JP5609060B2 - Power transmission device - Google Patents

Description

  The present invention relates to a power transmission device that transmits a driving force to a cartridge such as a process cartridge.

  Conventionally, in order to transmit a driving force to a process cartridge, a power transmission device composed of a coupling type docking gear has been employed to suppress rotation unevenness.

  For example, as shown in FIG. 11, the process cartridge 80 includes a power transmission device 86 having a docking gear 83 connected to a drive source disposed on the image forming apparatus main body side. The docking gear 83 has an engaging portion 85 that engages with a driving source at the tip, a driving gear 82 that meshes with the driven gear 81 on the outer periphery, and rotates around a fulcrum shaft 84 on which a cover 83a is extrapolated. Supported as possible. The shaft of the driven gear 81 is connected to, for example, a developing roller in the process cartridge 80.

  One end of the fulcrum shaft 84 is fitted to and supported by the support portion 88 of the casing 87, and a screw 83b is attached to the other end. An annular protrusion 89 is provided on the inner peripheral surface of the docking gear 83, and the annular protrusion 89 abuts on the screw 83 b to prevent the docking gear 83 from coming off from the fulcrum shaft 84 in the axial direction.

  However, in the power transmission device 86, since the docking gear 83 is only fitted and supported on the fulcrum shaft 84 supported at one end (cantilever) by the casing 87, the drive gear 82 disposed on the outer periphery of the docking gear 83 is provided. When meshed with the driven gear 81 and receiving an external force, there is a problem that the fulcrum shaft 84 and the docking gear 83 bend. Further, in order to increase the support strength of the support shaft 84, it is necessary to increase the size of the support portion 88.

  On the other hand, in Patent Document 1, a shaft is supported at three points to support a flywheel and a belt that drives the flywheel, and a restriction portion that restricts movement in the axial direction and a position of the bearing are provided on the bearing. There is described a power transmission device that can prevent unnecessary stress from being generated in a bearing by providing a spring means for adjustment.

  However, the power transmission device described in Patent Document 1 has a problem that the structure of the bearing is complicated and the manufacturing cost increases.

JP 2001-51552 A

  The present invention has been made in view of the above-described conventional problems, and provides a power transmission device that can increase the strength when subjected to an external force and can be reduced in size and can reduce the manufacturing cost. Is an issue.

In order to solve the above problems, a power transmission device according to the present invention is provided in a cartridge that is detachable from a main body, and transmits a driving force from the main body to a driven portion in the cartridge, A fulcrum shaft whose end is cantilevered by the casing of the cartridge, and an engagement that is fitted around the fulcrum shaft so as to be rotatable about the fulcrum shaft and engages with the drive unit of the main body And a docking gear having a driving gear engaged with a driven gear coupled to a driven part in the casing,
The docking gear is fitted at two points, a first fitting part on the fixed end side of the fulcrum shaft and a second fitting part on the free end side,
The docking gear is rotatably supported by the casing at a third fitting portion provided in the vicinity of the engaging portion,
The second fitting portion located on the free end side of the fulcrum shaft is located in the vicinity of the third fitting portion of the docking gear, and the third fitting portion is located at the fulcrum than the second fitting portion. It is located on the fixed end side of the shaft .

  With the above configuration, the external force received by the docking gear is transmitted from the first fitting portion and the second fitting portion to the fulcrum shaft, and the fulcrum shaft is supported at both ends by the casing. Therefore, compared with the case where the fulcrum shaft is cantilevered, the strength when the docking gear receives an external force can be increased, and the support portion of the fulcrum shaft can be downsized. Furthermore, since the second fitting portion can be disposed in the vicinity of the third fitting portion and the strength can be increased with a simple configuration, the manufacturing cost of the power transmission device can be reduced.

  It is preferable that the third fitting portion includes a plurality of circular convex portions projecting radially outward from the outer periphery of the docking gear.

  According to the power transmission device of the present invention, the external force received by the docking gear is transmitted from the first fitting portion and the second fitting portion to the fulcrum shaft, and the fulcrum shaft is supported at both ends by the casing. Therefore, compared with the case where the fulcrum shaft is cantilevered, the strength when the docking gear receives an external force can be increased, and the support portion of the fulcrum shaft can be downsized. Furthermore, since the second fitting portion can be disposed in the vicinity of the third fitting portion and the strength can be increased with a simple configuration, the manufacturing cost of the power transmission device can be reduced.

