seal for inflow and outflow of the cooling liquid into the outer tube 1 provided at the end portion in the axial direction of the cooling roller 22 is only the left side of the cooling roller 22 in the drawing, that is, Therefore, it is only necessary to provide the cooling roller 22 on one end side in the axial direction, and as a result, there is an empty space on the right side of the cooling roller 22, in other words, on the other end side in the axial direction of the cooling roller 22 where the joint means is not provided. to be born. This empty space contributes to the miniaturization of the image forming apparatus, and when the cooling roller 22 is assembled to the cooling apparatus 18 or the image forming apparatus, the assembling work of the cooling roller 22 is easily performed without being caught by the cooling liquid tube or piping. It can be performed.

  Further, in the case of the cooling roller 22 composed of the outer tube 1 and the inner tube 7, the rotation of the coolant can be performed by making the outer tube 1 and the inner tube 7 have different rotational speeds as shown in FIG. The velocity component is greatly different between the vicinity of the inner wall of the outer tube 1 and the vicinity of the outer wall of the inner tube 7, which promotes the generation of turbulent flow and further improves the heat transfer coefficient. As the rotation of the inner tube 7 is different from the number of rotations of the outer tube 1, for example, the number of rotations is many times that of the outer tube 1 or is stationary and non-rotating, the effect can be obtained. it can. If the maximum effect is desired, the inner tube 7 may be rotated in the direction opposite to the rotation direction of the outer tube 1.

  For example, as shown in FIG. 16, a magnet 81 is attached to the rotating shaft of a motor 80 provided outside the rotary joint, while a magnet 82 is also attached to the outer peripheral surface of the inner tube 7 facing the magnet 81 attached to the motor 80. It is attached, and the inner tube 7 is rotated by applying a rotational force to the magnet 82 attached to the inner tube 7 by rotating the magnet 81 attached to the motor 80 and acting between the two magnets. By controlling the number of rotations and the direction of rotation, the number of rotations and the direction of rotation of the outer tube 1 and the inner tube 7 can be made different.

  In FIG. 17B, the inner tube 7 of FIG. 17A is also provided with a coiled member 33 which is a turbulent flow generating means. A turbulent flow is also generated near the outer wall of the inner tube 7 by the coiled member 33, and is formed by the outer tube 1 and the inner tube 7 together with the turbulent flow near the inner wall of the outer tube by the coiled member 2 of the outer tube 1. The cooling performance can be further improved by generating a more complicated and larger turbulent flow in the gap.

  Further, as shown in FIGS. 18 and 19, a configuration in which a coil-like member 70 having a diameter much smaller than the diameter of the outer tube 1 is installed only in the vicinity of the paper 20 of the outer tube 1 can be adopted.

  As shown in FIG. 18, a fixed rod 60 provided with one end fixedly supported by the rotary joint 35 and the other end positioned in the outer tube 1 fixed to the other end of the shaft 63 that is long in the axial direction of the cooling roller. A hole is made in the side of the cooling roller in the axial direction of the cooling roller, and a thin wire 61 that is long and thin in the axial direction of the cooling roller is passed therethrough. And the coil-shaped member 70 is fastened near the inner wall of the outer tube 1 by passing the coil-shaped member 70 through the wire 61. Further, the end of the wire 61 opposite to the fixing rod 61 side is bent after passing the coiled member 70 through the wire 61 so that the coiled member 70 does not come out of the wire 61. Since the weight of the coil-shaped member 70 is not so heavy, it is possible to support the shaft 63 with a cantilever strength, but two or more shafts 63 may be provided to increase the strength.

  Further, as shown in FIG. 19, the fixing rod 60 may be provided so as to be swingable on the inner tube 7 via a bearing 64. At this time, by providing the weight 65 at the end of the fixed rod 60 opposite to the bearing 64, the coiled member 70 can be positioned in the vicinity of the paper 20 by the weight of the weight 65.

  Thus, by arranging the coil-shaped member 70 having a smaller diameter than the coil-shaped member 2 only in the vicinity of the paper 20 in the outer tube 1, the fluid resistance by the coil-shaped member 70 can be reduced as compared with the case where the coil-shaped member 2 is provided. The load of the pump is small, the power consumption can be reduced, the durability can be improved, and the pump can be reduced by one rank, so that the cost can be reduced.

