JP2017156645A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that has an insulating sleeve with a slit interposed between an outer peripheral surface of a rotation shaft and an inner peripheral surface of a bearing member of a fixing rotating body (fixing roller) and a pressure rotating body (pressure roller), and has prevented the heat insulating sleeve from being twisted due to an influence of thermal expansion of the rotation shaft so as not to generate an abnormal noise; and an image forming apparatus including the same.SOLUTION: A cylindrical heat insulating sleeve 22 is interposed between an outer peripheral surface of a rotation shaft of a pressure roller and an inner peripheral surface of a rolling bearing. The heat insulating sleeve 22 is divided by a slit 25 at one place in the circumferential direction, and both ends divided are fit to each other with a play to be movable in a direction along the circumferential direction and the center line of a sleeve hole.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fixing device that fixes a toner image onto a recording medium by passing a recording medium carrying a toner image between a fixing rotator and a pressure rotator, and an image forming apparatus including the fixing device.

  In the fixing device disclosed in Patent Document 1, a heat insulating sleeve is interposed between the outer peripheral surface of the rotating shaft of the fixing roller and the inner peripheral surface of the rolling bearing to prevent the heat of the fixing roller from being transmitted to the rolling bearing. ing.

  12 and 13 show a heat insulation sleeve 101 of a conventional example as used in Patent Document 1, and this heat insulation sleeve 101 includes a cylindrical sleeve main body 102. The sleeve main body 102 is divided by a slit 103 extending in a direction along the sleeve center line at one place in the circumferential direction, and the slit 103 widens against the thermal expansion of the rotation axis of the fixing roller, so that the rotation axis of the fixing roller. It is possible to prevent the thermal insulation sleeve 101 from being damaged.

  In FIGS. 12 and 13, reference numeral 104 denotes a flange formed on one side surface of the sleeve main body 102, and the heat insulating sleeve 101 is interposed between the outer peripheral surface of the rotation shaft of the fixing roller and the inner peripheral surface of the rolling bearing. In this state, the flange 104 comes into contact with the inner ring of the rolling bearing from the side. Reference numeral 105 denotes a plurality of anti-slip protrusions formed on the entire outer peripheral surface of the sleeve body 102 at intervals in the circumferential direction. The heat insulating sleeve 101 is connected to the outer peripheral surface of the rotating shaft of the fixing roller and the inner periphery of the rolling bearing. The protrusion 105 engages with a recess formed at a circumferential interval on the entire inner peripheral surface of the inner ring of the rolling bearing in a state of being interposed between the two surfaces.

JP-A-6-337608

  However, in such a fixing device, during the thermal expansion of the rotating shaft of the fixing roller, the force acting on the heat insulating sleeve 101 along with the expansion of the slit 103 of the heat insulating sleeve 101 is increased from the inside of the sleeve hole to the outer diameter direction. In addition, it also acts in the direction along the sleeve hole center line. For this reason, the both ends parted by the slit 103 of the heat insulating sleeve 101 move in directions opposite to each other in the direction along the sleeve hole center line and are twisted, and abnormal noise is generated when the twist is released. This phenomenon can occur not only in the fixing roller but also in the pressure roller.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an outer peripheral surface of a rotating shaft of a fixing rotator (fixing roller) or a pressure rotator (pressure roller) and an inner periphery of a bearing member. Provided are a fixing device in which a heat insulating sleeve having a slit interposed between a surface and a slit is prevented from being twisted by the influence of thermal expansion of a rotating shaft so that abnormal noise is not generated, and an image forming apparatus including the fixing device It is to be.

  The fixing device according to the present invention is a fixing device for fixing a toner image on a recording medium by passing a recording medium carrying a toner image between a fixing rotator and a pressure rotator. At least one of the body and the pressure rotating body has a cylindrical heat insulating sleeve interposed between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing member, and the heat insulating sleeve is provided at one place in the circumferential direction. The both ends of the divided part are fitted with play so as to be movable in the circumferential direction and the direction along the center line of the sleeve hole.

