JP2014109596A - Slide bearing and fixation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce, in a slide bearing 23 for supporting a shaft portion 1a of a rotary body 1 configured to rotate while receiving an applied pressure P from a direction orthogonal to a rotation axis direction, a force acting on the bearing and reduce abrasion wear of the bearing.SOLUTION: A slide bearing includes: a first slide bearing part 3 supported by a fixed frame member 12 and rotatably supporting a shaft part 1a; and at least one second slide bearing part 5 arranged neighboring the first slide bearing part 3 and rotatably supporting the shaft part 1a, the second slide bearing part 5 is pressurized with an applied pressure F smaller than the applied pressure P, in a direction opposite to pressurizing of the applied pressure P by an elastic member 6.

Description

  The present invention relates to a sliding bearing and a fixing device for fixing a toner image on a recording material.

  For example, two types of bearings such as a rolling bearing or a sliding bearing have been mainly used as a bearing of a conveying roller (rotating body) in a paper conveying apparatus such as a printer, a copying machine, and a FAX.

  A representative example of a rolling bearing is a ball bearing. Advantages include low rolling resistance due to rolling friction, durability and heat resistance. For this reason, it is mainly used for high-speed and long-life equipment, particularly for a bearing of a fixing device having a large rotational load resistance and heat. The problem is the high cost.

  As a representative of the sliding bearing, there is a resin bearing. Generally, a molding resin material such as polyacetal resin is used, and the shaft is held at a predetermined position while sliding with the shaft of the transport roller. As an advantage, it can be manufactured at low cost. The problem is that the rotational resistance and durability of the ball bearing are inferior.

  Specifically, as the durability progresses, the bearing wears, and the position of the supporting roller (position of the rotation center axis) moves to change the position of the paper (sheet) entering the roller. Cause problems. Further, movement of the position of the gear provided on the roller shaft causes problems such as vibration and noise. For this reason, it is mainly used for low-speed and short-life equipment.

  In addition, a special resin material having heat resistance such as PPS resin may be used at a location where high temperature and high pressure are applied such as a fixing device.

  There has been a demand for improving the durability of a plain bearing, and materials that are resistant to wear have been developed as in Patent Documents 1 and 2, and attempts have been made to expand the usage range of inexpensive plain bearings as much as possible. It was.

JP 2002-31140 A Japanese Patent Laid-Open No. 11-5990

  As a demand from the market in recent years, it is required to manufacture a product at a low cost, and at the same time, it is also required to increase the speed of the product. When the speed of the product is increased, it is necessary to increase the pressure in order to secure the fixing property, particularly in the fixing device of the image forming apparatus. In general, the product (PV value) of the pressure received by the bearing and the shaft peripheral speed (PV value) is used as an index representing the load on the bearing. However, when the fixing device is speeded up, both the pressure and speed received by the bearing are severe. Direction.

  It is difficult to satisfy all of these requirements (that is, it can be manufactured at low cost and has sufficient durability and suppresses problems such as wear) using conventional bearings.

  Although the range of application of plain bearings has been expanded due to the improvement of materials, the range is limited. In addition, specially developed materials are more expensive than general materials, which also becomes an obstacle to manufacturing at low cost and can only be developed and manufactured by those who have special know-how. Therefore, it is only possible to select it in the device design, and it is difficult to avoid the problem by devising the device design.

  As another problem, when a sliding bearing is used, there is another problem that wear is accelerated when the bearing and shaft shaving powder is caught in the sliding portion.

  In view of the above problems, an object of the present invention is to propose a sliding bearing that is inexpensive and can ensure durability without depending on the performance of the material, and a fixing device using the bearing. Another object of the present invention is to propose a bearing and a sliding bearing that prevents the shaving powder of the shaft from being caught in the sliding portion and further improves the durability, and a fixing device using the bearing.

