JP2012229723A - Transmission device and image forming apparatus including the same - Google Patents

Abstract

When a polygonal shaft is fixed to a rotating member, it is possible to accurately prevent rotation and to prevent the shaft from coming loose.
A transmission device according to the present invention includes a rotating member having a mounting hole in a center of rotation, and a polygonal shaft that is fitted into the mounting hole of the rotating member by press fitting. . On the inner peripheral surface of the mounting hole 67 in the rotating member 62, there are a plurality of inward projections 71 arranged in the circumferential direction. In a state where the polygon shaft 61 is fitted in the mounting hole 67 of the rotating member 62, the inwardly protruding portions 71 are brought into contact with the outer peripheral flat surface 75 of the polygon shaft 61.
[Selection] Figure 5

Description

  The present invention relates to a transmission device that transmits rotational power by a rotating member such as a gear or a roller and a polygonal shaft that is supported by the rotating member, and an image forming apparatus that includes the transmission device. The image forming apparatus includes various apparatuses such as a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions in combination.

  2. Description of the Related Art Conventionally, transmission devices that transmit rotational power using a rotating member such as a gear or a roller and a rotating shaft that supports the rotating member have been used in various technical fields. For example, in an image forming apparatus employing an electrophotographic system, a transmission device is used to rotationally drive a photosensitive drum, a developing roller, a registration roller, and the like (see, for example, Patent Documents 1 and 2).

  By the way, in order to fix the rotating member to the rotating shaft, it is necessary to appropriately prevent rotation and retain. When the rotary shaft is a round shaft, the following configuration is generally used. That is, in order to prevent rotation, a non-circular portion is formed in the round shaft by D-cut processing or the like, while a non-circular hole corresponding to the non-circular portion is formed in the rotating member, and the non-circular portion of the round shaft is formed. It fits into a non-circular hole in the rotating member. And a round shaft is fixed to a rotating member with an E ring or a screw in order to prevent it from coming off.

  On the other hand, examples of the rotation axis other than the round axis include a polygonal axis such as a hexagonal axis. In order to fix the polygon shaft to the rotating member, the shape of the mounting hole formed at the rotation center of the rotating member should be a polygon having the same shape as the cross section of the polygon shaft or a circular shape, and the polygon shaft can be inserted into the mounting hole. It is often performed to press fit.

JP-A-7-239596 JP 2005-69239 A

  However, when the rotating member is fixed to the round shaft, the non-circular portion of the round shaft and the non-circular hole of the rotating member have dimensional variations due to processing errors, so there is a backlash between the non-circular portion and the non-circular hole. Is likely to occur. Further, it is difficult to center the round shaft and the rotating member, and the rotating member may be assembled eccentrically with respect to the round shaft. When such a transmission device is used in an image forming apparatus, unevenness occurs in the rotation speed of the rotating member, causing various problems. For example, when the rotating member is mounted eccentrically on the rotating shaft of the photosensitive drum, unevenness in the density of the toner image on the surface of the photosensitive drum is caused by the rotational speed unevenness of the rotating member. It appears as a change in the image quality and deteriorates the image quality.

  In addition, if the mounting hole is circular when fixing the rotating member to the polygonal shaft, the function of retaining it will be satisfied by press-fitting the polygonal shaft, but from the viewpoint of variation in dimensions due to processing errors and press-fitting allowance. The function of detent is still not enough. If the mounting hole is a polygon, due to dimensional variations due to processing errors, backlash tends to occur between the polygon shaft and the mounting hole, and it is difficult to center the polygon shaft and the rotating member. That is, it has the same problem as when the rotating member is fixed to the round shaft.

  It is a technical object of the present invention to improve such a current situation and to accurately prevent rotation and prevention of loosening when fixing a polygonal shaft to a rotating member, and to eliminate rattling. Is.