  According to this, the thermal expansion of the rotating shaft is absorbed by the spread of the slit, and the heat insulating sleeve is not damaged. At this time, even if the force acting on the heat insulation sleeve acts in the direction along the sleeve hole center line, the opposite end portions separated by the slits of the heat insulation sleeve do not play back in the direction along the sleeve hole center line. It is possible to prevent abnormal noise generated due to the opening of the twist without being twisted by being restricted by the fitting.

  In this case, the one end portion of the heat insulating sleeve that is divided has a fitting portion that protrudes toward the other end portion and has a distal end side that is wider than the root in the direction along the center line of the sleeve hole, and the heat insulating sleeve is divided. The other end portion has an insertion portion that is opened to the one end portion side, and the opening is formed narrower in the direction along the sleeve hole center line than the back side. It is desirable that the fitting portion is fitted into the fitting portion.

  According to this, even if the rotating shaft is thermally expanded, both end portions divided by the slits of the heat insulating sleeve are not separated more than necessary, and excessive deformation of the heat insulating sleeve is prevented.

  It is preferable that the fitting portion is formed to protrude in a trapezoidal shape, and the fitting portion is formed to be cut out in a trapezoidal shape larger than the outer shape of the fitting portion.

  According to this, since the side surface of the insertion portion and the side surface of the insertion portion are linearly inclined with respect to each other, it is possible to easily set the timing at which both side surfaces come into contact with each other at the time of thermal expansion of the rotating shaft.

  The insertion portion may be formed to protrude in a circular shape, and the insertion portion may be formed to be cut out in a circular shape larger than the outer shape of the insertion portion.

  Further, both the divided end portions of the heat insulating sleeve are formed to be thin and overlap each other in the radial direction, and a fitting portion protruding in the radial direction is formed in one of the overlapping portions, and the other portion of the overlapping portion is It is also possible to have a configuration in which a fitted portion that opens to the side of the fitted portion is formed larger than the outer shape of the fitted portion, and the divided end portions are fitted by fitting the fitted portion into the fitted portion. .

  Also by this, even if the rotating shaft is thermally expanded, both ends separated by the slit of the heat insulating sleeve are not separated more than necessary, and excessive deformation of the heat insulating sleeve is prevented.

  An image forming apparatus according to the present invention includes the fixing device.

  According to the present invention, in a state where the slit for absorbing the thermal expansion of the rotating shaft is secured, the reverse movement of the heat insulating sleeve in the direction along the sleeve hole center line is restricted, and the direction along the sleeve hole center line is controlled. An abnormal sound generated due to the release of the twist can be prevented.

FIG. 1 is a schematic diagram showing the internal structure of the image forming apparatus. FIG. 2 is an external perspective view of the fixing device. FIG. 3 is an external perspective view of the periphery of the bearing portion of the pressure roller. FIG. 4 is a perspective view showing the pressure roller and the bearing portion in a cut state. FIG. 5 is a perspective view of the heat insulating sleeve. FIG. 6 is an enlarged plan view showing a slit portion of the heat insulating sleeve. FIG. 7 is a view corresponding to FIG. 6 in which both divided ends of the heat insulating sleeve are moved away from each other. FIG. 8 is a view corresponding to FIG. 6 in which both divided end portions of the heat insulating sleeve try to move in opposite directions in the sleeve hole center line direction. FIG. 9 is a diagram corresponding to FIG. FIG. 10 is a diagram corresponding to FIG. FIG. 11 is an enlarged side view showing a slit portion of the heat insulating sleeve of the second modification. FIG. 12 is a perspective view of a conventional heat insulation sleeve. FIG. 13 is an enlarged plan view showing a slit portion of a conventional heat insulating sleeve.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment.

