JP2007024085A - Driving force transmission device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force transmission device having a high degree of freedom in designing the shape of a gear for suppressing the breakage of the gear in simple construction, and to provide an image forming device. <P>SOLUTION: The driving force transmission device comprises a driving shaft into which a parallel pin 21 is inserted, and the gear 10 having a pair of grooves 11 in the radial direction. The parallel pin 21 is inserted into the grooves 11 of the gear 10. Besides, on the wall faces at the ends of the grooves 11, protruded portions 12 are provided, respectively, which are protruded in the radial direction. The protruded portions 12 restrict the movement of the parallel pin 21 in the radial direction. The protruded portions 12 at the ends of the grooves 11 form tapered surfaces. The parallel pin 21 inserted into the grooves 11 is therefore held between the protruded portions 12 at both ends. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a driving force transmission device that transmits rotational driving force and an image forming apparatus including the driving force transmission device. More specifically, the present invention relates to a driving force transmission device that transmits rotational driving force using parallel pins, and an image forming apparatus including the driving force transmission device.

Conventionally, in a driving force transmission device used in an electrophotographic image forming apparatus, a driving shaft having a parallel pin inserted in a through hole penetrating in a radial direction (radial direction) and the parallel pin are arranged. Some have a gear having a pair of grooves. In such a driving force transmission device, the gear and the driving shaft are connected by fitting the parallel pin of the driving shaft and the groove of the gear to transmit the rotational driving force (for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-94029

  However, the conventional driving force transmission device described above has the following problems. In other words, the gear shape is designed to match the length of the parallel pins to prevent radial play between the parallel pins and the grooves. For this reason, the number of gear teeth is determined by the length of the parallel pins, and the degree of freedom in gear design is lost.

  Further, the parallel pin moves in the radial direction, the gear stress value increases, and the gear is easily damaged. Specifically, in such a driving force transmission mechanism, as shown in FIG. 9, the load point between the parallel pin 21 and the gear 10 (enclosure A in FIG. 9, “stress concentration location A”), groove, Stress concentration is likely to occur in the vicinity of the corner portion of the end portion 11 in the radial direction (box B in FIG. 9, referred to as “stress concentration portion B”). Therefore, it is not preferable that the stress concentration point A and the stress concentration point B overlap from the viewpoint of generating an excessive stress value. However, the parallel pin 21 is not fixed to the drive shaft. Therefore, the parallel pin 21 moves to one side in the radial direction during operation. Then, the parallel pin 21 moves and abuts against the end portion in one of the grooves 11 so that the stress concentration portion A and the stress concentration portion B overlap. As a result, an excessive stress value is generated.

  Further, in the conventional driving force transmission device, in order to prevent the gear from being damaged due to the above-described problem, the wall surface portion of the groove 11 (X in FIG. 9) is made thick. However, if the wall thickness of the groove 11 is increased, sink marks are likely to occur during molding. As a result, the gear shape varies. In addition, the cost increases and the space increases as the material increases.

  In order to suppress the movement of the parallel pin, it is conceivable that the parallel pin is fixed to the gear by a pressing part such as a screw (for example, Patent Document 1). However, an increase in the number of parts and the number of processes are inevitable.

  The present invention has been made to solve the problems of the conventional driving force transmission device described above. That is, an object of the present invention is to provide a driving force transmission device and an image forming apparatus that have a high degree of freedom in designing the gear shape and that suppress damage to the gear with a simple configuration.

  A driving force transmission device designed to solve this problem is provided with a driving shaft member into which a parallel pin is inserted and a pair of grooves facing each other in the radial direction across a through hole into which the driving shaft member is inserted. A drive force transmission device having a gear member and having a parallel pin of a drive shaft member inserted into a groove portion of the gear member, and a protrusion projecting toward a radial center portion side of the groove portion in a radial direction It has the part.

  The driving force transmission device of the present invention transmits a rotational driving force by combining a parallel pin and a gear member. And in order to insert a parallel pin in a gear member, a pair of groove part is provided in the gear member. In addition, a protrusion that protrudes toward the center in the radial direction is provided at the end of the groove. By this protrusion, movement of the parallel pin in the groove in the radial direction can be restricted, and the parallel pin can be continuously held at the center in the radial direction. That is, the deviation of the position of the parallel pin is suppressed, and the overlap between the end of the parallel pin (the load point of the parallel pin) and the end of the groove can be avoided. Further, at the load point of the parallel pin, the pressure from the parallel pin can be received by the surface as the distance from the end of the groove portion increases. Therefore, the stress value at the load point of the parallel pin is small. Therefore, generation of an excessive stress value can be avoided.