  The invention of claim 1 is a transmission device comprising: a rotating member having a mounting hole in a rotation center portion; and a polygonal shaft that is press-fitted into the mounting hole of the rotating member. The inner peripheral surface of the mounting hole in the member has a plurality of inward projections arranged along the circumferential direction, and in the state where the polygon shaft is fitted in the mounting hole of the rotating member, Each inward projection is in contact with the outer peripheral flat surface of the polygon shaft.

  According to a second aspect of the present invention, in the transmission device according to the first aspect, a diameter of an inscribed circle inscribed at a tip of the inward projection portion group is smaller than a diameter of a circumscribed circle having a polygonal section in the polygon axis. And larger than the diameter of the inscribed circle of the cross-sectional polygon in the polygon axis.

  According to a third aspect of the present invention, in the transmission device according to the first or second aspect, the mounting hole of the rotating member has a tapered portion whose inner diameter decreases from the side where the polygon shaft is inserted toward the back. It is what you are doing.

  According to a fourth aspect of the present invention, in the transmission device according to any one of the first to third aspects, the rotating member is positioned on a concentric circle of the cylindrical hub body constituting the rotation center portion and the hub body. And a disc body connecting the rim body to the hub body, and no reinforcing rib is formed between the hub body and the rim body.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising the transmission device according to any one of the first to fourth aspects.

  According to the invention described in the claims of the present application, in a transmission device including a rotating member having a mounting hole in a rotation center portion, and a polygonal shaft fitted into the mounting hole of the rotating member by press-fitting. In addition, the inner peripheral surface of the mounting hole in the rotating member has a plurality of inward projections arranged along the circumferential direction, and the polygon shaft is fitted into the mounting hole of the rotating member. In this state, since each of the inward projections is in contact with the outer peripheral flat surface of the polygonal shaft, the polygonal shaft is rotated so that the top of the polygonal shaft does not contact the inward projections. It is press-fitted into the mounting hole of the member. By the press-fitting, the rotating member can be fixed to the polygonal shaft so that it cannot be removed without rattling. Further, the polygonal shaft does not rotate relative to the rotating member until each top of the polygonal shaft gets over the inwardly protruding portion, and the inwardly protruding portion is relative to the polygonal axis. Can function as a detent. In other words, the polygon shaft can be easily fixed to the rotating member without rattling without causing disconnection or idle rotation. In addition, since the conventional D-cut processing, E-ring and the like are not required, the processing effort and the number of parts can be reduced, and the manufacturing cost can be suppressed.

It is a schematic explanatory drawing of a printer. 2 is a schematic explanatory diagram of a toner supply structure. FIG. It is a schematic perspective view of a transmission. It is an expansion perspective view of a transmission gear. It is an enlarged front view of a hub body in the state where a polygonal shaft was fitted in an attachment hole. It is side surface sectional drawing of a transmission gear.

  Hereinafter, an embodiment in which a transmission device according to the present invention is applied to a tandem color digital printer (hereinafter referred to as a printer) which is an example of an image forming apparatus will be described with reference to the drawings. In addition, in the following description, when using a term indicating a specific direction or position (for example, “left / right”, “up / down”, etc.) as necessary, the direction orthogonal to the paper surface in FIG. ing. These terms are used for convenience of explanation, and do not limit the technical scope of the present invention.

(1). First, an outline of the printer 1 will be described with reference to FIG. As shown in FIG. 1, a printer 1 according to the embodiment includes an image processing device 3, a paper feeding device 4, a fixing device 5, and the like in a housing 2. Although not shown in detail, the printer 1 is connected to a network such as a LAN, and is configured to execute printing based on the command when receiving a print command from an external terminal (not shown). Yes.

  The image processing device 3 located at the center in the housing 2 plays a role of transferring a toner image formed on a photoconductor 13 as an example of an image carrier to a recording material P, and the intermediate transfer belt 6. , And yellow (Y), magenta (M), cyan (C), and black (K), a total of four image forming units 7 and the like are provided. In FIG. 1, for convenience of explanation, symbols Y, M, C, and K are attached to the image forming units 7 according to the reproduction colors.