[Configuration Example 6]
FIG. 20A is a cross-sectional view when the cooling roller 22 of this configuration example is cut in the axial direction, and FIG. 20B is a cross-section when the cooling roller 22 of this configuration example is cut in the diameter direction. FIG.
In the cooling roller 22 of this configuration example, an inner tube 7 is provided inside the outer tube 1, and a hollow cylinder 8 is inserted outside the inner tube 7. The cooling liquid flows through the narrow gap formed and the inner pipe 7. That is, the coolant is introduced from the left side of the drawing through a narrow gap formed by the outer tube 1 and the cylinder 8, and the coolant that has reached the right end of the outer tube 1 is U-turned so that the inside of the inner tube 7 is left on the page. It is configured to flow toward By providing the cylinder 8 as in this configuration example, the flow velocity in the vicinity of the inner wall of the outer tube 1 is increased and the heat transfer rate from the wall portion of the outer tube 1 to the coolant is improved compared to the case without the cylinder 8. Thus, the temperature of the paper 20 can be further reduced. The cooling liquid inflow / outflow path may be in the opposite direction, that is, the inside of the inner tube 7 may be the forward flow path, and the gap formed by the outer pipe 1 and the cylinder 8 may be the return flow path.

  In the case of the cooling roller 22, a narrow gap is formed between the outer tube 1 and the cylinder 8, and the cooling liquid flows using the narrow gap as a flow path, so that the flow rate of the cooling liquid increases as compared with FIG. Furthermore, since the turbulent flow effect in the vicinity of the inner wall of the outer tube by the coil-shaped member 2 is added to it, the heat transfer rate from the outer tube 1 to the cooling liquid is further improved by a synergistic effect, and the temperature of the paper 20 can be further reduced.

  Also in this configuration, the cooling fluid inflow / outflow coupling need only be provided at the left end of the cooling roller 22 in the drawing, so that the image forming apparatus can be downsized and the assembly workability can be improved. That is, the cooling roller 22 in FIG. 21A is a configuration combining the configurations shown in FIG. 13A and FIG. 17A, and has the advantages and effects of both.

  FIG. 21B shows a case where a coil-like member 34 which is a turbulent flow generating means is provided in the cylinder 8 of FIG. Thereby, a turbulent flow is also generated near the outer wall of the cylinder 8 by the coiled member 34, and in the gap formed by the outer tube 1 and the cylinder 8 together with the turbulent flow by the coiled member 2 of the outer tube 1. A more complicated and large turbulent flow can be generated to further improve the cooling performance. That is, the cooling roller 22 in FIG. 21B is a configuration combining the configurations shown in FIGS. 13B and 20B, and has the advantages and effects of both.

  Further, in the case of the cooling roller 22 of this configuration example, the rotational speed components of the cooling liquid are different between the vicinity of the inner wall of the outer pipe 1 and the vicinity of the outer wall of the cylinder 8 by making the rotational speeds of the outer pipe 1 and the cylinder 8 different. The heat transfer rate is further improved by promoting the generation of turbulent flow. As the rotation of the cylinder 8 is different from the number of rotations of the outer tube 1, for example, the number of rotations is many times higher than that of the outer tube 1 or is stationary and non-rotating, the effect can be obtained. . If the maximum effect is desired, the cylinder 87 may be rotated in the direction opposite to the rotation direction of the outer tube 1. In addition, the heat transfer rate is further improved by increasing the flow velocity due to the narrow gap formed by the outer tube 1 and the cylinder 8. Further, if the cooling roller 22 is provided with the turbulent flow generating means such as the coiled member 34 in the cylinder 8, the heat transfer coefficient is further improved.

  Next, FIG. 22 shows a schematic configuration diagram of a color image forming apparatus of a tandem type intermediate transfer belt system equipped with a cooling device 18 having a cooling roller 22 of the present invention.

  An intermediate transfer belt 51 as an intermediate transfer medium is stretched by a plurality of rollers, and the intermediate transfer belt 51 is configured to rotate by these rollers, and an image forming process means is disposed around the intermediate transfer belt 51. ing.