  A typical configuration of a sliding bearing according to the present invention for achieving the above object is a sliding bearing that receives a shaft portion of a rotating body that receives a load due to a pressure applied from a direction orthogonal to a rotating axis direction. A first sliding bearing portion supported by a fixed frame member and rotatably supporting the shaft portion so as to position the rotating body at a predetermined position; and at least adjacent to the first sliding bearing portion A second sliding bearing portion that is arranged in one and rotatably supports the shaft portion, and is pressed with an applied pressure smaller than the applied pressure in a direction opposite to the applied pressure direction by an elastic member. And a second sliding bearing portion formed.

  According to the present invention, the pressure applied to the first sliding bearing portion is reduced by pressurizing the second sliding bearing portion in a direction opposite to the applied pressure received by the rotating body. Accordingly, it is possible to provide a sliding bearing that can suppress wear of the first sliding bearing portion that positions the rotating body at a predetermined position, is inexpensive, and can ensure durability without depending on the performance of the material. I can do it.

FIG. 3 is a schematic longitudinal sectional front view of the fixing device according to the first exemplary embodiment in which a middle portion in the longitudinal direction is omitted. (A) is a perspective view of a sliding bearing mechanism portion on the right side of the fixing device, and (b) is a perspective view of a sliding bearing mechanism portion on the left side. It is a disassembled perspective view of a sliding bearing mechanism. FIG. 6 is an explanatory diagram of a driving unit of the fixing device. FIG. 10 is a schematic longitudinal sectional front view of a fixing device according to a second exemplary embodiment in which a middle portion in the longitudinal direction is omitted. It is a disassembled perspective view of a sliding bearing mechanism. 1 is a schematic configuration diagram of an example of an image forming apparatus equipped with a fixing device to which a sliding bearing according to the present invention is applied. (A) is a perspective view of the fixing device according to the first embodiment (showing a state in which the top plate of the apparatus housing is removed), and (b) is a schematic cross-sectional view of the main part of the fixing device. It is a disassembled perspective view of a heating unit.

[Example 1]
(1) Example of Image Forming Apparatus FIG. 6 is a schematic configuration diagram of an example of an image forming apparatus equipped with a fixing device A to which a sliding bearing according to the present invention is applied. The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process.

  Reference numeral 31 denotes a photosensitive drum, which is driven to rotate at a predetermined peripheral speed (process speed) in the clockwise direction indicated by an arrow R31. The surface of the photosensitive drum is uniformly charged to a predetermined polarity and potential by the charging roller 32. The charged surface is subjected to main scanning exposure using a laser beam L which is output from the laser scanner 33 and modulated in accordance with image information. As a result, an electrostatic latent image corresponding to the exposure pattern is formed on the surface of the photosensitive drum.

  The electrostatic latent image is developed as a toner image by the developing device 34. In the transfer nip portion 36 where the toner image is a pressure contact portion between the photosensitive drum 31 and the transfer roller 35, a recording material (paper or the like) introduced into the transfer nip portion 36 at a predetermined control timing from a paper feed portion (not shown). Sheet) are sequentially transferred onto the surface of S.

  The recording material S that is nipped and conveyed by the transfer nip portion 36 and has received the transfer of the toner image is separated from the surface of the photosensitive drum 31 and conveyed to the fixing device A. The recording material S is heated and pressed in the process of being nipped and conveyed at the fixing nip N which is a pressure contact portion between the heating unit 10 of the fixing device A and the pressure roller 1. As a result, the toner image is fixed on the surface of the recording material S as a fixed image. The recording material S that has undergone image fixing is sent out from the fixing device A by the fixing discharge guide 21 and the fixing discharge roller 22 and is discharged out of the image forming apparatus as an image formed product.

  On the other hand, the remaining transfer residual toner is removed (cleaned) by the cleaning device 37 on the surface of the photosensitive drum 31 after separation of the recording material, and is repeatedly used for image formation.

(2) Fixing device A
FIG. 7A is a perspective view of the fixing device A in this embodiment. The fixing device A in this figure shows a state in which the top plate 12B (FIG. 1) of the device housing 12 is removed. FIG. 2B is a schematic cross-sectional view of the main part of the fixing device A. FIG. 1 is a schematic longitudinal sectional front view of the fixing device A in which a part in the longitudinal direction is omitted. 2A is a perspective view of a sliding bearing mechanism portion on the right side of the fixing device A, and FIG. 2B is a perspective view of a sliding bearing mechanism portion on the left side.

