JP2012203068A - Sliding bearing, fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rotatably support a rotating body that receives a load in a fixed radial direction such as a heating roll, with a sliding bearing, while preventing wear of the bearing and reducing rotation torque of the rotating body.SOLUTION: On a contact surface 38 formed on an inner diameter of a curved sliding bearing 32, in an upstream contact part 41 on the upstream of a load receiving part 40, which receives a load in a rotating body radial direction, in the rotation direction of the rotating body, a recess 43 is formed in the center in the rotating body axial direction. The contact length in the rotating body axial direction of the upstream contact part 41 is shorter than that of the load receiving part 40. The contact length in the rotating body axial direction of the upstream contact part 41 is reduced toward the upstream in the rotating body rotation direction. The contact length in the rotating body axial direction of a downstream contact part 42 on the downstream of the load receiving part 40 in the rotating body rotation direction is larger than the contact length in the rotating body axial direction of the upstream contact part 41. The contact length in the rotating body axial direction of the downstream contact part 42 is reduced toward the downstream of the rotating body rotation direction.

Description

  The present invention relates to a sliding bearing, a fixing device, and an image forming apparatus.

In an image forming apparatus such as an electrophotographic copying machine, a toner image formed on a recording medium is heat-fixed on the recording medium by a fixing device. At the time of heat fixing, the recording medium on which the toner image is formed is pressed against the heating roll with a constant load by a pressure member. Examples of the support member that rotatably supports the heating roll include the following.
In the following Patent Document 1, ball bearings are fitted on the outer peripheral surfaces of both ends of the heating roll, and the heating roll is supported by the side frame via each of the ball bearings. Grooves are formed on the outer peripheral surfaces of both ends of the heating roll over the entire circumference, and the grooves are filled with heat-resistant grease.

Further, in Patent Document 2 below, a circumferential groove having an arc-shaped cross section with a radius of 13 mm is formed on the contact surface of the heating roll with the bearing by drawing a cylindrical metal, and a lubricant holding portion at the time of initial assembly of the bearing is provided. I try to double up.
Further, in Patent Document 3 below, a slit-like groove deeper than the pitch circle of the gear is provided along the circumferential direction on the outer peripheral surface of the heating roll driving gear, and lubricating oil is stored in the slit-like groove. As a result, lubricating oil is supplied to the gears.

  Further, in Patent Document 4 below, a roll shaft of a pressure roll that presses a recording medium against a heating roll is rotatably supported by a bearing, and an oil groove in the rotation direction of the roll shaft and the rotation direction in the roll shaft contact surface of the bearing. An oil groove is formed in a direction that intersects with.

JP 2003-186338 A JP 2002-156855 A JP-A-5-141504 JP 2000-242113 A

  An object of the present invention is to provide rotational torque of a rotating body while suppressing wear of the bearing when a rotating body having a circular cross section perpendicular to the axis that receives a load in the radial direction is rotatably supported by a sliding bearing such as a heating roll. It is to reduce.

The invention according to claim 1 is a load receiving portion that receives a load that contacts the outer peripheral surface of the rotating body and acts in a radial direction of the rotating body, and the upstream side in the rotational direction of the rotating body from the load receiving portion. And a first contact portion that is in contact with the rotating body and has a contact length in the axial direction of the rotating body smaller than that of the load receiving portion.
The invention according to claim 2 is the plain bearing according to claim 1, wherein the first contact portion has a contact length in the rotating body axial direction that is shorter toward the upstream side in the rotating direction of the rotating body.

According to a third aspect of the present invention, the rotating body is in contact with the rotating body downstream of the load receiving portion in the rotating direction, and the contact length in the rotating body axial direction is longer than that of the first contact portion. It is a sliding bearing of Claim 1 or 2 provided with the 2nd contact part.
The invention according to claim 4 is the plain bearing according to claim 3, wherein the second contact portion has a contact length in the rotating body axial direction that is smaller toward the downstream side in the rotating direction of the rotating body.

  According to a fifth aspect of the present invention, there is provided a heating roll as the rotating body, a pressure member that presses a recording medium against the heating roll, a heating roll support member that supports the heating roll, and the pressure member. A pressure member supporting member to be supported; and a coil spring that applies a load between the pressure member and the heating roll by pulling or pressing the heating roll support member and the pressure member supporting member. Fixing device.