1 is a schematic front view of an image forming apparatus including a process cartridge according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the process cartridge of FIG. 1. FIG. 3 is a perspective view of a power transmission device that drives the process cartridge of FIG. 2 as viewed from the mounting side. FIG. 4 is an enlarged perspective view of a cover disposed at an end portion of the process cartridge in FIG. 3. It is the perspective view which looked at the power transmission device of FIG. 3 from the drawer side. It is an expanded sectional view of the power transmission device of FIG. It is a figure which shows the external force received when the drive gear of FIG. 6 meshes with a driven gear. 6A is a diagram showing the force acting on the fulcrum shaft and the docking gear of FIG. 6 when an external force is received from the driven gear, and FIG. 6B is a diagram showing one point of the fulcrum shaft and the docking gear when the configuration of the present invention is not taken. (C) is a schematic sectional drawing which shows the state which the fulcrum shaft and docking gear of (b) fell down, when the external force acts on the docking gear. It is sectional drawing which shows the modification of the power transmission device of FIG. It is a perspective view which shows the modification of the coupling gear shown in FIG. It is sectional drawing of the power transmission device which employ | adopts the conventional coupling system.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an image forming apparatus 11 which is a tandem color laser printer. The image forming apparatus 11 includes a main body 11a, a process cartridge 12, a transfer unit 13, an exposure unit 14, a paper feed unit 15, and a cleaning unit 16.

  The process cartridges 12 are arranged at four locations along the intermediate transfer belt 18 of the transfer unit 13, and image formation of yellow (Y), magenta (M), cyan (C), and black (Bk) is performed from the cleaning unit 16 side, respectively. As a result, a color image is formed on the surface of the intermediate transfer belt 18.

  The transfer unit 13 bridges the intermediate transfer belt 18 between the pair of support rollers 27 and 28, drives the support roller 27 by a power transmission device (not shown), and drives the intermediate transfer belt 18 in the arrow A direction. The transfer unit 13 is opposed to a primary transfer roller 31 that constitutes a primary transfer portion facing the photosensitive drum 20 and a support roller 27, as typically shown by a yellow photosensitive drum 20. And a secondary transfer roller 33 constituting a secondary transfer portion.

  The exposure unit 14 irradiates the photosensitive drum 20 with a laser beam to form an electrostatic latent image corresponding to image data sent from a personal computer (not shown).

  The sheet feeding unit 15 sequentially conveys the recording medium S accommodated in the sheet feeding cassette 35 and the manual sheet feeding cassette 36 to the secondary transfer unit via the conveyance roller 37. The toner image formed on the intermediate transfer belt 18 is transferred to the recording medium S transported to the secondary transfer unit, and the toner image transferred by the fixing unit 38 is fixed, and then transferred to the discharge tray 39. The

  The cleaning unit 16 can come into contact with and separate from the intermediate transfer belt 18, and collects and cleans toner remaining on the intermediate transfer belt 18 when approaching.

FIG. 2 shows details of the process cartridge 12 according to the present invention.
Each process cartridge 12 includes a charging device 21, a developing device 22, and a cleaning device 23 around the photosensitive drum 20, as typically shown by a yellow process cartridge 12. The photosensitive drum 20 is rotatably disposed in the drum side casing 24.

  The charging device 21 gives a predetermined charge to the surface of the photosensitive drum 20. This surface potential becomes an electrostatic latent image when exposed by the exposure unit 14.

  The developing device 22 includes in the developing-side casing 25 a toner accommodating portion 41 that accommodates toner, a developing roller 42 that supplies toner to the photosensitive drum 20, and a supply roller 43 that supplies toner to the developing roller 42. ing. The developing device 22 supplies toner to the photosensitive drum 20 to develop the electrostatic latent image. A toner cartridge 26 that replenishes toner to the developing device 22 is detachably installed above the developing device 22.

  The cleaning device 23 includes a cleaning blade 23 a that scrapes off the residual toner on the photosensitive drum 20 and a transport roller 23 b that transports the collected toner. After the transfer to the photosensitive drum 20, the cleaning device 23 remains on the surface. Collect and clean the toner.