  In the fixing device A of this embodiment, the front side is a surface viewed from the recording material inlet side, and the back side is a surface viewed from the opposite side (recording material outlet side). Left and right are left or right when the device is viewed from the front. In the fixing device A of this embodiment, a pressure roller gear 8 as a driving unit is provided on the right side, the right side of the fixing device A is the driving side, and the left side is the non-driving side.

  The fixing device A of the present embodiment is a belt heating that uses a heat-resistant resin or metal overall flexible and low heat capacity cylindrical sleeve (endless belt) 16 as a heating member (fixing member). This is an image heating apparatus of a type and a pressure member driving type.

  Reference numeral 10 denotes a heating unit including the sleeve 16, and reference numeral 1 denotes an elastic pressure roller as a pressure member. The heating unit 10 and the pressure roller 1 are disposed between the left and right side plates 12L and 12R of the apparatus housing (sheet metal frame) 12 so as to be held substantially in parallel in the vertical direction. A fixing nip portion N is formed.

  The pressure roller 1 has a cored bar (shaft part) 1a, a heat-resistant elastic member layer 1b formed concentrically around the cored bar in a roller shape, and a releasable layer 1c covering its outer peripheral surface. doing. In the pressure roller 1, the left end and the right end of the core bar 1a are rotatably supported by left and right slide bearings 23L and 23R, respectively. This sliding bearing will be described in detail in section (3).

  The heating unit 10 is an assembly (assembly) such as a stay holder 25, a heater 26, a sleeve 16 as a fixing member, and left and right flange members 18L and 18R. FIG. 8 is an exploded perspective view of the heating unit 10.

  The stay holder 25 is a member having heat resistance and rigidity, which is long in the left-right direction. In the present embodiment, the stay holder 25 is a member having a substantially semicircular arc shape in cross section. The heater 26 is a low heat capacity heating body in which the entire length of the effective heat generation length region suddenly generates heat when energized. In this embodiment, it is a thin and thin ceramic heater that is long in the left-right direction. The heater 26 is fixedly supported by being fitted into a groove provided along the length on the lower surface side of the stay holder 25. The sleeve 16 is loosely fitted to the stay holder 25 that fixes and supports the heater 26.

  The left and right flange members 18L and 18R are symmetrical heat-resistant resin molded products, and are fitted to the left and right outward extending arm portions 25aL and 25aR of the stay holder 25 to which the heater 26 is attached and the sleeve 16 is fitted. It is worn. The left and right flange members 18L and 18R receive the left and right end surfaces of the sleeve 16 at their opposing surfaces (inner surface side), thereby regulating the movement of the sleeve 16 in the left-right direction (thrust direction). Further, substantially arc-shaped guide convex portions 18 a provided on the respective opposing surfaces are positioned on the inner peripheral surface side of the left and right end portions of the sleeve 16 and serve to retain the left and right end portions of the sleeve 16.

  The left and right side plates 12 </ b> L and 12 </ b> R of the apparatus housing 12 are each provided with a vertical slit portion 12 a having a left-right symmetric shape and having an upper side opening portion. Then, the vertical fitting portions 18b provided on the left and right flange members 18L and 18R are inserted into and engaged with the left and right slit portions 12a from the opening portions on the upper side. Thus, the heating unit 10 is disposed between the left and right side plates 12L and 12R with the heater 26 facing downward on the upper side of the pressure roller 1.

  The slit portion 12a and the fitting portion 18b serve as a guide for sliding the heating unit 10 in the direction toward the pressure roller 1 between the side plates 12L and 12R. Accordingly, the heating unit 10 has a degree of freedom to move in the vertical direction with respect to the side plates 12L and 12R.