  According to a sixth aspect of the present invention, there is provided an image forming portion that forms an image on a recording medium by an electrophotographic method, and the fixing device according to the fifth aspect that fixes a formed image on the recording medium. Image forming apparatus.

According to the first aspect of the present invention, the rotational torque of the rotating body can be reduced while suppressing the wear of the bearing as compared with the case where the present configuration is not provided.
According to invention of Claim 2, compared with the case where it does not have this structure, the rotational torque of a rotary body can be reduced.
According to the third aspect of the present invention, the wear of the bearing can be suppressed as compared with the case where this configuration is not provided.

According to invention of Claim 4, compared with the case where it does not have this structure, the rotational torque of a rotary body can be reduced.
According to invention of Claim 5, compared with the case where this structure is not provided, the rotational torque of a heating roll can be reduced, suppressing abrasion of a bearing.
According to invention of Claim 6, compared with the case where it does not have this structure, the rotational torque of a heating roll can be reduced, suppressing abrasion of a bearing.

1 is a schematic configuration diagram illustrating an embodiment of a sliding bearing, a fixing device, and an image forming apparatus of the present invention. FIG. 2 is a perspective view of a fixing device of the image forming apparatus in FIG. 1. FIG. 3 is an assembly explanatory diagram of the fixing device of FIG. 2. It is a perspective view which shows 1st Embodiment of the sliding bearing used for the fixing device of FIG. FIG. 3 is a front view of the fixing device in FIG. 2. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is a perspective view which shows 2nd Embodiment of the sliding bearing used for the fixing device of FIG. It is a perspective view which shows 3rd Embodiment of the sliding bearing used for the fixing device of FIG.

Hereinafter, embodiments of the slide bearing, the fixing device, and the image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of a slide bearing, a fixing device, and an image forming apparatus of the present invention. The image forming apparatus of this embodiment includes a main body 1 in which each component is housed. Inside the main body 1, a storage unit 3 that stores a recording medium 2 such as paper, an image forming unit 4 that forms an image on the recording medium 2, and the recording medium 2 from the storage unit 3 to the image forming unit 4. A transport unit 5 for transport and a control unit 6 for controlling the operation of each unit of the image forming unit 4 are provided. In addition, a discharge unit 7 that discharges the recording medium 2 on which an image is formed by the image forming unit 4 is provided on the upper portion of the main body 1.

  The image forming unit 4 includes image forming units 8Y, 8M, 8C, and 8K (hereinafter referred to as 8Y to 8Y) that respectively form yellow (Y), magenta (M), cyan (C), and black (K) toner images. 8K), an intermediate transfer belt 9 to which the toner images formed by the image forming units 8Y to 8K are transferred, and a toner image formed by the image forming units 8Y to 8K to the intermediate transfer belt 9. A transfer roll 10 and a second transfer roll 11 that transfers the toner image transferred to the intermediate transfer belt 9 by the first transfer roll 10 to the recording medium 2 are provided. The configuration of the image forming unit 4 is not limited to the above, and other configurations may be used as long as they form an image on the recording medium 2.

  The image forming units 8 </ b> Y to 8 </ b> K are arranged side by side at the center in the vertical direction of the main body 1 while being inclined in the same direction with respect to the horizontal direction. Each of the image forming units 8Y to 8K includes a photoreceptor 12 that rotates in one direction, for example, clockwise in FIG. Around each photoreceptor 12, a charging roll 13 as an example of a charging device for charging the photoreceptor 12 and a photoreceptor 12 charged by the charging roll 13 are exposed in order from the upstream side in the rotation direction of the photoreceptor 12. The exposure device 14 that forms an electrostatic latent image on the photoconductor 12, the developing device 15 that develops the electrostatic latent image formed on the photoconductor 12 by the exposure device 14 to form a toner image, and the photoconductor 12 Then, a removing member 16 for removing the toner remaining on the photoreceptor 12 is provided.

  The exposure device 14 forms an electrostatic latent image based on the image signal sent from the control unit 6. Examples of the image signal sent from the control unit 6 include an image signal acquired by the control 6 from an external device. Further, the developing device 15 includes a toner supply body 15a that supplies toner to the photoconductor 12, and a plurality of transport members 15b that transport the toner supplied to the toner supply body 15a while stirring.