  When the rotation direction of the intermediate transfer belt 51 is indicated by an arrow a in the drawing, image formation is performed in order from the upstream side in the rotation direction of the intermediate transfer belt 51 above the intermediate transfer belt 51 and between the rollers 52 and 53. As a processing means, a first image station 54Y, a second image station 54C, a third image station 54M, and a fourth image station 54Bk are arranged. For example, in the first image station 54Y, the charging unit 10Y, the optical writing unit 12Y, the developing unit 13Y, and the cleaning unit 14Y are arranged around the drum-shaped photoconductor 11Y, and the photoconductor 11 is opposed to the intermediate transfer belt 51. A primary transfer roller 15Y as a transfer unit to the intermediate transfer belt 51 is provided at the position, 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 this embodiment, the optical writing unit 12 is an optical system using an LED as a light source, but it can also be configured by a laser optical system using a semiconductor laser as a light source, and the photosensitive member 11 is exposed according to image information. .

  Below the intermediate transfer belt 51, a sheet storage unit 19 and a sheet feeding roller 23 of the sheet 20, which is a sheet-like member, a registration roller pair 21, and a roller 55 that stretches the intermediate transfer belt 51 are interposed via the intermediate transfer belt 51. On the front surface of the intermediate transfer belt 51 at a position opposite to the secondary transfer roller 56 as a transfer means from the intermediate transfer belt 51 provided so as to face the roller 58 and the roller 58 in contact with the back surface of the intermediate transfer belt 51. A cleaning unit 59 provided in contact therewith, a thermal fixing unit 16, a cooling device 18 having a cooling roller 22 for cooling the paper 20, a paper discharge container 17 that is a discharge unit of the paper 20 after toner fixing, and the like are arranged. Yes. A paper transport path 28 extending from the paper storage unit 19 to the paper discharge storage unit 17 extends. In order to perform image formation on the back side during double-sided image formation, a paper conveyance path 29 for double-sided image formation is also provided, which reverses the paper 20 that has once passed through the cooling device 18 and conveys it again to the registration roller pair 21.

  The cooling roller 22 of the cooling device 18 is a heat receiving unit that receives the heat of the paper 20, and is connected / connected by the pipe 105 together with the radiator 103, the pump 100, and the tank 101 to which the cooling fan 104 is attached, and the cooling liquid is enclosed. ing. As shown by the arrow of the pipe 105, the cooling liquid circulation path supplies the cooling liquid cooled by the radiator 103 to the cooling roller 22, discharges it after passing through the cooling roller 22, and thereafter, tank 101, pump The cooling liquid is circulated by the rotational pressure of the pump 100 and radiated by the radiator 103 to cool the cooling liquid, that is, the cooling roller 22. The power of the pump 100, the size of the radiator 103, 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 that the cooling roller 22 should cool).

  When the image forming process is focused on the first image station 54Y, it follows the general electrostatic recording system, and the light writing unit 12Y applies the photoconductor 11Y uniformly charged by the charging unit 10Y in the dark. An electrostatic latent image is formed by exposure, and the electrostatic latent image is visualized as a toner image by the developing device 13Y. The toner image is transferred from the photoreceptor 11Y to the intermediate transfer belt 51 by the primary transfer roller 15Y. The surface of the photoreceptor 11Y after the transfer is cleaned by the cleaning means 14. The other image stations 54 have the same configuration as the first image station 54Y, and the same image forming process is performed.

  Each developing device 13 in each of the image stations 54Y, 54C, 54M, and 54Bk has a visible image forming function using different four color toners, and yellow, cyan, and magenta are used in each of the image stations 54Y, 54C, 54M, and 54Bk. If black is shared, a full color image can be formed. Therefore, while the same image forming area of the intermediate transfer belt 51 sequentially passes through the four image stations 54Y, 54C, 54M, and 54Bk, the primary provided so as to face the respective photoreceptors 11 with the intermediate transfer belt 51 interposed therebetween. If the toner images are transferred one by one on the intermediate transfer belt 51 by the transfer bias applied by the transfer roller 15, the same image forming area is assigned to each of the image stations 54Y, 54C, 54M and 54Bk. 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 51 is transferred to the paper 20. The intermediate transfer belt 51 after the transfer is cleaned by a cleaning unit 59. During transfer, the transfer bias is applied to the secondary transfer roller 56 via the intermediate transfer belt 51 on the roller 55 at the time of transfer, and the sheet 20 is placed at the nip portion between the secondary transfer roller 56 and the intermediate transfer belt 51. This is done by passing. After the transfer to the paper 20, the full-color toner image carried on the paper 20 is fixed by the heat fixing unit 16, so that a full-color final image is formed on the paper 20 and is stacked on the paper discharge storage unit 17.