  The fixing pressure springs 11L and 11R are contracted between the upper surfaces of the left and right flange members 18L and 18R and the rear surfaces of the left and right portions of the upper surface plate 12B of the apparatus housing 12, respectively. As a result, the left and right flange members 18L and 18R are pressurized with an equal predetermined pressure (fixing pressure) P, respectively.

  By this pressurization, the heater 26 is pressed against the upper surface of the pressure roller 1 through the sleeve 16 against the elastic force of the elastic member layer 1 b of the pressure roller 1. As a result, the elastic member layer 1b of the sleeve 16 and the pressure roller 1 bends along the lower surface of the heater 26, and a fixing nip portion N having a predetermined width is formed between the sleeve 16 and the pressure roller 1 in the recording material conveyance direction a. It is formed.

  A pressure roller gear 8 is disposed concentrically and integrally on one end side of the metal core 1a of the pressure roller 1, that is, on the right end portion in this embodiment. This gear 8 receives a driving force by a driving gear 14 (FIG. 4). In this embodiment, when the driving force is transmitted from the driving gear 14 to the gear 16, the pressure roller 1 is rotationally driven at a predetermined rotational speed in the counterclockwise direction indicated by the arrow R1 in FIG. 7B.

  Along with the rotation of the pressure roller 1, a rotational force acts on the sleeve 16 by a frictional force between the pressure roller 1 and the sleeve 16 on the heating unit 10 side in the fixing nip N. Then, the sleeve 16 is driven to rotate clockwise around the outer periphery of the stay holder 25 in FIG. 7B (pressure member drive type) while sliding with the inner surface thereof in close contact with the lower surface of the heater 26.

  The heater 26 is supplied with power from a power source (not shown) via connectors 27L and 27R (FIG. 1) fitted to the left and right outward extending arm portions 25aL and 25aR of the stay holder 25, respectively. Due to this power supply, the heater 26 has its entire length of the effective heat generation length region rapidly increased in temperature and is adjusted to a predetermined temperature (fixing temperature) by a temperature control system (not shown).

  The recording material carrying the unfixed toner image t in a state where the rotational driving of the pressure roller 1 and the driven rotation of the sleeve 16 are performed and the temperature of the heater 26 rises to a predetermined temperature by energizing the heater 26. S is introduced into the fixing nip portion N (FIG. 7B). When the recording material S is nipped and conveyed through the fixing nip portion N, the unfixed toner image t is heated by the heat of the heater 26 through the sleeve 16 and is fixed as a fixed image by the fixing nip pressure. The recording material S that has passed through the fixing nip N is separated from the outer surface of the sleeve 16 and is sent out from the fixing device A by the fixing discharge guide 21 and the fixing discharge roller 22.

(3) Sliding bearing The shaft portion 1a of the pressure roller 1, which is a rotating body, has both left and right ends thereof rotatably supported by sliding bearings 23L and 23R according to the present invention. 2A is a perspective view of the right sliding bearing mechanism portion, and FIG. 2B is a perspective view of the left sliding bearing mechanism portion. FIG. 3 is an exploded perspective view of the sliding bearing mechanism. Since the left and right sliding bearing mechanisms 23L and 23R have the same configuration that is bilaterally symmetric, the following description will mainly focus on one sliding bearing mechanism.

  The sliding bearing mechanism 23 rotatably supports the shaft portion 1a of the pressure roller 1 as a rotating body that rotates while receiving a load due to the pressure P from a direction orthogonal to the rotation axis direction.

  The sliding bearing mechanism 23 is supported by the side plates 12L and 12R, which are fixed frame members, as the first sliding bearing portion 3, and rotatably supports the shaft portion 1a so as to position the pressure roller 1 at a predetermined position. A sliding bearing.

  Moreover, the sliding bearing mechanism 23 has the sliding bearing which is arrange | positioned as the 2nd sliding bearing part 5 adjacent to the 1st sliding bearing part 3, and supports the axial part 1a rotatably. The second sliding bearing portion 5 is pressurized by the elastic member 6 with a pressing force F2 smaller than the pressing force P in a direction opposite to the pressing direction of the pressing force P.