  The intermediate transfer belt 9 is formed in an annular shape and is disposed above the image forming units 8Y to 8K. The intermediate transfer belt 9 is wound around two winding rolls 17. By rotating and driving one of the two winding rolls 17, the intermediate transfer belt 9 circulates (rotates) in one direction, for example, counterclockwise in FIG. 1 while contacting the photoconductor 12. It is like that. Note that the winding roll 17 on the right side of the figure is also a counter roll of the second transfer roll 11.

  The first transfer roll 10 is disposed to face the photoconductor 12 with the intermediate transfer belt 9 interposed therebetween. A space between the first transfer roll 10 and the photoconductor 12 is a first transfer position where the toner image formed on the photoconductor 12 is transferred to the intermediate transfer belt 9. Further, as described above, the first transfer roll 11 is disposed to face the winding roll 17 on the right side of the drawing with the intermediate transfer belt 9 interposed therebetween. Between the second transfer roll 11 and the right-hand winding roll 17 in the drawing is a second transfer position where the toner image transferred to the intermediate transfer belt 9 is transferred to the recording medium 2.

The transport unit 5 is disposed along the transport path 19, a delivery roll 18 that sends out the recording medium 2 accommodated in the storage unit 3, a transport path 19 that transports the recording medium 2 that is sent out by the delivery roll 18, and the transport path 19. Thus, a plurality of transport rolls 20 are provided for transporting the recording medium 2 fed by the feed roll 18 to the second transfer position.
A fixing device 21 that fixes the toner image transferred to the recording medium 2 by the second transfer roll 11 on the recording medium 2 as an example of a conveying device that conveys the recording medium 2 downstream of the second transfer position in the conveying direction. Is provided. The fixing device 21 is provided with a discharge roll 22 that discharges the recording medium 2 on which the toner image is fixed to the discharge unit 7. In addition, the fixing device 21 includes a fixing device main body 23 in which each component is housed, a heating roll 24 as an example of a rotating body that heats the toner image transferred to the recording medium 2, and recording on the heating roll 24. A pressure belt 25 as an example of a pressure member that presses the medium 2 is provided. The heating roll 24 is provided with an elastic layer on the surface of a metal cylindrical tube. The pressure belt 25 is provided with an endless cylindrical member, and a nip portion is formed by pressing the cylindrical member against the heating roll 24 from the inside, and the recording medium 2 is applied to the heating roll 24 with a load set in advance at the nip portion. Press. As a result, the toner image on the recording medium 2 is heated and fixed to form a fixed image.

  In this image forming apparatus, the recording medium 2 sent out from the container 3 by the sending roll 18 is sent to the second transfer position by the plurality of transport rolls 20. On the other hand, in the image forming units 8 </ b> Y to 8 </ b> K, the photosensitive member 12 charged by the charging roll 13 is exposed by the exposure device 14, and an electrostatic latent image is formed on the photosensitive member 12. The electrostatic latent image is developed by the developing device 15, and a toner image is formed on the photoreceptor 12. The toner images formed on the photoreceptor 12 by the image forming units 8Y to 8K are superimposed on the intermediate transfer belt 9 at the first transfer position, and the color toner images are transferred to the intermediate transfer belt 9. The color toner image on the intermediate transfer belt 9 is transferred to the recording medium 2 at the second transfer position. The color toner image transferred to the recording medium 2 is heated and fixed at the nip portion of the heating roll 24 and the pressure belt 25 of the fixing device 21, and the recording medium 2 on which the color fixed image is fixed is discharged by the discharge roll 22. 7 is discharged.

  FIG. 2 shows details of the heating roll 24 and the pressure belt 25 accommodated in the fixing device main body 23 of the fixing device 21 of the image forming apparatus of this embodiment, and FIG. 3 shows an assembly procedure thereof. The heating roll 24 is rotatably supported by a heating roll support member 26, and the pressure belt 25 is supported by a pressure member support member 27. The heating roll support member 26 includes a side plate member 28 that rotatably supports both axial ends of the heating roll 24 and a connecting member 29 that connects the two side plate members 28. The pressure member support member 27 is a side plate member of the pressure belt 25. Reference numeral 30 in the drawing is a gear mechanism that transmits the rotational force of a rotational drive source (not shown) to the heating roller 24.