  FIG. 1 shows an image forming apparatus 1 including a laser printer. In the image forming apparatus 1, a sheet feeding unit 3, an image forming unit 4, and a fixing device 5 are accommodated in a casing 2 in order from the upstream side to the downstream side along the sheet conveyance path L. The downstream end of the paper transport path L reaches the paper discharge unit 6 provided on the upper surface of the housing 2. In the paper transport path L, a plurality of transport rollers 7 that transport the paper (recording medium) P while being sandwiched are arranged.

  The paper feed unit 3 includes a paper feed cassette 8 in which the paper P is accommodated, and a pickup roller 9 for taking out the paper P in the paper feed cassette 8 and sending it out to the paper transport path L. The paper P sent out from the paper feed cassette 8 is supplied to the image forming unit 4 by the transport roller 7.

  The image forming unit 4 transfers a toner image based on predetermined image data (for example, image data of an original image received from an external terminal) to the paper P supplied from the paper supply unit 3 and also transfers the paper after transfer. P is supplied to the fixing device 5.

  In FIG. 1, 10 is a photosensitive drum, 11 is a charger for uniformly charging the circumferential surface of the photosensitive drum 10, and 12 is a predetermined image data by irradiating the circumferential surface of the photosensitive drum 10 with laser light. An exposure apparatus for forming a corresponding electrostatic latent image, 13 is a developing unit that supplies toner to the electrostatic latent image on the circumferential surface of the photosensitive drum 10 to visualize the toner image, and 14 is transferred to a transfer roller 14a. A transfer device for transferring a toner image formed on the circumferential surface of the photosensitive drum 10 to the paper P by applying a bias, and a cleaning device 15 for cleaning the toner remaining on the circumferential surface of the photosensitive drum 10 after the transfer , 16 are static eliminators that remove residual charges on the circumferential surface of the photosensitive drum 10, and the image forming unit 4 is constituted by these.

  The fixing device 5 is a belt fixing system in which a fixing rotator is a fixing belt 17, and includes a fixing belt 17 and a pressure roller (pressure rotator) 18 in a housing 19. FIG. 2 is an external perspective view of the fixing device 5, and 20 is a paper discharge port. 3 and 4 show the inside of the housing 19, FIG. 3 is an external perspective view of the periphery of the bearing portion of the pressure roller 18, and FIG. 4 is a perspective view showing the pressure roller 18 and the bearing portion cut away. FIG. The pressure roller 18 is in pressure contact with the fixing belt 17, and the paper P carrying the toner image T is sandwiched between the fixing belt 17 to form a nip portion that melts and fixes the toner image on the paper P.

  The paper P on which the toner image is fixed by the fixing device 5 is sent out from the paper discharge port 20 to the downstream side of the paper transport path L by passing between the fixing belt 17 and the pressure roller 18, and the transport roller. 7 is discharged to the paper discharge unit 6.

  As shown in FIGS. 3 and 4, the pressure roller 18 includes an outer peripheral surface of a rotating shaft 18 a protruding from both ends, and an inner peripheral surface of a rolling bearing (bearing member) 21 provided on the fixed side in the housing 19. A cylindrical heat insulation sleeve 22 interposed between the two and the roller bearing 21 is rotatably supported via the heat insulation sleeve 22. This heat insulating sleeve 22 prevents the heat of the pressure roller 18 from being transmitted to the rolling bearing 21. 3 and 4, reference numeral 23 denotes a drive shaft for transmitting the rotational force of a drive motor (not shown) to the pressure roller 18.

  The heat insulating sleeve 22 is integrally formed of a resin having excellent heat insulating properties, such as polyphenylene sulfide (PPS).

  As shown in FIG. 5, the heat insulating sleeve 22 includes a cylindrical sleeve body 24. The sleeve body 24 is divided by a slit 25 extending in a direction along the sleeve center line at one place in the circumferential direction, and the slit 25 expands against the thermal expansion of the rotating shaft 18a of the pressure roller 18 so that pressure is applied. The thermal expansion of the rotating shaft 18a of the roller 18 can be absorbed, and damage to the heat insulating sleeve 22 can be prevented.