  That is, the end portion of the metal core (shaft portion) 1 a of the pressure roller 1 is rotatably supported by the first sliding bearing portion 3 and the second sliding bearing portion 5. The heating unit 10 is pressurized with a pressure P toward the pressure roller 1 by a fixing pressure spring 11 (FIG. 1). Accordingly, the pressure roller 1 rotates while receiving a load due to the pressure P from a direction orthogonal to the rotation axis direction.

  The first sliding bearing portions 3 in the left and right sliding bearing mechanisms 23L and 23R are respectively supported by the left and right side plates (fixed frame members) 12L and 12R of the apparatus housing 12, and the pressure roller 1 is placed at a predetermined position. The cored bar 1a is rotatably supported so as to be positioned.

  In this embodiment, the first sliding bearing portion 3 is a U-shaped member whose upper side is opened, and the core metal 1a of the pressure roller 1 can be freely rotated to a predetermined position by the U-shaped shaft support portion. I support it. The first sliding bearing portion 3 has a fitting portion 3a (FIG. 3) on the lower surface side, and the fitting portion 3a is engaged with the edge of the lower end portion of the slit portion 12a of the side plates 12L and 12R. . Thus, the first plain bearing portion 3 is positioned and supported with respect to the side plates 12L and 12R as fixed frame members.

  In the present embodiment, one second sliding bearing portion 5 is disposed adjacent to the first sliding bearing portion 3. The second plain bearing portion 5 is a U-shaped member whose upper side is opened, and rotatably supports the core metal 1a of the pressure roller 1 by a U-shaped shaft support portion. The second plain bearing portion 5 is supported so as to be movable in the same direction as the fixing pressure direction (vertical direction in this embodiment) with respect to the holder member 19 fixedly disposed on the bottom plate 12A of the apparatus housing 12. ing. And it is pressurized with the applied pressure F2 in the direction which opposes the direction which pressurizes the heating unit 10 with the bearing pressurization spring 6 as an elastic member.

  In the present embodiment, the second plain bearing portion 5 has a longitudinal groove portion 5a. The holder member 19 has a vertical ridge 19a in which the vertical groove 5a is fitted and engaged. The second sliding bearing portion 5 is supported by the holder member 19 so as to be movable in the up and down direction, which is the same direction as the fixing and pressing direction, by the fitting engagement between the vertical groove portion 5a and the ridge 19a.

  The bearing pressure spring 6 is contracted between the holder member 19 and the second sliding bearing portion 5, and the second sliding bearing portion 5 is pushed upward and biased by the contraction reaction force. . That is, the core bar 1 a of the pressure roller 1 is pushed upward and biased through the second sliding bearing portion 5.

At this time, the force F1 applied to the first plain bearing portion 3 is:
F1 = P-F2
Thus, the force F1 applied to the first sliding bearing portion 3 can be reduced by offsetting the pressing force F2.

  As the durability progresses, the second sliding bearing portion 5 wears, but since the pressure is applied by the bearing pressurizing spring 6, the effect continues even after the endurance. At this time, by reducing the spring constant of the bearing pressurizing spring 6 sufficiently, the spring pressure drop when the second sliding bearing portion 5 is worn can be minimized. At this time, it is necessary to give the second sliding bearing portion 5 a sufficient thickness in anticipation of wear.

  On the other hand, when the first sliding bearing portion 3 is greatly worn, the positions of the pressure roller 1 and the pressure roller gear 8 are displaced, causing problems such as recording material transportability, image, vibration, and noise. The wear amount after durability of one sliding bearing portion 3 needs to be a predetermined value or less. Therefore, the spring pressure of the bearing pressurizing spring 6 can be appropriately set according to the selected bearing material so that the amount of wear of the first sliding bearing portion 3 until the product lifetime becomes less than an appropriate value. In other words, in the past, there was only a countermeasure for selecting an appropriate material, but in the present invention, the problem of wear can be solved by design requirements.