  The pressure plate support member 27, which is the side plate member of the heating roll support member 26 and the pressure belt 25, is connected to, for example, the heating roll 24 and the pressure belt 25 by a pin member 31 in the lower part of FIGS. It is connected so as to be rotatable in the direction of approaching or moving away. The side plate member 28 of the heating roll support member 26 is formed with a depression having an arc cross-section projecting downward in FIGS. 2 and 3, and an arcuate slide bearing 32 having a contact surface having an arc cross-section attached to the depression. Yes. A heating roll 24 is mounted above the sliding bearing 32 in the figure, and the outer peripheral surface of the heating roll 24 is supported by the sliding bearing 32.

  The pressure belt 25 includes an endless cylindrical member 33, a pressure member 34 that is inserted and disposed on the heating roll 24 side inside the cylindrical member 33, and is long in the axial direction of the cylindrical member 33, and the cylindrical member 33. And an L-shaped plate body 35 that is long in the axial direction of the cylindrical member 33 combined in a direction orthogonal to the pressure body 34, and the pressure body 34 and the plate body 35 are cylindrical. After being inserted into the member 33, a lid body 36 is provided which is attached to the pressure body 34 and the plate body 35 and covers both ends of the cylindrical member 33 in the axial direction. The pressure body 34 has a groove into which the plate body 35 is inserted, and the pressure body 34 and the plate body 35 are combined by inserting the plate body 35 into the groove. The lid body 36 also has grooves into which the pressure body 34 and the plate body 35 are inserted. The pressure body 34 and the plate body 35 are inserted into the grooves, respectively. The plate body 35 is combined.

  The lid 36 of the pressure belt 25 is attached to a predetermined portion of the pressure member support member 27. The pressure member support member 27 is formed with grooves into which both end portions in the longitudinal direction of the plate body 35 are inserted, and both end portions in the longitudinal direction of the plate body 35 are inserted into the grooves. Accordingly, the lid body 36, the pressure body 34, and the plate body 35 of the pressure belt 25 do not rotate, and only the cylindrical member 33 can rotate. When the pressure belt 25 is pressed against the heating roll 24, the pressure body 34 reinforced by the plate body 35 presses and presses the cylindrical member 33 against the surface of the heating roll 24. The pressure member 34 bends the elastic layer of the heating roll 24 via the cylindrical member 33, thereby forming the nip portion described above with the heating roll 24. A cylindrical contact member having a portion corresponding to the pressure body 34 cut out may be interposed between the cylindrical member 33 and the pressure body 34 and the plate body 35.

  One end of a coil spring 37 is attached to each of the upper ends of the two side plate members 28 of the heating roll support member 26, and the two pressure member support members 27 that are side plate members of the pressure belt 25 are attached. The other end portion of the coil spring 37 is attached to each of the upper end portions. Therefore, the heating roll support member 26 and the pressure member support member 27 are attracted by the elastic force of the coil spring 37, and the heating roll 24 and the pressure belt 25 are pressurized with a preset load. As a result, a nip portion is formed between the heating roll 24 and the pressure belt 25.

  FIG. 4 shows a first embodiment of a sliding bearing 32 interposed between the heating roll support member 26 and the heating roll 24. The slide bearing 32 is formed in an arc shape so as to fit into a recess in the arc cross section of the side plate member 28 of the heating roll support member 26, and has an arc cross section in contact with the outer peripheral surface of the heating roll 24 on the inner diameter side. A contact surface 38 is formed. A groove 39 into which the side plate member 28 of the heating roll support member 26 is inserted is formed on the outer side of the arcuate slide bearing 32.

  FIG. 5 shows a front view of the fixing device 21 of FIG. An arrow R in the figure is the rotation direction of the heating roll 24 that is a rotating body. Further, an arrow P in the figure is a load direction to the heating roll 24 by the pressure belt 25, strictly speaking, the pressure body 34. The load applied to the heating roll 24 is directly applied to the sliding bearing 32. That is, the sliding bearing 32 is subjected to a load in a certain radial direction of the rotating body. Of the contact surface 38 of the sliding bearing 32, a portion where this load is applied becomes a load receiving portion 40.