  Furthermore, in the driving force transmission device of the present invention, the movement of the parallel pins in the radial direction can be restricted by adjusting the protrusion length of the protrusion. Therefore, the gear shape can be designed without being restricted by the length of the parallel pin. Therefore, the degree of freedom in designing the gear shape is high.

  Further, it is better that the protrusion length of the protrusion portion of the driving force transmission device is longer as it approaches the groove bottom surface of the groove portion. In other words, the parallel pin can be guided to the central portion of the gear member by forming the protruding portion in a tapered shape. Further, the parallel pins can be sandwiched by the protrusions at both ends, and radial play between the parallel pins and the grooves can be eliminated.

  Another driving force transmission device according to the present invention includes a driving shaft member into which a parallel pin is inserted, and a gear member provided with a pair of grooves facing each other in the radial direction across a through hole into which the driving shaft member is inserted. And a drive force transmission device in which parallel pins of the drive shaft member are inserted into the groove portion of the gear member, wherein the depth of the groove portion of the gear member becomes deeper as it approaches the central portion in the radial direction. It is said.

  That is, in another driving force transmission device of the present invention, the groove bottom surface (web surface) of the groove portion is tapered. Therefore, the web surface can guide the parallel pin to the central portion and bring the parallel pin to the central portion of the gear member. As a result, the stress concentration points are separated and the generation of excessive stress values can be avoided. Further, the parallel pins can be sandwiched between the web surfaces at both ends, and radial play between the parallel pins and the grooves can be eliminated. Therefore, the gear shape can be designed without being restricted by the length of the parallel pin. Therefore, the degree of freedom in designing the gear shape is high.

  According to the present invention, the movement in the radial direction between the parallel pin and the groove is restricted by providing a protrusion at the end of the groove of the gear member or by forming the web surface of the groove into a tapered shape. Therefore, the design of the gear shape is not limited by the length of the parallel pin. In addition, by maintaining the parallel pin at the center of the gear member, it is possible to avoid the generation of an excessive stress value. Therefore, the driving force transmission device of the present invention and the image forming apparatus equipped with the driving force transmission device have a high degree of freedom in designing the gear shape, and can prevent damage to the gear member with a simple configuration.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a driving force transmission device provided in an electrophotographic laser printer.

[First embodiment]
The image forming apparatus according to the first embodiment is an electrophotographic laser printer. As shown in FIG. 1, the image processing unit includes a photosensitive drum 1, a charging device 2, a developing device 4, a transfer device 5, A cleaning device 6 is arranged, and a laser oscillator 3, a polygon mirror 31, and a reflection mirror 32 are arranged in the optical system. In addition, a paper feed roller 7, a paper discharge roller 8, a paper feed sensor 71, a paper discharge sensor 81, a fixing device 9 and the like are arranged in the transport unit. In this embodiment, the charging device 2, the transfer device 5, and the fixing device 9 are all roller-shaped. The cleaning device 6 uses a cleaning blade.

  Next, the operation of the laser printer configured as described above will be briefly described. The photosensitive drum 1 rotates in the direction of the arrow in FIG. 1 and the surface is uniformly charged by the charging device 2. Further, the laser light is modulated and emitted from the laser oscillator 3 based on the image signal. This laser beam is scanned in the main scanning direction by the polygon mirror 31, reflected by the reflection mirror 32, and incident on the photosensitive drum 1. Thereby, an electrostatic latent image is formed on the photosensitive drum 1.

  This electrostatic latent image is developed by the developing device 4 to become a toner image. The toner image is transferred onto the recording paper S fed by the paper feed roller 7 by the transfer device 5 disposed facing the photosensitive drum 1. Thereafter, the recording paper S to which the toner image has been transferred is heated while being pressed by the fixing device 9, and the toner image is melted and fixed on the recording paper S by the heat. After the image is fixed, the recording paper S is discharged out of the apparatus by a paper discharge roller 8. With the above operation, printing for one sheet is performed.

  Next, the driving force transmission device will be described. The driving force transmission device of this embodiment is installed in the image forming apparatus, and includes a photosensitive drum 1, a charging device 2, a developing device 4, a transfer device 5, a paper feeding roller 7, a paper discharging roller 8, a fixing device. The rotational driving force from the driving source is transmitted to various rotating members included in the device 9 and the like.

  As shown in FIGS. 2 to 3, the driving force transmission device 100 includes a driving motor M, a motor gear 10M fixed to the output shaft of the driving motor M, and a plurality of gears 10D that transmit the rotational driving force from the motor gear 10M. And a drive shaft 20D. In the configuration shown in FIG. 2, the rotational driving force from the motor gear 10M is transmitted in the order of the gear 10D (1), the gear 10D (2), the gear 10D (3), the (drive shaft 20D), and the gear 10D (4). . The configurations of the gear 10D and the drive shaft 20D are not limited to those shown in FIGS. 2 to 3, and various combinations can be realized.