  The intermediate transfer belt 6 is an endless belt made of a conductive material. The intermediate transfer belt 6 is wound around a driving roller 8 located on the right side of the central portion in the housing 2 and a driven roller 9 located on the left side of the central portion. ing. In this case, the intermediate transfer belt 6 circulates in the counterclockwise direction in FIG. 1 by rotating the drive roller 8 counterclockwise in FIG. 1 by transmitting power from a drive motor (not shown).

  A secondary transfer roller 10 is disposed on the outer peripheral side of the portion of the intermediate transfer belt 6 that is wound around the drive roller 8. The secondary transfer roller 10 is in contact with the intermediate transfer belt 6, and a portion between the intermediate transfer belt 6 and the secondary transfer roller 10 (contact portion) is a secondary transfer nip portion 11 that is a secondary transfer region. ing. The secondary transfer roller 10 rotates in the clockwise direction in FIG. 1 with the rotation of the intermediate transfer belt 6 or with the movement of the recording material P that is nipped and conveyed by the secondary transfer nip portion 11.

  A transfer belt cleaner 12 is disposed on the outer peripheral side of the portion of the intermediate transfer belt 6 wound around the driven roller 9. The transfer belt cleaner 12 is for removing untransferred toner remaining on the intermediate transfer belt 6, and is in contact with the intermediate transfer belt 6.

  The four image forming units 7 are arranged along the intermediate transfer belt 6 in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the left in FIG. They are arranged side by side. Each image forming unit 7 includes a photoreceptor 13 as an example of an image carrier that is driven to rotate clockwise in FIG. Around the photoconductor 13, a charger 14, a developing device 15, a primary transfer roller 16, and a photoconductor cleaner 17 are arranged in this order along the clockwise rotation direction in FIG. 1.

  The photosensitive member 13 is negatively charged and is configured to be driven to rotate clockwise in FIG. 1 by power transmission from a photosensitive motor (not shown). The charger 14 is of a roller charging type, and a voltage for charging the photosensitive member is applied to the charger 14 from a charging power source (not shown) at a predetermined timing. The developing unit 15 makes the electrostatic latent image formed on the photosensitive member 13 visible by reversal development using toner having a negative polarity.

  The primary transfer roller 16 is located on the inner peripheral side of the intermediate transfer belt 6 and faces the photoconductor 13 of the corresponding image forming unit 7 with the intermediate transfer belt 6 interposed therebetween. The primary transfer roller 16 rotates counterclockwise in FIG. 1 as the intermediate transfer belt 6 rotates. Between the intermediate transfer belt 6 and the primary transfer roller 16 (contact portion) is a primary transfer nip portion 18 which is a primary transfer region. The photoconductor cleaner 17 is for removing untransferred toner remaining on the photoconductor 13 and is in contact with the photoconductor 13.

  An exposure unit 19 is disposed below the four image forming units 7. The exposure unit 19 forms an electrostatic latent image on each photoconductor 13 with a laser beam based on image information from an external terminal or the like. A container mounting portion 40 is provided above the intermediate transfer belt 6. In the container mounting portion 40, a toner container 41 for storing toner supplied to each developing device 15 is detachably disposed. In FIG. 1, for convenience of explanation, the container mounting portion 40 and the toner container 41 are also denoted by symbols Y, M, C, and K according to the reproduction color.

  In each image forming unit 7, when a laser beam is projected from the exposure unit 19 onto the photosensitive member 13 charged by the charger 14, an electrostatic latent image is formed. The electrostatic latent image is reversely developed with the toner supplied from the developing device 15 to be a toner image of each color, and is transferred from the photoreceptor 13 in the order of yellow, magenta, cyan, and black in the primary transfer nip portion 18. Primary transfer is performed on the outer peripheral surface of the belt 6 and overlapped. Untransferred toner remaining on the photoreceptor 13 is scraped off by the photoreceptor cleaner 17 and removed from the photoreceptor 13. Then, when the recording material P passes through the secondary transfer nip portion 11, the superimposed four color toner images are collectively transferred onto the recording material P. Untransferred toner remaining on the intermediate transfer belt 6 is scraped off by the transfer belt cleaner 12 and removed from the intermediate transfer belt 6.