  In the sliding bearing 32 of FIG. 4, the left side of the load receiving portion 40 in the drawing is the upstream side in the rotation direction of the heating roll 24 that is a rotating body, and the right side in the drawing is the downstream side in the rotation direction of the heating roll 24. It is. Therefore, the contact surface 38 on the upstream side in the rotation direction of the heating roll 24 from the load receiving portion 40 is referred to as an upstream contact portion 41, and the contact surface 38 on the downstream side in the rotation direction is referred to as a downstream contact portion 42. In the present embodiment, the concave portion 43 is formed in the heating roll 24 of the contact surface 38 of the upstream contact portion 41, that is, in the central portion in the rotating body axial direction, and as a result, the heating roll 24 axial contact length of the upstream contact portion 41. The length is smaller than the contact length in the axial direction of the heating roll 24 of the load receiving portion 40. Furthermore, in this embodiment, the heating roll 24 axial direction length of the said recessed part 43 is enlarged toward the heating roll 24 rotation direction upstream, As a result, the heating roll 24 axial direction length of the contact surface 38 of the upstream contact part 41 is increased. The heating roll 24 is made smaller toward the upstream side in the rotation direction. 6 shows a cross section taken along the line AA of FIG. 5, that is, a cross section of the upstream contact portion 41 in the rotating direction of the heating roll 24, and FIG. 7 shows a cross section taken along the line BB of FIG. 41 shows a cross section of the downstream portion of the heating roll 24 in the rotation direction, and FIG. 8 shows a CC cross section of FIG.

  In the sliding bearing 32, when the same load is applied, the larger the axial contact length of the rotating body to be supported, the smaller the pressure becomes. Therefore, the sliding bearing 32 is not easily worn, but the contact resistance, that is, the frictional force increases. High rotational torque. On the other hand, when the same load is applied, the smaller the axial contact length of the rotating body to be supported, the smaller the contact resistance, that is, the frictional force. Cheap. Further, when a load is applied in a constant radial direction of the rotating body, a load due to the rotational inertia of the rotating body acts on the contact surface 38 of the sliding bearing 32 on the downstream side in the rotation direction of the heating roll 24 from the load receiving portion 40. To do. Further, when a load is acting in a certain radial direction of the rotating body, the load is larger on the contact surface 38 of the sliding bearing 32 as it is closer to the load receiving portion 40.

Accordingly, in the present embodiment, the contact length of the load bearing unit 40 in the rotating body axial direction of the contact surface 38 of the slide bearing 32 is increased, and the upstream contact unit on the upstream side in the rotation direction of the heating roll 24 from the load receiving unit 40. 41, the rotating body axial direction contact length of 41 is made smaller, and the rotating body axial direction contact length of the upstream contact portion 41 is made smaller toward the upstream side of the heating roll 24 in the rotational direction.
FIG. 9 shows a second embodiment of the sliding bearing 32 interposed between the heating roll support member 26 and the heating roll 24. The slide bearing 32 is similar to the slide bearing 32 of the first embodiment shown in FIG. 4, and the same reference numerals are given to the same components, and detailed description thereof is omitted. In the sliding bearing 32 of the present embodiment, the length of the load receiving unit 40 in the axial direction of the heating roll 24 is increased to the full length of the sliding bearing 32 in the axial direction of the heating roll 24 as in the first embodiment. On the other hand, in the upstream contact portion 41 corresponding to the left side of the figure, the concave portions 43 are formed at both ends of the contact surface 38 in the axial direction of the heating roll 24 so that the contact length in the axial direction of the heating roll 24 is increased. The contact length in the axial direction of the roll 24 is made smaller. The length of the recess 43 in the axial direction of the heating roll 24 is constant. Further, also in the downstream contact portion 42 corresponding to the right side of the figure, a concave portion 43 is formed in the central portion of the contact surface 38 in the axial direction of the heating roll 24 so that the contact length in the axial direction of the heating roll 24 is determined by the heating roll 24 of the load receiving portion 40. It is smaller than the axial contact length. The length of the recess 43 in the axial direction of the heating roll 24 is also constant. The contact length of the contact surface 38 of the downstream contact portion 42 in the axial direction of the heating roll 24 is greater than the contact length of the contact surface 38 of the upstream contact portion 41 in the axial direction of the heating roll 24.