  Then, for example, by engaging the charging gear 10R fixed to the rotating shaft 20R of the charging roller 2R and the gear 10D (4), the rotational driving force from the driving motor M is transmitted to the charging roller 2R. Thereby, the charging roller 2R is rotationally driven at a predetermined speed. In addition, the rotational driving force of the driving motor M is transmitted to various rotating members included in the photosensitive drum 1, the developing device 4, the transfer device 5, the paper feeding roller 7, the paper discharging roller 8, the fixing device 9, and the like. .

  Next, a connection mechanism between the gear 10D (4) of the driving force transmission device 100 and the driving shaft 20D will be described. In the following description, the gear 10D (4) is referred to as the gear 10, and the drive shaft 20D is referred to as the drive shaft 20.

  First, FIG. 4 shows the structure of the drive shaft 20. The drive shaft 20 is formed with a through hole 22 penetrating in the radial direction. The parallel pin 21 is inserted into the through hole 22, and both end portions of the parallel pin 21 are in a state of protruding from the drive shaft 20.

  Next, the structure of the gear 10 is shown in FIG. The gear 10 is provided with a through hole 15 into which the drive shaft 20 is inserted at the center thereof. A pair of grooves 11 facing in the radial direction across the through hole 15 are formed. The groove 11 can accommodate the parallel pin 21, and the distance from the end of one groove 11 to the end of the other groove 11 is longer than the length of the parallel pin 21 that accommodates. And the gear 10 and the drive shaft 20 are connected by accommodating the parallel pin 21 inserted in the drive shaft 20 in the groove | channel 11 provided in the gear 10. FIG. When the parallel pin 21 pushes the gear 10, the rotational driving force is transmitted from the drive shaft 20 to the gear 10.

  Further, as shown in FIG. 5, the gear 10 of the present embodiment is provided with a protrusion 12 that protrudes toward the center in the radial direction on the wall surface of the end of the groove 11. When the parallel pin 21 is inserted into the groove 11 by the projection 12, the movement of the parallel pin 21 in the radial direction is restricted as shown in FIG. That is, the end of the parallel pin 21 is suppressed from approaching one end of the groove 11, and the position of the parallel pin 21 can be maintained at the center in the radial direction.

  Further, the protrusion 12 in the groove 11 has a tapered shape as shown in FIG. That is, the protrusion length of the protrusion 12 becomes longer as it approaches the groove bottom surface of the groove 11. Therefore, the parallel pin 21 inserted into the groove 11 is guided by the taper surface of the projection 12 and is brought close to the center of the gear 10. And it hold | maintains in the state pinched | interposed into the projection part 12 of both ends. Therefore, the parallel pin 21 can be easily installed at the center of the gear 10 and radial play between the parallel pin 21 and the groove 11 can be eliminated.

[Second form]
In the driving force transmission device 200 according to the second embodiment, as shown in FIG. 8, the groove bottom surface 13 (web surface) of the groove 11 of the gear 10 is tapered. That is, the depth of the groove portion 11 increases as the distance from the end portion of the groove portion 11 increases. The configuration of the image forming apparatus provided with the driving force transmission device 200 is the same as that of the first embodiment (see FIG. 1), and the description thereof is omitted.

  In the driving force transmission device 200, the web surface 13 has a tapered shape, so that the same effect as that of the protrusion 12 of the first embodiment can be obtained. That is, the parallel pin 21 inserted into the groove 11 is brought close to the central portion of the gear 10 along the tapered web surface 13 and held in a state of being sandwiched by the web surface 13. Therefore, the end of the parallel pin 21 is suppressed from approaching one end of the groove 11, and the position of the parallel pin 21 can be maintained at the center in the radial direction.

  Further, since the web surface 13 which is a tapered surface guides the parallel pin 21, the position of the parallel pin 21 can be easily installed in the center portion of the gear 10 and is generated between the parallel pin 21 and the groove 11. The play in the radial direction can be eliminated.

  As described above in detail, the image forming apparatus according to the present embodiment includes the drive shaft 20 in which the parallel pins 21 are inserted and the gear 10 in which the pair of grooves 11 are provided in the radial direction. The driving force transmission device is provided with the parallel pin 21 inserted into the groove 11 of the gear 10. The driving force transmission device has means for arranging the parallel pin 21 at the center of the gear 10. Specifically, as means for disposing the parallel pin 21 at the center of the gear 10, for example, the protrusion 12 is disposed at the end of the groove 11 as in the first embodiment, or as in the second embodiment. It corresponds to making the web surface 13 of the groove | channel 11 into a taper shape. By these means, movement of the parallel pin 21 to one end of the groove 11 is restricted. That is, the movement of the parallel pin 21 can be restricted by adjusting the protrusion length of the protrusion 12 and the angle of the tapered surface. Therefore, the design of the shape of the gear 10 is not limited by the length of the parallel pin 21.