  In the image forming apparatus according to the present embodiment, the paper 20 passes through the cooling device 18 disposed immediately after the heat fixing unit 16 before the paper 20 is stacked in the paper discharge storage unit 17. When passing, the paper 20 heated by the heat fixing means 16 passes while contacting the cooling roller 22 which is a heat receiving portion. Therefore, the surface of the cooling roller 22 absorbs heat from the paper 20, and this heat is absorbed. This is transmitted to the cooling liquid inside the cooling roller 22. After the heat is transferred, the high-temperature coolant is discharged from the cooling roller 22, and the coolant passes through the tank 101 and the pump 100 and is sent to the radiator 103 equipped with the cooling fan 104, where the heat is formed. Heat is exhausted outside the equipment. The coolant whose heat has been removed by the radiator 103 and lowered to near room temperature is then sent to the cooling roller 22 again. By such an exhaust heat cycle with high cooling performance by the coolant, the sheet 20 heated to the high temperature by the heat fixing means 16 is efficiently cooled. Therefore, the toner on the paper 20 can be surely cured when the paper 20 is stacked in the paper discharge accommodating portion 17. In particular, it is possible to avoid the blocking phenomenon that has been a serious problem in the double-sided image formation output.

  Embodiments of an electrophotographic image forming apparatus according to the present invention will be described below.

[Example 1]
The cooling roller 22 of the present invention was applied to a remodeling machine for an imgio Neo C600 color image forming apparatus manufactured by Ricoh. The Image Neo C600 employs the tandem indirect transfer system shown in FIG.

  The cooling roller 22 is a coil-shaped member having an outer diameter of 30.4 [mm] and a thickness of 1.1 [mm] made of aluminum and a coil thickness of 0.5 [mm] and a pitch of 6 [mm]. 2 was inserted along the inner wall of the outer tube 1 and two unidirectional flow rotary joints manufactured by Showa Giken Co., Ltd. were attached to both ends of the cooling roller so as to be sealed and rotated.

  The radiator has two aluminum corrugated types (thickness 20 [mm]) in a square shape with a side of 120 [mm] in series, and the radiator fan has the same size as the radiator and a square shaft with a side of 120 [mm] A flow fan (flow rate 2.3 [m / s]), a pump is a centrifugal type whose deadline is 50 [kPa], a tank is made of polypropylene having a volume of 700 [mL], and a pipe is made of a mixed component of butyl rubber and EPDM. As the rubber tube and the circulating coolant, -13 [° C.] antifreeze specification containing propylene glycol as a main component and containing a rust preventive was selected.

With the above configuration, 75 color double-sided continuous printing per minute is performed on the coated paper, which is a gloss coat (158 [g / m ² ]) manufactured by Oji Paper Co., Ltd., and a POD film coat S (198 [g / m ² ]). For 3 hours. Note that for the temperature measurement of the paper, a thin thermocouple is provided in the paper transport path between the fixing device and the cooling device and in the paper transport path downstream of the cooling roller 22 in the paper transport direction. The temperature when the paper contacted the thermocouple was measured. As a result, when a gloss coat manufactured by Oji Paper Co., Ltd. is used as the effect of reducing the paper temperature, the paper temperature after cooling by the cooling roller 22 is 35 [from the paper temperature before the paper is cooled by the cooling roller 22 after fixing. [C]. When the POD film coat S was used, the paper temperature after cooling by the cooling roller 22 was lowered by 30 [° C.] from the paper temperature after fixing and before the paper was cooled by the cooling roller 22. Also, there were no defects such as curling or sticking on the paper.