  FIG. 3 shows the photosensitive drum 20 and the cleaning device 23 which are a part of the process cartridge 12. For convenience of explanation, the arrow B direction in the figure is referred to as a mounting side to the main body 11a, and the opposite direction is referred to as a drawing side from the main body 11a. The process cartridge 12 is mounted on the main body 11a in the direction of the arrow and pulled out in the reverse direction.

  A cover 45, which is a casing for bearing the photosensitive drum 20 and positioning the process cartridge 12 on the main body 11a, is attached to the end of the process cartridge 12 on the mounting side of the main body 11a. As shown in FIG. 4, the cover 45 is integrally formed with a support portion 47 having a through hole 46 that rotatably supports the power transmission device 51 by fitting with a docking gear 52 of the power transmission device 51 described later. ing.

  As shown in FIG. 5, a power transmission device 51 is disposed near the cover 45 of the process cartridge 12. The power transmission device 51 includes a fulcrum shaft 53 provided side by side on the photosensitive drum 20, and a docking gear 52 that is externally fitted to the fulcrum shaft 53 and transmits driving in a coupling manner.

  The fulcrum shaft 53 is made of metal, and as shown in FIG. 6, the fixed end portion 54 is fitted and supported by the support portion 24a of the drum-side casing 24, extends in a direction parallel to the axis of the photosensitive drum 20, and has a free end. It is an end 55. In the fulcrum shaft 53, a first fitting portion 63 is formed in the vicinity of the fixed end portion 54, and a second fitting portion 64 having a smaller diameter than the first fitting portion 63 is formed in the vicinity of the free end portion 55.

  The docking gear 52 is made of resin, and includes a first cylindrical portion 58 that is extrapolated to the fulcrum shaft 53 and a second cylinder that has a larger diameter than the first cylindrical portion 58 provided at the mounting side end of the first cylindrical portion 58. Part 59, an engagement part 59a composed of, for example, three teeth provided in the circumferential direction at the mounting side end of the second cylindrical part 59, and the inner periphery of the mounting side end of the first cylindrical part 58 It consists of the annular protrusion part 60 which protrudes toward a center from a surface.

  A drive gear 61 that meshes with the driven gear 71 in the process cartridge is formed on the outer periphery of the drawing side end of the first cylindrical portion 58. The shaft of the driven gear 71 is connected to, for example, the developing roller 42 and / or the supply roller 43 which are driven parts in the process cartridge.

  A third fitting portion 65 that fits into the through hole 46 of the support portion 47 is formed on the outer peripheral surface of the second cylindrical portion 59, and the docking gear 52 is rotatably supported. The engaging portion 59a of the second cylindrical portion 59 is connected to a drive source provided in the main body 11a.

  In addition, the docking gear 52 is configured such that the first fitting portion 63 of the fulcrum shaft 53 and the pull-out side end portion of the first cylindrical portion 58 are fitted, and the second fitting portion 64 of the fulcrum shaft 53 and the docking gear 52 are annular. The protrusion 60 is fitted and supported at two points, and rotates around the fulcrum shaft 53.

Hereinafter, the operation of the power transmission device 51 will be described.
When the process cartridge 12 is mounted on the main body 11a, the engaging portion 59 of the docking gear 52 is connected to the drive source of the main body 11a. The docking gear 52 rotates by the driving force from the driving source on the main body side, and the driving force is transmitted from the driving gear 61 of the docking gear 52 to the developing roller 42 and / or the supply roller 43 via the driven gear 71.

  When the driving force is transmitted to the driven gear 71 via the driving gear 61, as shown in FIG. 7, when the driving gear 61 rotates in the direction of the arrow in the figure, the tangential force Ft is in the X-axis direction, and the Y-axis direction is in the Y-axis direction. Is a radial force Fr, and an axial force Fx acts in the Z-axis direction. When these forces act on the drive gear 61, the external force Fx shown in FIG.