  The sheet feeding device 4 positioned below the image processing apparatus 3 is configured to feed the recording materials P in the plurality of stages (two stages in the embodiment) of the sheet feeding cassettes 21 and 22 that store the recording material P, and the sheet feeding cassettes 21 and 22. Feed rollers 23 and 24 that feed out one sheet at a time, a registration roller pair 25 that feeds the fed recording material P to the secondary transfer nip portion 11 at a predetermined timing, and the like. Each of the paper feed cassettes 21 and 22 is detachably disposed at the lower part of the housing 2. The recording material P in each of the paper feed cassettes 21 and 22 is sent out one by one from the uppermost one to the transport path 30 by the rotation of the corresponding feeding rollers 23 and 24.

  The conveyance path 30 passes from the paper feed cassettes 21 and 22 of the paper feed device 4 to the nip portion between the registration roller pair 25 and the secondary transfer nip portion 11 of the image processing device 3 to the fixing nip portion of the fixing device 5. 35. The conveyance path 30 extends from the fixing nip portion 35 to the discharge tray 27 on the upper surface of the housing 2 through the discharge roller pair 26.

  The fixing device 5 positioned above the secondary transfer roller 10 in the image processing apparatus 3 includes a heating roller 32 that is long in a direction orthogonal to the conveyance direction of the recording material P, and a pressure roller 34 that extends in parallel with the heating roller 32. It has. The pressure roller 34 is in contact with the heating roller 32, and a fixing nip portion 35, which is a fixing region, is between the heating roller 32 and the pressure roller 34 (contact portion). The recording material P on which the unfixed toner image has passed through the secondary transfer nip portion 11 is heated and pressurized when passing through the fixing nip portion 35, and the unfixed toner image is fixed on the recording material P. . Thereafter, the recording material P is discharged onto the paper discharge tray 27 by the rotation of the discharge roller pair 26.

(2). Developer and Toner Supply Structure Next, the developer 15 and the toner supply structure will be described with reference to FIGS. Here, the reason why the developing device 15 and the toner replenishment structure are described is that the case where the developing device 15 and the toner supply structure are applied to the power transmission structure of the conveying screw 48 in the toner hopper 47 is illustrated.

  As shown in FIGS. 1 and 2, each developing device 15 utilizes a known technique of electrophotography, and has a developing roller 42 having a plurality of permanent magnets in a cylindrical developing sleeve 43 and a screw blade. A plurality of stirring members 44 are provided. The developing device 15 contains a two-component developer D composed of toner and carrier.

  The toner in the developing device 15 is agitated and transferred by a plurality of agitating members 44, and is carried to the surface of the photoreceptor 13 by a carrier that stands up on the developing sleeve 43 by magnetic force. As a result, the electrostatic latent image on the photoreceptor 13 is visualized. Only the toner is consumed from the developer D by the development, and the carrier is not consumed. Therefore, the carrier is accommodated in the developing device 15 in advance. The consumed toner is replenished separately.

  The developing device 15 is provided with a toner concentration sensor 45 that detects an internal toner concentration (a ratio of toner in the developer D). The toner density sensor 45 of the embodiment is of a type that changes the oscillation frequency in accordance with, for example, a change in toner density. When the toner concentration in the developing device 15 detected by the toner concentration sensor 45 is equal to or lower than a predetermined concentration set in advance, toner is supplied from the toner hopper 47 between the container mounting portion 40 and the developing device 15 to the developing device 15. Is made.