  That is, the relationship between the thermal expansion coefficient of the thermal insulation sleeve 22 and the thermal expansion coefficient of the rotary shaft 18a is the thermal insulation sleeve 22 <the rotary shaft 18a.

  At this time, when the gap of the slit 25 of the sleeve body 24 is ΔL1, the amount of change ΔL2 in the circumference due to the thermal expansion of the rotating shaft 18a is ΔL1 ≧ ΔL2.

  Also, ΔL (1 and 2) = L × α × ΔT.

L: Outer shaft circumference (mm) and sleeve inner circumference (mm) (excluding gaps)
α: Thermal expansion coefficient
ΔT: Temperature during use (° C)-Temperature before use (° C)
A flange 26 is integrally formed on one side surface of the sleeve body 24, and the heat insulating sleeve 22 is interposed between the outer peripheral surface of the rotary shaft 18 a of the pressure roller 18 and the inner peripheral surface of the rolling bearing 21. The flange 26 comes into contact with the inner ring of the rolling bearing 21 from the side.

  A plurality of anti-slip protrusions 27 are formed on the entire outer peripheral surface of the sleeve body 24 at intervals in the circumferential direction, and the heat insulating sleeve 22 is connected to the outer peripheral surface of the rotary shaft 18 a of the pressure roller 18 and the rolling bearing 21. In a state of being interposed between the inner peripheral surface and the inner peripheral surface, the protrusion 27 engages with a concave portion (not shown) formed at a circumferential interval on the entire inner peripheral surface of the inner ring of the rolling bearing 21. It has become.

  As shown in an enlarged view in FIG. 6, one end portion (lower end portion in FIG. 6) of the heat insulating sleeve 22 projects toward the other end portion (upper end portion in FIG. 6), and the distal end side is the root. In addition, it has a fitting portion 28 formed so as to protrude in a trapezoidal shape in the direction along the center line of the sleeve hole.

  The other end portion (the upper end portion in FIG. 6) of the heat insulation sleeve 22 opens toward one end portion (the lower end portion in FIG. 6), and the opening is closer to the sleeve hole center line than the back side. It has the insertion part 29 cut | disconnected and formed in the trapezoid shape narrowly in the direction in alignment. The cut-out shape of the fit-in portion 29 is larger than the outer shape of the fit-in portion 28, and therefore, the divided both ends are fitted along the circumferential direction and the sleeve hole center line when the fit-in portion 28 is fitted into the fit-in portion 29. It fits with play so that it can move in the direction.

  By the way, as shown in FIGS. 12 and 13, in the conventional heat insulating sleeve 101 in which the slit 103 is simply provided, the thermal expansion of the rotating shaft of the fixing roller or the pressure roller causes heat insulation as the slit 103 expands. The force acting on the sleeve 101 acts not only in the outer diameter direction from the inside of the sleeve hole but also in the direction along the center line of the sleeve hole. For this reason, the both ends parted by the slit 103 of the heat insulating sleeve 101 move in directions opposite to each other in the direction along the sleeve hole center line and are twisted, and abnormal noise is generated when the twist is released.

  However, in the present embodiment, as described above, the heat insulating sleeve 22 is divided by the slit 25 at one place in the circumferential direction, and the divided both ends can move in the circumferential direction and the direction along the sleeve hole center line. It fits with play.

  Therefore, even if the rotating shaft 18a of the pressure roller 18 is thermally expanded, the thermal expansion is absorbed by the slit 25 spreading, and the heat insulating sleeve 22 can be prevented from being damaged. Even if the force acting on the sleeve hole center line is applied in the direction along the sleeve hole center line, both ends separated by the slit 25 of the heat insulating sleeve 22 are fitted with play in the reverse direction along the sleeve hole center line. It is possible to prevent the occurrence of abnormal noise due to the twist being released.