  Further, by arranging the parallel pin 21 at the center of the gear 10, it is possible to avoid the generation of an excessive stress value (that is, the overlap between the stress concentration location A and the stress concentration location B in FIG. 9). For this reason, it is not necessary to increase the wall thickness of the groove 11 or to fix the parallel pin 21 with a screw or the like. Therefore, it is possible to prevent the gear 10 from being damaged without causing a variation in gear shape and an increase in cost. Therefore, a driving force transmission device and an image forming apparatus that have a high degree of freedom in design of the gear shape and suppress gear breakage with a simple configuration are realized.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, a copy machine, a scanner, a FAX, or the like can be applied as long as it has a driving force transmission device. Further, not limited to the electrophotographic method, for example, an ink jet method may be used.

  Further, although a roller-shaped photosensitive drum is used as the image carrier, a belt-shaped photosensitive belt may be used. In addition to the roller charging method, the charging device may use a corona discharge charging charger, blade, brush, or the like. The exposure apparatus may be a laser or LED. The transfer device may use a transfer charger in addition to the transfer roller. Alternatively, in addition to a method of directly transferring a toner image from a photosensitive member to a sheet, a method of providing an intermediate transfer member and performing transfer in two or more stages may be used. In addition to the cleaning blade, the cleaning device may be a cleaning brush, a cleaning roller, or a combination thereof. Alternatively, the transfer residual toner may be collected by a developing device. In addition to the fixing roller, the fixing device may use a fixing belt or a non-contact type.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. It is FIG. (1) which shows schematic structure of the driving force transmission apparatus concerning embodiment. It is FIG. (2) which shows schematic structure of the driving force transmission apparatus concerning embodiment. It is a figure which shows schematic structure of a drive shaft. It is a figure which shows schematic structure of a gear. It is a front view (1st form) which shows the state in which the parallel pin was inserted in the groove | channel of a gear. It is sectional drawing (1st form) which shows the state in which the parallel pin was inserted in the groove | channel of a gear. It is sectional drawing (2nd form) which shows the state in which the parallel pin was inserted in the groove | channel of a gear. It is a front view (conventional form) which shows the state in which the parallel pin was inserted in the groove | channel of a gear.

Explanation of symbols

10 Gear (Gear member)
11 Groove (groove)
12 Protrusion (protrusion)
13 Web surface (groove bottom)
15 Through hole (through hole)
20 Drive shaft (drive shaft member)
21 Parallel pin (parallel pin)
22 Through-hole 100 Driving force transmission device (driving force transmission device)

Claims (6)

A drive shaft member into which a parallel pin is inserted; and a gear member provided with a pair of grooves facing each other in the radial direction across a through hole into which the drive shaft member is inserted. In a driving force transmission device in which is inserted into the groove of the gear member,
A driving force transmission device having a projecting portion projecting toward a central portion in the radial direction at an end portion in the radial direction of the groove portion. In the driving force transmission device according to claim 1,
The driving force transmission device according to claim 1, wherein a protrusion length of the protrusion is longer as approaching a groove bottom surface of the groove. A drive shaft member into which a parallel pin is inserted; and a gear member provided with a pair of grooves facing each other in the radial direction across a through hole into which the drive shaft member is inserted. In a driving force transmission device in which is inserted into the groove of the gear member,
The depth of the groove part of the said gear member is so deep that it approaches the center part of a radial direction, The driving force transmission apparatus characterized by the above-mentioned. A pair of image forming means that includes a rotation unit and forms an image using the rotation unit, a drive shaft member into which a parallel pin is inserted, and a pair opposed in the radial direction across a through hole into which the drive shaft member is inserted An image forming apparatus comprising: a gear member provided with a groove portion; and a driving force transmission device formed by inserting parallel pins of the drive shaft member into the groove portion of the gear member.
The gear member of the driving force transmission device has a protruding portion protruding toward a central portion in the radial direction at an end portion in the radial direction of the groove portion. The image forming apparatus according to claim 4,
The image forming apparatus according to claim 1, wherein a protrusion length of the protrusion portion is longer as approaching a groove bottom surface of the groove portion. A pair of image forming means that includes a rotation unit and forms an image using the rotation unit, a drive shaft member into which a parallel pin is inserted, and a pair opposed in the radial direction across a through hole into which the drive shaft member is inserted An image forming apparatus comprising: a gear member provided with a groove portion; and a driving force transmission device formed by inserting parallel pins of the drive shaft member into the groove portion of the gear member.
2. An image forming apparatus according to claim 1, wherein the depth of the groove portion of the gear member of the driving force transmission device becomes deeper as it approaches the central portion in the radial direction.

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