  The container mounting portion 40 and the developing device 15 are connected in communication by a supply pipe 46. A toner hopper 47 that temporarily stores toner is provided in the middle of the supply pipe 46. A conveying screw 48 that supplies toner in the toner hopper 47 into the developing device 15 is disposed at the bottom of the toner hopper 47. The conveying screw 48 is connected to a screw drive motor 49 outside the toner hopper 47 so that power can be transmitted. The toner is replenished from the toner hopper 47 to the developing device 15 by rotating the conveying screw 48 by the screw drive motor 49.

  A toner amount sensor 50 that detects whether or not a predetermined amount of toner is stored is provided in the toner hopper 47. The toner amount sensor 50 of the embodiment uses a piezo element. When the toner amount in the toner hopper 47 detected by the toner amount sensor 50 becomes equal to or less than a predetermined amount set in advance, toner is supplied from the toner container 41 in the container mounting portion 40 to the toner hopper 47.

  The toner container 41 is connected to a container drive motor (not shown) in a state where it is disposed in the container mounting portion 40 so that power can be transmitted. By rotating and driving the toner container 41 by the container drive motor, toner is supplied to the toner hopper 47 from a toner discharge port (not shown) formed in the outer peripheral portion of the toner container 41.

(3). Detailed Structure of Transmission Device Next, a detailed structure of the transmission device 60 in the embodiment will be described with reference to FIGS. In the embodiment, the transmission device 60 is applied to the power transmission structure of the conveying screw 48. Therefore, the conveying screw 48 and its peripheral structure will be described in detail.

  As shown in FIG. 2, the tip end side of the screw shaft of the conveying screw 48 faces the inside of the developing device 15 through the supply pipe 46. The base end side of the screw shaft protrudes outward from the toner hopper 47. The protruding end portion on the screw shaft base end side is formed on a polygonal shaft 61 having a polygonal cross section. The polygon shaft 61 is a hexagonal shaft having a regular hexagonal cross section. The cross-sectional shape of the polygon shaft 61 is basically a regular polygon (in the embodiment, a regular hexagon) because it assumes the function of the rotation shaft.

  A transmission gear 62, which is an example of a rotating member, is fixed to the polygonal shaft 61 of the conveying screw 48. A combination of the polygon shaft 61 and the transmission gear 62 constitutes the transmission device 60. The transmission gear 62 meshes with a motor gear 63 fixed to a motor shaft of a screw drive motor 49 outside the toner hopper 47. The rotational power of the screw drive motor 49 is transmitted to the conveying screw 48 via the motor gear 63 and the transmission gear 62, and the conveying screw 48 is driven to rotate.

  As shown in FIG. 3 to FIG. 6, the transmission gear 62 includes a cylindrical hub body 64 that constitutes a rotation center portion thereof, a rim body 65 that is located on a concentric circle of the hub body 64, and a rim body on the hub body 64. And a disk body 66 for connecting 65. The transmission gear 62 of the embodiment is made of synthetic resin, and the hub body 64, the rim body 65, and the disk body 66 are integrally formed. External teeth that mesh with the motor gear 63 are formed on the outer peripheral side of the rim body 65. The disc body 66 has a thin annular shape in which one wide surface of the transmission gear 62 is stealed. In the embodiment, the hub body 64 and the rim body 65 are connected to each other by a thin annular disk body 66, and a reinforcing rib (eg, the hub body 64) commonly found between the hub body 64 and the rim body 65. The ribs extending radially from the like are not formed.

  The hub body 64 is formed in a bottomed cylindrical shape, and an inner peripheral side thereof is a mounting hole 67 for inserting the polygonal shaft 61 of the conveying screw 48. The mounting hole 67 is formed in a continuous form with a tapered portion 68 positioned on the side where the polygon shaft 61 is inserted (hereinafter referred to as the insertion side) and a straight portion 69 positioned on the back side. The tapered portion 68 has a shape in which the inner diameter is reduced from the insertion side toward the back side. A through hole 70 that penetrates into and out of the hub body 64 is formed in the bottom surface portion of the hub body 64.