[Example 2]
In the second embodiment, as the cooling roller 22, an aluminum outer tube 1 having an outer diameter of 30.4 [mm] and a thickness of 1.1 [mm], an inner tube 7 made of aluminum, and a cylinder in the inner tube 7 are used. 8 and a coil-shaped member 2 having a line thickness of 0.5 [mm] and a pitch of 15 [mm] are inserted along the inner wall of the outer tube 1, and at one end of the cooling roller 22. Employs a rotating joint for bi-directional flow manufactured by Showa Giken Co., Ltd. so that it can be sealed and rotated. At this time, the inner diameter of the inner tube 7 was φ [4 mm], and the gap between the outer tube 1 and the cylinder 8 was 1.1 [mm].

  With the above configuration, 75 color double-sided continuous printing was performed for 4 hours per minute. Note that for the temperature measurement of the paper, a thin thermocouple is provided in the paper transport path between the fixing device and the cooling device and in the paper transport path downstream of the cooling roller 22 in the paper transport direction. The temperature when the paper contacted the thermocouple was measured. As a result, when a gloss coat manufactured by Oji Paper Co., Ltd. is used as the effect of reducing the paper temperature, the paper temperature after cooling by the cooling roller 22 is 39 [from the paper temperature before the paper is cooled by the cooling roller 22 after fixing. [C]. Further, when the POD film coat S was used, the sheet temperature after cooling by the cooling roller 22 was lowered by 33 [° C.] from the sheet temperature after fixing before the sheet was cooled by the cooling roller 22. Also, there were no defects such as curling or sticking on the paper.

[Comparative example]
Next, a comparative example for each example in which the coil-shaped member 2 provided in the cooling roller 22 in Example 1 or Example 2 is removed from the cooling roller 22 will be described.

  The cooling roller 22 is composed of an aluminum outer tube 1 having an outer diameter of 30.4 [mm] and a thickness of 1.1 [mm], two unidirectional flow rotary joints manufactured by Showa Giken Co., and both ends of the cooling roller. It was attached so that it could be sealed and rotated. Such a cooling rotor was applied to a remodeling machine for an imgio Neo C600 color image forming apparatus manufactured by Ricoh. The Image Neo C600 employs the tandem indirect transfer system shown in FIG.

  The radiator has two aluminum corrugated types (thickness 20 [mm]) in a square shape with a side of 120 [mm] in series, and the radiator fan has the same size as the radiator and a square shaft with a side of 120 [mm] A flow fan (flow rate 2.3 [m / s]), a pump is a centrifugal type whose deadline is 50 [kPa], a tank is made of polypropylene having a volume of 700 [mL], and a pipe is made of a mixed component of butyl rubber and EPDM. As the rubber tube and the circulating coolant, -13 [° C.] antifreeze specification containing propylene glycol as a main component and containing a rust preventive was selected.

With the above configuration, 75 color double-sided continuous printing per minute is performed on the coated paper, which is a gloss coat (158 [g / m ² ]) manufactured by Oji Paper Co., Ltd., and a POD film coat S (198 [g / m ² ]). For 3 hours. The temperature of the paper is measured by providing thin thermocouples in the paper transport path between the fixing device and the cooling device and in the paper transport path downstream of the cooling roller in the paper transport direction. The temperature when the paper contacted the thermocouple was measured. As a result, when the gloss coat manufactured by Oji Paper Co., Ltd. is used as the effect of reducing the paper temperature, the paper temperature after cooling by the cooling roller is 33 [° C.] from the paper temperature after fixing and before the paper is cooled by the cooling roller. lowered. Further, when the POD film coat S was used, the paper temperature after cooling by the cooling roller dropped by 27 [° C.] from the paper temperature after fixing and before the paper was cooled by the cooling roller. Also, there were no defects such as curling or sticking on the paper.

  From the experimental results of Example 1, Example 2 and the comparative example, the coiled member 2 is installed in the cooling roller 22 to positively generate a turbulent flow in the vicinity of the inner wall of the cooling roller 22. It can be seen that the effect of reducing the sheet temperature can be improved as compared with the case where the coil-shaped member 2 is not installed in the interior 22.