  FIG. 10 shows a third embodiment of a sliding bearing 32 interposed between the heating roll support member 26 and the heating roll 24. The slide bearing 32 is similar to the slide bearing 32 of the first embodiment of FIG. 4 and the slide bearing 32 of the second embodiment of FIG. Detailed description is omitted. In the sliding bearing 32 of the present embodiment, as in the second embodiment, in the upstream contact portion 41 corresponding to the left side of the figure, the concave portions 43 are formed at both ends of the contact surface 38 in the axial direction of the heating roll 24 and heated. The contact length in the axial direction of the roll 24 is made smaller than the contact length in the axial direction of the heating roll 24 of the load receiving portion 40. The length of the recess 43 in the axial direction of the heating roll 24 is constant. Further, also in the downstream contact portion 42 corresponding to the right side of the drawing, a concave portion 43 is formed in the central portion of the contact surface 38 in the axial direction of the heating roll 24. The concave portion 43 is also extended to the load receiving portion 40, but the length of the concave portion 43 in the axial direction of the heating roll 24 is larger toward the downstream side in the rotation direction of the heating roll 24. Is the largest of all the contact surfaces 38, and the contact length 38 of the downstream contact portion 42 in the axial direction of the heating roll 24 is larger than the contact length of the contact surface 38 of the upstream contact portion 41 in the axial direction of the heating roll 24. large.

The pressure member for pressing the recording medium 2 against the heating roll 24 is not limited to the pressure belt 25, and a pressure member used in an image forming apparatus such as an existing electrophotographic copying machine can be used. .
In addition to the fixing device of the image forming apparatus, the sliding bearing can be applied to various sliding bearings in which a load acts in a constant radial direction of the rotating body.

DESCRIPTION OF SYMBOLS 1 Main body 2 Recording medium 3 Accommodating part 4 Image forming part 5 Conveying part 6 Control part 7 Ejecting part 8Y, 8M, 8C, 8K Image forming unit 9 Intermediate transfer belt 10 First transfer roll 11 Second transfer roll 12 Photoconductor 13 Charging Roll 14 Exposure device 15 Developing device 16 Removal member 17 Roll roll 18 Delivery roll 19 Transport path 20 Transport roll 21 Fixing device 22 Discharge roll 23 Fixing device body 24 Heating roll 25 Pressure belt 26 Heating roll support member 27 Pressure member support Member 28 Side plate member 29 Connecting member 30 Gear mechanism 31 Pin member 32 Slide bearing 33 Cylindrical member 34 Pressurizing body 35 Plate body 36 Cover body 37 Coil spring 38 Contact surface 39 Groove 40 Load receiving portion 41 Upstream contact portion 42 Downstream contact portion 43 Recess

Claims (6)

A load receiving portion that receives a load that contacts the outer peripheral surface of the rotating body and acts in the radial direction of the rotating body;
A first contact portion that contacts the rotating body upstream of the load receiving portion in the rotational direction of the rotating body, and has a contact length in the rotating body axial direction smaller than the load receiving portion;
Sliding bearing with.   The sliding bearing according to claim 1, wherein the contact portion has a contact length in a rotating body axial direction that is smaller toward an upstream side in a rotating direction of the rotating body.   2. A second contact portion that is in contact with the rotating body at a downstream side in the rotation direction of the rotating body with respect to the load receiving portion and has a contact length in the rotating body axial direction larger than that of the first contact portion. Or the plain bearing of 2.   The slide bearing according to claim 3, wherein the second contact portion has a contact length in a rotating body axial direction that is smaller toward a downstream side of the rotating body in a rotating direction. A heating roll as the rotating body;
A pressure member that presses the recording medium against the heating roll;
A heating roll support member for supporting the heating roll;
A pressure member support member for supporting the pressure member;
A coil spring that draws or presses the heating roll support member and the pressure member support member to apply a load between the pressure member and the heating roll;
A fixing device provided with An image forming unit that forms an image on a recording medium by an electrophotographic method;
The fixing device according to claim 5, wherein the image formed on the recording medium is fixed.
An image forming apparatus.

Images