  A plurality of inward projections 71 surrounding the polygon shaft 61 of the conveying screw 48 are formed on the inner peripheral surface of the mounting hole 67 so as to be arranged along the circumferential direction. The inward projections 71 of the embodiment are arranged at three locations at equal intervals along the circumferential direction so as to surround the polygonal shaft 61 from three directions. Further, each inward projection 71 extends long in the longitudinal direction of the mounting hole 67. In this case, each inward protruding portion 71 extends from the tapered portion 68 to the straight portion 69 in the mounting hole 67. It is sufficient that each inward projection 71 is formed on at least one of the tapered portion 68 and the straight portion 69.

  The polygonal shaft 61 of the conveying screw 48 is fitted into the mounting hole 67 of the hub body 64 in a state where it is difficult to be removed by being press-fitted from the tapered portion 68 side and is not relatively rotatable. When the polygon shaft 61 is press-fitted into the mounting hole 67 of the hub body 64, the hub body 64 is elastically deformed so as to expand in the radial direction, and the polygon shaft 61 is fixed to the mounting hole 67 of the hub body 64.

  When the transmission gear 62 is viewed from the insertion side, the diameter Da of the inscribed circle 72 inscribed in the tip of the inward projection 71 is greater than the diameter Db (diagonal distance) of the circumscribed circle 73 having a polygonal section in the polygon shaft 61. It is small and larger than the diameter Dc (opposite side distance) of the inscribed circle 74 having a polygonal section in the polygonal axis 61 (see FIG. 5). Therefore, in a state where the polygon shaft 61 is press-fitted into the mounting hole 67, each inward projection 71 contacts the outer peripheral flat surface 75 of the polygon shaft 61, and each apex 76 (adjacent outer flat surface) of the polygon shaft 61. The abutting portion of the surface 75) is located in a portion of the mounting hole 67 where the inward projection 71 is not present. Therefore, the polygonal shaft 61 is prevented from coming off by press-fitting into the hub body 64. Further, the polygon shaft 61 does not rotate relative to the transmission gear 62 (independent rotation) until each top portion 76 of the polygon shaft 61 gets over the inward projection 71. That is, the polygon shaft 61 is prevented from rotating by the presence of the inward projection 71.

  According to the above configuration, the inner peripheral surface of the mounting hole 67 in the transmission gear 62 has the plurality of inward projections 71 arranged in the circumferential direction, and the polygon shaft 61 is press-fitted into the mounting hole 67 of the transmission gear 62. Since each inward projection 71 contacts the outer peripheral flat surface 75 of the polygonal shaft 61 in the state where it is fitted in the polygonal shaft 61, the polygonal shaft 61 is set so that each top 76 does not hit the inward projection 71. It is press-fitted into the mounting hole 67 of the transmission gear 62. By the press-fitting, the transmission gear 62 can be fixed to the polygonal shaft 61 so that it cannot be removed without rattling. Further, the polygonal shaft 61 does not rotate relative to the transmission gear 62 until each top portion 76 of the polygonal shaft 61 gets over the inwardly protruding portion 71, and the inwardly protruding portion 71 is in relation to the polygonal shaft 61. Can function as a detent. That is, the polygonal shaft 61 can be easily fixed to the transmission gear 62 without rattling without causing disconnection or idle rotation.

  Furthermore, since the backlash between the polygon shaft 61 and the transmission gear 62 can be suppressed, the propagation of vibration due to backlash or the like to the image forming unit 7 such as the developing device 15 in the vicinity is reduced. For this reason, for example, image blurring (banding) or the like can be prevented, and image quality can be improved. In addition, since the conventional D-cut processing, E-ring and the like are not required, the processing effort and the number of parts can be reduced, and the manufacturing cost can be suppressed.