As described above, according to the present embodiment, the cooling roller 22 including the outer tube 1 that is a hollow tubular member and the like, and the pump 100 that is a cooling medium conveying unit that conveys the cooling liquid into the cooling roller 22 are provided. In the cooling device 18 that cools the paper 20 by bringing the paper 20 into contact with the cooling roller 22, turbulent flow generating means for generating turbulent flow in the coolant is provided in the vicinity of the inner wall of the outer tube 1. The coolant flow becomes turbulent near the inner wall. Thereby, replacement of the coolant having a high temperature in the vicinity of the inner wall and the coolant having a low temperature at a position away from the inner wall is actively performed. Therefore, since the temperature of the coolant near the inner wall can be made lower than when no turbulent flow generating means is provided near the inner wall, the cooling roller 22 can be effectively cooled by the coolant. As a result, the cooling efficiency of the paper 20 by the cooling roller can be improved.
Further, the turbulent flow generating means has a spiral shape, and the spiral winding direction is set to a winding direction in which a feed in the direction opposite to the flow direction of the coolant flowing in the vicinity of the inner wall of the outer tube 1 is generated. The cooling performance can be further improved by generating a further turbulent flow with respect to the cooling liquid in the vicinity of the inner wall of the paper 1, so that the cooling efficiency of the paper 20 can be improved.
Moreover, according to this embodiment, the said turbulent flow generation means can be attached or detached with respect to the outer tube | pipe 1, Therefore In order to provide a turbulent flow generation | occurrence | production means, the difficult process process of digging a groove | channel and a slit previously in the outer tube | pipe 1. Can be retrofitted without needing, and can be replaced for maintenance.
Further, according to the present embodiment, the inner tube 7 having a narrower tube structure than the outer tube 1 is included in the hollow inside of the outer tube 1 that is the tubular member, and the cooling liquid is interposed between the outer tube 1 and the inner tube 7. This is a double-pipe structure having an outer flow channel that flows and an inner flow channel through which the coolant flows in the inner tube 7. Thereby, since the flow path of the coolant can be divided between the gap between the outer tube 1 and the inner tube 7 and the inside of the inner tube 7, one is the forward path of the coolant flow and the other is the return path of the coolant flow. can do. Therefore, the inflow / outflow port of the cooling liquid can be provided on one side of the cooling roller 22 in the axial direction, and space can be saved as compared with the case where the inflow / outflow port of the cooling liquid is provided on both sides of the cooling roller 22 in the axial direction. Further, the cooling roller 22 can be easily assembled to the cooling device 18 and the image forming apparatus.
Further, according to the present embodiment, the cylinder 8 having a larger outer diameter than the inner tube 7 is attached inside the hollow of the outer tube 1 so as to enclose the inner tube 7. Therefore, the flow rate of the cooling liquid in the vicinity of the inner wall of the outer tube is increased, the heat transfer coefficient between the inner wall of the roller and the cooling liquid is increased, and the cooling efficiency of the sheet 20 is improved.
Further, according to the present embodiment, the inner tube 7 can be rotated at a different number of rotations in the same direction as the rotation direction of the outer tube 1, can be rotated in a direction opposite to the rotation direction of the outer tube 1, or in a fixed state. By being provided, the swirl speed component increases in the flow path formed by the gap between the outer tube 1 and the inner tube 7, and the generation of the turbulent flow of the coolant by the above-described continuous flow generating means can be promoted. As a result, separation and adhesion of a larger amount of coolant flow occur at various locations on the inner wall surface of the outer tube, and the cooling efficiency of the paper 20 can be further improved.
Further, according to this embodiment, the cylinder 8 can be rotated at a different rotational speed in the same direction as the rotation direction of the outer tube 1, can be rotated in a direction opposite to the rotation direction of the outer tube 1, or is provided in a fixed state. As a result, the swirl speed component increases in the flow path formed by the gap between the outer tube 1 and the cylinder 8, and the generation of the turbulent flow of the coolant by the above-described continuous flow generating means can be promoted. As a result, separation and adhesion of a larger amount of coolant flow occur at various locations on the inner wall surface of the outer tube, and the cooling efficiency of the paper 20 can be further improved.
Further, according to the present embodiment, the turbulent flow generating means is disposed in the region where the paper 20 extending in the longitudinal direction of the outer tube 1 is sandwiched, so that fluid resistance is also generated by the turbulent flow generating means in other portions. In addition, the pump load can be reduced and the power consumption can be reduced. In addition, the pump can be reduced by one rank and the cost can be reduced. Moreover, suppressing the power consumption of the pump leads to an increase in the durability time.
Further, according to the present embodiment, the turbulent flow generating means is disposed in the region where the paper 20 extending in the circumferential direction of the outer tube 1 is sandwiched, so that the fluid resistance is generated by the turbulent flow generating means in other portions. In addition to reducing the load on the pump and lowering the power consumption, it is possible to use a pump that is one rank lower and lower costs. Moreover, suppressing the power consumption of the pump leads to an increase in the durability time.
Further, according to the present embodiment, the vibration generating means that vibrates the turbulent flow generating means causes the turbulent flow generating means to vibrate, and the flow rate of the coolant near the turbulent flow generating means fluctuates and increases. Therefore, the generation of the turbulent flow of the coolant by the turbulent flow generating means as described above can be promoted. As a result, separation and adhesion of a larger amount of coolant flow occur at various locations on the inner wall surface of the outer tube, and the cooling efficiency of the paper 20 can be further improved.
Moreover, according to this embodiment, since the turbulent flow generating means is a coil-shaped member, the cooling roller 22 of the present invention can be easily realized at low cost .
Also, according to this embodiment, the core 31 is a core member encloses the hollow interior of the outer tube 1, the cooling liquid flows through the space formed by the outer tube 1 and the core 31 provided with turbulence generating means It has a flow path. As a result, since the coolant flows through the narrow gap flow path formed by including the core 31, the flow rate of the coolant in the vicinity of the inner wall of the outer tube increases, the heat transfer coefficient between the roller inner wall and the coolant increases, As a result, the cooling efficiency of the paper 20 can be improved.
Further, according to the present embodiment, the second turbulent flow generating means for generating the turbulent flow in the coolant is provided in the vicinity of the outer peripheral surface of the core 31, so that a more complicated and large turbulent flow is generated in the flow path gap. In addition, the heat transfer coefficient between the roller inner wall and the cooling liquid is further increased, and the cooling efficiency of the paper 20 can be improved.
Further, according to the present embodiment, by providing the second turbulent flow generating means for generating the turbulent flow in the coolant near the outer peripheral surface of the inner pipe 7, more complicated and large turbulent flow is generated in the channel gap. As a result, the heat transfer rate between the inner wall of the roller and the coolant is further increased, and the cooling efficiency of the paper 20 can be improved.
Further, according to the present embodiment, the second turbulent flow generating means for generating the turbulent flow in the coolant is provided in the vicinity of the outer peripheral surface of the cylinder 8, so that a more complicated and large turbulent flow is generated in the flow passage gap. In addition, the heat transfer coefficient between the roller inner wall and the cooling liquid is further increased, and the cooling efficiency of the paper 20 can be improved.
Further, according to this embodiment, the core 31 can be rotated at a different number of rotations in the same direction as the rotation direction of the outer tube 1, can be rotated in the direction opposite to the rotation direction of the outer tube 1, or is provided in a fixed state. As a result, in the narrow gap flow path formed by including the core 31 in the outer tube 1, the swirl speed component increases, and the above-described turbulent flow generating means promotes the generation of the turbulent flow of the coolant. Can do. As a result, separation and adhesion of a larger amount of coolant flow occur at various locations on the inner wall surface of the outer tube, and further cooling efficiency of the sheet 20 is improved.
Further, according to the present embodiment, the toner image forming unit that forms a toner image on the paper 20, the thermal fixing unit 16 that fixes the toner image formed on the paper 20 to the paper 20 at least by heat, and the thermal fixing. In the image forming apparatus provided with a cooling means for cooling the paper 20 on which the toner image is fixed by the means 16, the cooling device 18 having the cooling roller 22 of the present invention is used as the cooling means, thereby cooling the paper 20. Efficiency can be improved.