  Further, as described above, the second sliding bearing portion 5 is allowed to wear to some extent, but at that time, bearing dust is generated. It has been empirically found that if this shaving powder wraps around the sliding portion of the first sliding bearing portion 3, the wear of the first sliding bearing portion 3 is accelerated. Since the wear of the first sliding bearing portion 3 needs to be minimized as described above, it is necessary to prevent the shaving powder from entering the sliding portion of the first sliding bearing portion 3.

  Therefore, in this embodiment, the shielding wall 9 provided in the pressure roller core 1a in a disk shape is disposed between the first sliding bearing portion 3 and the second sliding bearing portion 5, and the second The shaving powder of the sliding bearing portion 5 is prevented from entering the sliding portion of the first sliding bearing portion 3.

  Further, in order to prevent the fallen shaving powder from being scattered in the machine and entering the sliding portion of the first sliding bearing portion 3 and the meshing portion of the gears 8 and 14, the lower direction of the second sliding bearing portion 5 is lowered. A box-shaped shaving powder receiving portion 7 is provided on the side (lower side in the direction of gravity). That is, the shaving powder receiving portion 7 receives the shaving powder dropped from the second sliding bearing portion 5 and prevents scattering of the shaving powder during normal operation and when the apparatus is moved.

  Next, the influence of the driving force for rotating the pressure roller 1 on the pressure received by the bearing will be described with reference to FIGS. When the pressure roller gear 8 is rotationally driven by the drive gear 14, the pressure roller gear 8 receives a driving force corresponding to the torque of the fixing device A. The direction is a direction inclined by a gear pressure angle β with respect to a line orthogonal to a straight line connecting the center of the pressure roller gear 8 and the center of the drive gear 14. Accordingly, the direction of the force received by the pressure roller gear 8 and the pressure roller 1 varies depending on the phase in which the drive gear 14 is arranged with respect to the pressure roller gear 8.

As shown in FIGS. 1 and 4, when the fixing pressure P is downward in the vertical direction, if the angle between the straight line connecting the center of the pressure roller gear 8 and the center of the drive gear 14 and the vertical line is α, the gear The vertical component Py of the driving force Pg is
Py = Pg × sin (α−β)
It becomes.

  In other words, when the drive side (right side) of the pressure roller 1 is driven, it receives a force in the direction of being pushed up by the force of Py in the illustrated gear arrangement. In addition, if the phase in which the drive gear 14 is arranged changes, a pressing force may be received. When a force is applied in the direction in which the driving side of the pressure roller 1 is pushed up, the force applied to the first sliding bearing portion 3 in the right sliding bearing 23R is reduced by the amount of Py. Conversely, when a force is applied in a direction in which the driving side of the pressure roller 1 is pushed down, the force applied to the first sliding bearing portion 3 in the sliding bearing 23R on the right side by the Py force is added.

  On the other hand, the non-driving side (left side) of the pressure roller 1 is not subjected to such a driving force from the gear 8, and therefore, the sliding bearing 23L on this side has a first slip due to the gear driving force. There is no effect on the force applied to the bearing portion 3.

  Therefore, when the same sliding bearing is used for the driving side and the non-driving side, the force received by the first sliding bearing portion 3 differs between the driving side and the non-driving side. When the durability of the first sliding bearing portion 3 at the left and right ends of the pressure roller 1 is different from each other, the wear amount of the bearing is different and the pressure roller 1 is misaligned. This is not preferable because it causes a decrease in transportability.

  In the sliding bearing of the present invention, the spring pressure of the bearing pressurizing spring 6 can be arbitrarily set. Therefore, even when the conditions on the driving side and the non-driving side are different as described above, the bearing pressure springs 6 and 6 'on the driving side and the non-driving side are equalized so that the force applied to the first sliding bearing portion 3 is equalized. The pressure can be changed relatively.

  A dynamic model of the applied pressure at this time is shown in FIG. The fixing pressure is P, the bearing pressure spring pressure is F2 (drive side), F2 ′ (non-drive side), the fixing pressure direction component of the gear driving force is Py, and the force received by the first sliding bearing portion 3 is F1. Then, the equations for the balance of forces on the driving side and the non-driving side are as follows.