  In particular, in the embodiment, when the transmission gear 62 is viewed from the insertion side, the diameter Da of the inscribed circle 72 inscribed in the tip of the inward projection 71 is larger than the diameter Dc of the inscribed circle 74 having a polygonal section in the polygon shaft 61. Since it is large, the polygonal shaft 61 can be reliably press-fitted into the mounting hole 67 of the transmission gear 62 while avoiding the inward projections 71. Since the diameter Da of the inscribed circle 72 inscribed at the tip of the inward projection 71 is smaller than the diameter Db of the circumscribed circle 73 having a polygonal section in the polygonal axis 61, each apex 76 of the polygonal axis 61 is inward. Thus, the polygonal shaft 61 can be reliably prevented from rotating relative to the transmission gear 62.

  Furthermore, since the mounting hole 67 of the transmission gear 62 has a tapered portion 68 whose inner diameter decreases from the insertion side toward the back, when the polygon shaft 61 is press-fitted into the mounting hole 67 of the transmission gear 62. The polygon shaft 61 can be smoothly guided to the mounting hole 67. In addition, the transmission gear 62 includes a cylindrical hub body 64 constituting a rotation center portion, a rim body 65 located on a concentric circle of the hub body 64, and a disk body 66 connecting the rim body 65 to the hub body 64. Since the reinforcing rib is not formed between the hub body 64 and the rim body 65, when the polygon shaft 61 is press-fitted into the mounting hole 67 of the transmission gear 62, it is expanded in the radial direction. The elastic deformation of the hub body 64 can be allowed, and an appropriate fitting state between the mounting hole 67 of the transmission gear 62 and the polygon shaft 61 can be easily secured.

(4). Others The present invention is not limited to the above-described embodiment, and can be embodied in various forms. For example, a printer has been described as an example of the image forming apparatus. However, the present invention is not limited to this, and a copier, a facsimile, or a multifunction machine having these functions combined may be used. Further, the transmission device 60 is not limited to being applied to the power transmission structure of the conveying screw 48. In the image forming apparatus, for example, the transmission device 60 may be a combination of a rotating member such as a gear or a roller and a polygon shaft that is pivotally supported by the rotating member. If applicable. In addition, the structure of each part is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

1 Printer (image forming device)
47 Toner hopper 48 Conveying screw 49 Screw drive motor 60 Transmission device 61 Polygon shaft 62 Transmission gear 64 Hub body 65 Rim body 66 Disk body 67 Mounting hole 68 Tapered portion 71 Inward projection 72 Inwardly contact the tip of the inward projection Inscribed circle 73 circumscribed circle 74 of polygon in section on polygonal axis Inscribed circle 75 of polygon in section on polygon axis Peripheral flat surface 76

Claims (5)

A transmission device comprising: a rotating member having a mounting hole in a rotation center portion; and a polygonal shaft fitted by press-fitting into the mounting hole of the rotating member,
The inner peripheral surface of the mounting hole in the rotating member has a plurality of inward projections arranged along the circumferential direction,
In a state where the polygon shaft is fitted into the mounting hole of the rotating member, the inwardly protruding portions are brought into contact with the outer peripheral flat surface of the polygon shaft.
Transmission device. The diameter of the inscribed circle inscribed in the tip of the inward projection portion group is smaller than the diameter of the circumscribed circle of the polygonal section in the polygon axis, and the diameter of the inscribed circle of the section polygon in the polygon axis Greater than,
The transmission according to claim 1. The mounting hole of the rotating member has a tapered portion whose inner diameter decreases from the side where the polygon shaft is inserted toward the back.
The transmission device according to claim 1 or 2. The rotating member includes a cylindrical hub body that forms the rotation center portion, a rim body that is located on a concentric circle of the hub body, and a disk body that connects the rim body to the hub body. ,
No reinforcing rib is formed between the hub body and the rim body.
The transmission device according to any one of claims 1 to 3. The transmission device according to claim 1 is provided.
Image forming apparatus.

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