  Further, the fitting end 28 of one end portion (lower end portion in FIG. 6) of the heat insulation sleeve 22 is formed wider in the direction along the sleeve hole center line than the root, so that the heat insulation sleeve 22 is divided. The fitted portion 29 of the other end portion (upper end portion in FIG. 6) is opened to one end portion side, and the opening is formed to be narrower in the direction along the sleeve hole center line than the back side. 28 is inserted into the insertion portion 29 and the divided ends are fitted, so that both ends separated by the slit 25 of the heat insulating sleeve 22 even if the rotating shaft 18a of the pressure roller 18 is thermally expanded. The portions can be prevented from being unnecessarily separated, and excessive deformation of the heat insulating sleeve 22 can be prevented.

  Further, the insertion portion 28 is formed in a trapezoidal shape, and the insertion portion 29 is cut out in a trapezoidal shape larger than the outer shape of the insertion portion 28 so that the side surface of the insertion portion 28 and the side surface of the insertion portion 29 are mutually connected. Since it is inclined linearly, it is possible to easily set the timing at which both side surfaces come into contact during the thermal expansion of the rotating shaft 18a of the pressure roller 18.

(Modification 1)
FIG. 9 is a diagram corresponding to FIG. The same portions as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the first modification, the insertion portion 28 is formed to protrude in a circular shape, and the insertion portion 29 is formed in a circular shape that is larger than the outer shape of the insertion portion 28. Accordingly, the divided both ends of the heat insulating sleeve 22 are fitted with play so that the fitting portion 28 is fitted in the fitting portion 29 and can move in the circumferential direction and the direction along the sleeve hole center line.

  Even in the first modification, even if the rotating shaft 18a of the pressure roller 18 is thermally expanded, the thermal expansion is absorbed by the slit 25 spreading and the breakage of the heat insulating sleeve 22 is prevented, as in the above embodiment. Can do.

  At this time, even if the force acting on the heat insulation sleeve 22 acts in the direction along the sleeve hole center line, both ends separated by the slit 25 of the heat insulation sleeve 22 are reversed in the direction along the sleeve hole center line. The movement of the direction is restricted by the fitting with play and does not twist, and it is possible to prevent the generation of abnormal noise due to the release of the twist.

  Furthermore, even if the rotating shaft 18a of the pressure roller 18 is thermally expanded, both ends separated by the slit 25 of the heat insulating sleeve 22 can be prevented from being unnecessarily separated, and excessive deformation of the heat insulating sleeve 22 can be prevented. Can do.

(Modification 2)
FIG. 10 is a diagram corresponding to FIG. FIG. 11 is an enlarged side view showing 25 slits of the heat insulating sleeve 22 of the second modification. The same portions as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the second modified example, both the divided end portions of the heat insulating sleeve 22 are thinly formed and overlapped with each other in the radial direction, and radially inward of one of the overlapping portions (the lower overlapping portion in FIG. 11). A protruding fitting portion 28 is formed, and a fitting portion 29 including a through hole that opens to the fitting portion 28 side is formed on the other of the overlapping portions (upper overlapping portion in FIG. 11) than the outer shape of the fitting portion 28. ing. The fitted portion 29 may be a bottomed concave portion. Accordingly, the divided both ends of the heat insulating sleeve 22 are fitted with play so that the fitting portion 28 is fitted in the fitting portion 29 and can move in the circumferential direction and the direction along the sleeve hole center line.

  Also in this modified example 2, as in the above-described embodiment, even if the rotating shaft 18a of the pressure roller 18 is thermally expanded, the thermal expansion is absorbed by the slit 25 spreading, and damage to the heat insulating sleeve 22 is prevented. Can do.