Drive side: P = F1 + F2 + Py
Non-driving side: P = F1 + F2 ′
That is, if the spring pressure of the bearing pressure springs 6 and 6 ′ is set so that F2 ′ = F2 + Py, the force F1 received by the first sliding bearing portion 3 can be made equal on the driving side and the non-driving side. .

  As described above, when the sliding bearing according to the first embodiment to which the present invention is applied is used, the force applied to the first sliding bearing portion 3 by pressurizing the second sliding bearing portion 5 with an appropriate pressure. Can be reduced. Accordingly, it is possible to suppress the occurrence of problems such as printing accuracy, image, vibration, and noise while using an inexpensive sliding bearing.

  The wear of the first sliding bearing portion 3 can be reduced by suppressing the shaving powder from the second sliding bearing portion 5 from entering the sliding portion of the first sliding bearing portion 3. That is, it is possible to prevent the shaving powder from the second sliding bearing portion 5 from flowing around the sliding portion of the first sliding bearing portion 3 by the shielding wall 9. It is possible to prevent the wear from accelerating.

  Further, the shaving powder receiving portion 7 provided on the lower side in the vertical direction of the second sliding bearing portion 5 receives the shaving powder that has come out of the second sliding bearing portion 5. As a result, it is possible to prevent the shaving powder from scattering into the machine, and to prevent the shaving powder from entering the meshing portions of the first sliding bearing portion 3 and the gears 8 and 14, and the first sliding bearing portion 3 and the gear 8 can be prevented by the shaving powder. -It can prevent the wear of 14 from accelerating.

[Example 2]
This embodiment is an example of a sliding bearing having a configuration in which two second sliding bearing portions 5 are arranged adjacent to the first sliding bearing portion 3. FIG. 5A is a schematic longitudinal sectional front view of the fixing device A with the middle portion in the longitudinal direction omitted. FIG. 5B is an exploded perspective view of the sliding bearing mechanism in the present embodiment.

  The configuration of the fixing device A in this embodiment is different from the fixing device A of the first embodiment only in the configuration of the left and right sliding bearings 23L and 23R, and the other configurations are the same. The same reference numerals are attached and the description thereof is omitted. Further, since the left and right sliding bearing mechanisms 23L and 23R have the same configuration that is bilaterally symmetric, the following description will be mainly focused on one sliding bearing mechanism.

  In the slide bearing mechanism 23 in the present embodiment, the first slide bearing portion 3 is the same as the first slide bearing portion 3 in the first embodiment. That is, the first sliding bearing portion 3 is a U-shaped member whose upper side is opened, and the core metal 1a of the pressure roller 1 is rotatably supported at a predetermined position by a U-shaped shaft support portion. . The first sliding bearing portion 3 has a fitting portion 3a on the lower surface side, and the fitting portion 3a is engaged with the edge of the lower end portion of the slit portion 12a of the side plates 12L and 12R. Thus, the first plain bearing portion 3 is supported by the side plates 12L and 12R as fixed frame members.

  Two second plain bearing portions 5 (1) and 5 (2) are provided adjacent to the first plain bearing portion 3 on the outer side and the inner side with the first plain bearing portion 3 in the middle. It is arranged. The two second plain bearing portions 5 (1) and 5 (2) of the outer side portion and the inner side portion are U-shaped members that are open on the upper side, and are integrally coupled via a common holder member 19. ing.

  The holder member 19 is provided with a vertical fitting portion 19a, and the vertical fitting portion 19a is engaged with a vertical slit portion 12b provided on the side plates 12L and 12R. Accordingly, the holder member 19 has a degree of freedom to move in the vertical direction with respect to the side plates 12L and 12R. The bearing pressure spring 6 is contracted between the lower surface of the holder member 19 and the lower end surface of the slit portion 12b, and the holder member 19 is pushed upward and biased by the contraction reaction force. That is, the outer and inner second plain bearing portions 5 (1) and 5 (2) are both pushed upward and biased via the holder member 19.