  However, the docking gear 52 is fitted and supported at two points by the first fitting portion 63 and the second fitting portion 64 of the fulcrum shaft 53. The external force Fx is transmitted from the first fitting portion 63 to the casing 24 through the fixed end portion 54, while from the first fitting portion 63 to the second fitting portion 64, the annular projecting portion 60, and the third fitting portion 65. It is transmitted to the support part 47 through. Therefore, the force Fa received by the fulcrum shaft 53 from the docking gear 52 is balanced with the reaction force Fb received from the casing 24 and the reaction force Fc received from the docking gear 52, so that the fulcrum shaft 53 is in a doubly supported state. As a result, the support strength between the fulcrum shaft 53 and the docking gear 52 can be increased and integrated, and can be prevented from falling down as in the prior art.

  As shown in FIG. 8B, the fulcrum shaft 53 is short, and one end portion of the docking gear 52 is fitted to the fulcrum shaft 53 supported by the support portion 24a, and the other end portion is the support portion 47. Is supported by In this case, when the external force Fx generated when the drive gear 61 meshes with the driven gear 71 acts on the docking gear 52, the docking gear 52 and the fulcrum shaft 53 are only fitted at one point, so FIG. As shown in c), the docking gear 52 and the fulcrum shaft 53 may fall down.

  In this embodiment, the fulcrum shaft 53 is supported at both ends as described above. Therefore, the support strength can be increased compared to the case where the fulcrum shaft 53 is supported at one point, and the strength when the docking gear 52 receives an external force can be increased without increasing the size of the support portion 24a. Furthermore, since the strength can be increased with a simple configuration using existing parts, the manufacturing cost of the power transmission device 51 can be reduced.

  Further, since the second fitting portion 64 of the fulcrum shaft 53 is located in the vicinity of the third fitting portion 65 of the docking gear 83, the strength when the docking gear 52 receives an external force can be further increased. .

The present invention is not limited to the above embodiment, and various modifications can be made.
In the above-described embodiment, the third fitting portion 65 that supports the docking gear 52 is located on the free end side of the second fitting portion 64 of the fulcrum shaft 53. It is also possible to adopt a configuration in which the same position is used. Thereby, the strength when the docking gear 52 receives an external force can be further increased. Alternatively, the third fitting portion 65 may be positioned on the fixed end side with respect to the second fitting portion 64.

  In addition, the support portion 47 that rotatably supports the drawing-side end portion 54 of the fulcrum shaft 53 is provided in the drum-side casing 24 in the embodiment. However, the present invention is not limited to this as long as the support strength can be ensured. For example, as shown in FIG. 9, a support portion 25a provided in the development side casing 25 may be adopted.

  Regarding the third fitting portion 65 with the support portion 47 of the docking gear 52, a circular convex portion 66 is partially formed on the outer periphery of the cylindrical portion 58 so as to protrude outward in the radial direction as shown in FIG. Even if this mode is adopted, the same effect can be obtained. It is preferable that the circular convex portion 66 is provided on the fixed end side of the fulcrum shaft 54 with respect to the annular projecting portion 60 and fitted with the fitting portion 12 a provided on the casing of the process cartridge 12 instead of the cover 47.

11a body 12 process cartridge 20 photosensitive drum 22 developing device 42 developing roller (driven portion)
43 Supply roller (driven part)
45 Cover (casing)
47 support part 51 power transmission device 52 docking gear 53 fulcrum shaft 61 drive gear 63 first fitting part 64 second fitting part 65 third fitting part

Claims (2)

A power transmission device that is provided in a cartridge that is detachable from a main body, and that transmits a driving force from the main body to a driven portion in the cartridge, wherein one end is cantilevered by a casing of the cartridge An engagement portion that is extrapolated and fitted to the fulcrum shaft, is rotatably provided about the fulcrum shaft, and is engaged with the drive portion of the main body, and is connected to the driven portion in the casing In a power transmission device comprising a docking gear having a drive gear engaged with a gear,
The docking gear is fitted at two points, a first fitting part on the fixed end side of the fulcrum shaft and a second fitting part on the free end side,
The docking gear is rotatably supported by the casing at a third fitting portion provided in the vicinity of the engaging portion,
The second fitting portion located on the free end side of the fulcrum shaft is located in the vicinity of the third fitting portion of the docking gear, and the third fitting portion is located at the fulcrum than the second fitting portion. A power transmission device located on a fixed end side of a shaft . 2. The power transmission device according to claim 1, wherein the third fitting portion includes a plurality of circular convex portions projecting radially outward from an outer periphery of the docking gear.

Images