  At this time, even if the force acting on the heat insulation sleeve 22 acts in the direction along the sleeve hole center line, both ends separated by the slit 25 of the heat insulation sleeve 22 are reversed in the direction along the sleeve hole center line. The movement of the direction is restricted by the fitting with play and does not twist, and it is possible to prevent the generation of abnormal noise due to the release of the twist.

  Furthermore, even if the rotating shaft 18a of the pressure roller 18 is thermally expanded, both ends separated by the slit 25 of the heat insulating sleeve 22 can be prevented from being unnecessarily separated, and excessive deformation of the heat insulating sleeve 22 can be prevented. Can do.

  In addition, in the said embodiment and the modification 1, although the case where the insertion part 28 was trapezoid shape or circular shape was illustrated, not only this but rectangular shape, elliptical shape, etc. may be sufficient, and the insertion part 29 is the What is necessary is just to form a notch slightly larger than the external shape of the insertion part 28.

  Furthermore, in the above-described embodiment, the fixing device 5 is exemplified by a belt fixing method in which the fixing rotator is the fixing belt 17, but may be a roller fixing method in which the fixing rotator is a fixing roller. In this case, similarly to the pressure roller 18, the heat insulating sleeve 22 may be interposed between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the rolling bearing 21, or the fixing roller and the pressure roller. The heat insulating sleeve 22 may be interposed only in one of the 18.

  In the above embodiment, the example in which the image forming apparatus 1 is a printer has been described. However, the present invention is not limited to this. For example, the image forming apparatus 1 may be a copying machine, a facsimile machine, a multifunction machine, or the like. Good.

  As described above, the present invention includes a fixing device for fixing a toner image to a recording medium by passing a recording medium carrying a toner image between a fixing rotator and a pressure rotator, and the same. This is useful for an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing apparatus 17 Fixing belt (fixing rotary body)
18 Pressure roller (Pressure rotating body)
18a Rotating shaft 21 Rolling bearing (bearing member)
22 Insulating sleeve 25 Slit 28 Inserting portion 29 Inserting portion P Paper (recording medium)

Claims (6)

A fixing device for fixing a toner image on a recording medium by passing a recording medium carrying a toner image between a fixing rotator and a pressure rotator,
At least one of the fixing rotator and the pressure rotator has a cylindrical heat insulating sleeve interposed between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing member,
The heat insulating sleeve is divided by a slit at one place in the circumferential direction, and both divided ends are fitted with play so as to be movable in the circumferential direction and the direction along the sleeve hole center line. Fixing device. The fixing device according to claim 1,
The one end portion of the heat insulating sleeve that has been divided has a fitting portion that protrudes toward the other end portion side and has a distal end side that is formed wider in the direction along the sleeve hole center line than the root,
The other end portion of the heat insulating sleeve that has been divided has an insertion portion that opens to the one end portion side, and the opening is formed narrower in the direction along the sleeve hole center line than the back side,
The fixing device in which the divided ends are fitted by fitting the fitting portion into the fitting portion. The fixing device according to claim 2,
The fixing device, wherein the fitting portion is formed to protrude in a trapezoidal shape, and the fitting portion is formed to be cut out in a trapezoidal shape larger than the outer shape of the fitting portion. The fixing device according to claim 2,
The fixing device, wherein the insertion portion is formed to protrude in a circular shape, and the insertion portion is formed to be cut out in a circular shape larger than the outer shape of the insertion portion. The fixing device according to claim 1,
Both the separated end portions of the heat insulating sleeve are formed thin and overlap each other in the radial direction, and a fitting portion protruding in the radial direction is formed on one of the overlapping portions, and the fitting portion is formed on the other of the overlapping portions. A fitted portion that opens larger than the outer shape of the fitted portion side is formed,
The fixing device in which the divided ends are fitted by fitting the fitting portion into the fitting portion.   An image forming apparatus comprising the fixing device according to claim 1.

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