  The first sliding bearing portions 3 in the left and right sliding bearing mechanisms 23L and 23R rotatably support the core metal 1a so as to position the pressure roller 1 at a predetermined position. The two second plain bearing portions 5 (1) and 5 (2) outside and inside the first plain bearing portion 3 rotate the core metal 1a of the pressure roller 1 with a U-shaped shaft support portion. While supporting freely, it pressurizes with the applied pressure F3 in the direction which opposes the direction which pressurizes the heating unit 10 with the bearing pressurization spring 6. FIG.

At this time, the force F1 applied to the first plain bearing portion 3 is:
F1 = P-F3
Thus, the force F1 applied to the first sliding bearing portion 3 can be reduced by offsetting the pressing force F3. Therefore, the sliding bearing mechanisms 23L and 23R in the present embodiment also have the same effects as the sliding bearing mechanism in the first embodiment. The influence of the roller driving force on the bearing reaction force is the same as that described in the first embodiment, and the same measures can be taken.

  In the present embodiment, between the first sliding bearing portion 3 and the outer second sliding bearing portion 5 (1), and between the first sliding bearing portion 3 and the inner second sliding bearing portion 5 (2). ) Are respectively provided at two locations. Further, a box-shaped shaving powder receiving portion 7 for receiving the shaving powder of the second sliding bearing portion 5 is disposed on the holder member 19 and the bottom plate 2A of the apparatus housing.

  As described above, when the bearing according to the second embodiment to which the present invention is applied is used, the second sliding bearing portion 5 is applied to the first sliding bearing portion 3 by pressurizing with the appropriate pressure. The force can be reduced. The wear of the first sliding bearing portion 3 can be reduced by suppressing the shaving powder from the second sliding bearing portion 5 from entering the sliding portion of the first sliding bearing portion 3. Since both the first sliding bearing portion 3 and the second sliding bearing portion 5 are supported by the side plates 12L and 12R, there is an advantage that the above-described effects can be obtained without increasing the size of the device. .

  Here, the sliding bearing according to the present invention is not limited to the bearing means of the pressure roller 1 of the fixing device A of the embodiment, but is a rotating body that rotates while receiving a load due to the pressure P from a direction orthogonal to the rotational axis direction. It can be widely used as a sliding bearing for receiving a shaft portion. For example, it is effective and suitable as a sliding bearing for receiving a shaft of a rotating body in a transport roller in a device that transports paper, such as a printer, a copying machine, and a fax machine, and other various devices and mechanisms.

  23 .. Sliding bearing, 1 .. Rotating body (pressure roller), 1 a .. Shaft, P .. Pressurizing force, 12 .. Fixed frame member, 3. Second sliding bearing part, 6 ... Elastic member, 9 ... Shielding wall, 7 ... Shaving powder receiving part

Claims (4)

A sliding bearing that receives a shaft portion of a rotating body that rotates while receiving a load due to a pressure applied from a direction orthogonal to the rotation axis direction,
A first sliding bearing portion supported by a fixed frame member and rotatably supporting the shaft portion so as to position the rotating body at a predetermined position;
A second sliding bearing portion disposed adjacent to the first sliding bearing portion and rotatably supporting the shaft portion, the direction facing the pressurizing direction of the pressurizing force by an elastic member A second sliding bearing portion pressed with a pressing force smaller than the pressing force;
A sliding bearing characterized by comprising:   The sliding bearing according to claim 1, further comprising a shielding wall between the first sliding bearing portion and the second sliding bearing portion.   The sliding bearing according to claim 1 or 2, further comprising a box-shaped shaving powder receiving portion for receiving bearing shaving powder on a lower side in a vertical direction of the second sliding bearing portion. In a fixing device having a rotating body for conveying a recording material carrying a toner image while applying pressure, and fixing the toner image on the recording material,
A fixing device comprising the sliding bearing according to claim 1 as a bearing of the rotating body.