DESCRIPTION OF SYMBOLS 1 Outer tube 2 Coil-shaped member 3 Flow velocity profile 4 Adhesion 5 Separation 6 Net-like member 7 Inner tube 8 Cylinder 9 Excitation means 10 Charging means 11 Photoconductor 12 Optical writing means 13 Developing device 14 Cleaning means 15 Primary transfer roller 16 Thermal fixing means DESCRIPTION OF SYMBOLS 17 Paper discharge accommodating part 18 Cooling device 19 Paper accommodating part 20 Paper 21 Registration roller pair 22 Cooling roller 23 Paper feed roller 28 Paper conveyance path 29 Paper conveyance path 31 Core 32 Coil-shaped member 33 Coil-shaped member 34 Coil-shaped member 35 Rotary joint 36 Body 37 Bearing 38 Flange 39 Seal member 40 Roller 41 Roller 42 Conveying belt 43 Upper guide 44 Bracket 51 Intermediate transfer belt 52 Roller 53 Roller 55 Roller 56 Secondary transfer roller 58 Roller 59 Cleaning means 60 Fixing rod 61 Wire 62 Wire hook 63 Shaft 64 Bearing 65 Weight 70 Coiled member 80 Motor 81 Magnet 82 Magnet 100 Pump 101 Tank 103 Radiator 104 Cooling fan 105 Piping

JP 2006-003819 A

Claims (16)

A cooling roller made of a hollow tubular member;
Cooling medium conveying means for conveying a cooling liquid into the tubular member,
In the cooling device that cools the sheet-like member by bringing the sheet-like member into contact with the cooling roller,
Turbulent flow generating means for generating turbulent flow in the coolant is provided near the inner wall of the tubular member ,
The turbulent flow generation means has a spiral shape, and the winding direction of the spiral shape is a winding direction in which a feed in a direction opposite to the flow direction of the coolant flowing in the vicinity of the inner wall of the outer tube as the tubular member is generated. A cooling device characterized by. The cooling device of claim 1.
The cooling apparatus according to claim 1, wherein the turbulent flow generating means is detachable from the tubular member. The cooling device according to claim 1 or 2,
Enclosing the inner tube of the tubular structure than the outer tube to the hollow interior of the upper Kigai tube, an outer flow path flows between the outer tube and the inner tube the cooling liquid, and, is the internal tube cooling liquid A cooling device having a double-pipe structure having an inner flow path. The cooling device according to claim 3.
A cooling device, wherein a cylinder having an outer diameter larger than that of the inner tube is attached inside the hollow of the outer tube so as to enclose the inner tube. The cooling device according to claim 3.
The inner tube can be rotated at a different rotational speed in the same direction as the rotation direction of the outer tube, can be rotated in a direction opposite to the rotation direction of the outer tube, or is provided in a fixed state. Cooling system. The cooling device according to claim 4.
The cooling is characterized in that the cylinder can be rotated at a different rotational speed in the same direction as the rotation direction of the outer tube, can be rotated in a direction opposite to the rotation direction of the outer tube, or is provided in a fixed state. apparatus. The cooling device according to claim 1, 2, 3, 4, 5 or 6.
The cooling device according to claim 1, wherein the turbulent flow generating means is disposed in a region where the sheet-like member across the longitudinal direction of the outer tube is sandwiched. The cooling device according to claim 1, 2, 3, 4, 5 or 6.
The cooling device according to claim 1, wherein the turbulent flow generating means is disposed in a region where the sheet-like member across the circumferential direction of the outer tube is sandwiched. The cooling device according to claim 1, 2, 3, 4, 5, 6, 7 or 8.
A cooling device comprising vibration means for applying vibration to the turbulent flow generation means. The cooling device according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9,
The turbulent flow generating means is a coiled member. The cooling device of claim 1 .
A cooling apparatus comprising a core member enclosed in a hollow interior of the outer tube, and a flow path through which a coolant flows in a gap formed by the outer tube provided with the turbulent flow generation means and the core member. The cooling device of claim 11 , wherein
A cooling device comprising a second turbulent flow generating means for generating a turbulent flow in the coolant near the outer peripheral surface of the core member. The cooling device according to claim 3.
A cooling device comprising a second turbulent flow generating means for generating a turbulent flow in the coolant near the outer peripheral surface of the inner pipe. The cooling device according to claim 4.
A cooling device comprising second turbulent flow generating means for generating turbulent flow in the coolant near the outer peripheral surface of the cylinder. The cooling device of claim 11 , wherein
The core member can be rotated at a different rotational speed in the same direction as the rotation direction of the outer tube, can be rotated in a direction opposite to the rotation direction of the outer tube, or is provided in a fixed state. Cooling system. 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;
As the cooling means, according to claim 1,2,3,4,5,6,7,8,9,10,11,12,13,1 4 or an image, which comprises using a cooling apparatus 15 Forming equipment.

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