JP2012230418A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus able to improve a weight reduction, cost reduction, and an assembly improvement, and also able to prevent damage to components.SOLUTION: The image forming apparatus has a drive unit which is attached detachably to an image forming apparatus main body and is constituted by supporting a gear train transmitting rotational power to a plurality of rollers for conveying paper sheets, rotatably on a housing 2 via a pin 4. In the image forming apparatus, the housing 2 is composed of a resin housing. Also, a groove 8 is formed around a boss 5 formed on the resin housing 2, thereby forming a thin-wall cylindrical part 5a in part of the boss 5. A separation preventing rib 7 is projected all around the inner periphery of the thin-wall cylindrical part 5a. The pin 4 is inserted into a pin insertion hole 6 in the boss 5, and the separation prevention rib 7 projecting from the thin-wall cylindrical part 5a of the boss 5 is engaged with an engagement groove 4b formed in the outer periphery of the pin 4, thereby fixing the pin 4 to the resin housing 2.

Description

  The present invention relates to an image forming apparatus including a drive unit configured to rotatably support a gear train that transmits rotational power to a plurality of rollers that convey a recording material such as paper, and the like on a resin housing.

  In an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, a recording material such as paper is transported along a transport path in the main body by a plurality of transport rollers, and an image is formed in the process. The plurality of transport rollers are rotationally driven by the rotational power transmitted through the gear train from the electric motor as a drive source.

  By the way, an electric motor as a drive source, a gear train that transmits the rotational power of the electric motor to the transport roller, an electromagnetic clutch that connects and disconnects the power transmission by the gear train, etc. are collectively housed in a housing and unitized as a drive unit. There has been proposed an image forming apparatus that employs a configuration in which a drive unit is detachably attached to a side portion of a main body.

  Each gear constituting the gear train provided in such a drive unit is supported by a pin separate from the housing, but the pin is attached to the sheet metal housing by caulking. Alternatively, as shown in FIG. 11, a boss 105 is formed in the housing, and a plurality of (three in the illustrated example) retaining projections are provided on the inner periphery of the pin insertion hole 106 penetrating through the center of the boss 105. 107 is protruded, a pin (not shown) is inserted into the pin insertion hole 106 of the boss 105, and the protrusion 107 protruded from the inner periphery of the pin insertion hole 106 of the boss 105 into an engagement groove formed on the outer periphery of the pin. A configuration has been employed in which the pins are prevented from coming off from the housing by engaging them.

JP 2004-205964 A JP-A-7-160172

  However, if the housing of the drive unit is made of sheet metal and the pins supporting the gears are made of metal as in the conventional case, the drive unit becomes heavier and requires a caulking process of the metal pins to the housing, resulting in an increase in cost. There was a problem.

  Further, as shown in FIG. 11, a plurality of protrusions 107 are formed on the inner periphery of a pin insertion hole 106 provided through the boss 105 of the housing, and these protrusions 107 are formed on the outer periphery of a pin (not shown). In the configuration in which the pin is prevented from coming off from the housing by being engaged with the engaging groove, when the pin is inserted into the pin insertion hole 106 of the boss 105, the protrusion 107 may break and enter the housing. .

  The present invention has been made in view of the above-described problems, and an object of the processing is to form an image that can reduce the weight of the drive unit, reduce the cost and improve the assemblability, and prevent damage to the components. To provide an apparatus.

  In order to achieve the above object, the invention according to claim 1 is detachably attached to the main body of the image forming apparatus, and a gear train for transmitting rotational power to a plurality of rollers for conveying paper can be rotated to the housing via pins. In the image forming apparatus having the drive unit configured to be supported on the housing, the housing is formed of a resin housing, and a groove is formed around the boss formed on the resin housing to form a thin cylinder at a part of the boss. A retaining rib is provided on the inner periphery of the thin cylindrical portion, and the pin is inserted into the pin insertion hole of the boss, and the engagement groove formed on the outer periphery of the pin A drive unit for fixing the pin to the resin housing by engaging a retaining rib protruding from the thin cylindrical portion of the boss is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the pin of the drive unit is a resin pin.

  According to a third aspect of the present invention, in the first aspect of the present invention, the pin of the drive unit is a resin pin or a metal pin depending on the magnitude of a load applied thereto.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the semi-fixed side end of the pin of the drive unit is supported on the image forming apparatus main body side.

  According to the first aspect of the present invention, since the housing of the drive unit is a lightweight resin housing, the drive unit and the image forming apparatus including the drive unit can be reduced in weight and cost. In addition, the drive unit pins are fixed to the resin housing by the insertion method instead of the conventional caulking method, so that the conventional caulking process is not required, the drive unit is easy to assemble, and the drive unit is reduced by reducing the number of assembly steps. In addition, the cost of the image forming apparatus including the same can be reduced. In the drive unit, a groove is formed around the boss formed in the resin housing to form a thin cylindrical portion that is easily elastically deformed in a part of the boss, and a retaining rib is provided on the inner periphery of the thin cylindrical portion. Since the protrusion is provided over the entire circumference, the thin cylindrical portion of the boss is easily deformed when the pin is inserted and fixed into the pin insertion hole of the boss. For this reason, the pin can easily get over the retaining rib formed on the inner periphery of the thin cylindrical portion, and the retaining rib is engaged with the engaging groove formed on the outer periphery of the pin so that the pin is It can be securely fixed to the resin housing. In this case, since the retaining rib is protruded over the entire circumference of the thin cylindrical portion of the boss, when the pin gets over the retaining rib, the stress is uniformly applied to the entire rib. Excessive stress does not act locally. Therefore, damage to the ribs is prevented, and the occurrence of a problem that the fragments enter the resin housing is prevented.

  According to the second aspect of the present invention, since the pins of the drive unit are also light resin pins, the drive unit and the image forming apparatus including the drive unit can be further reduced in weight.

  According to invention of Claim 3, a resin pin or a metal pin can be selected according to the load which acts on the pin of a drive unit, a high-strength metal pin is used for the pin which a big load acts, Durability can be improved and weight can be reduced by using a lightweight resin pin for the pin on which no load acts.

  According to the fourth aspect of the invention, since the side opposite to the fixed side of the pin is supported on the image forming apparatus main body side in the drive unit, the pin is securely supported by both ends, and the gear supported by the pin is supported. Falling is reliably prevented.

1 is a perspective view of a drive unit and an image forming apparatus main body of an image forming apparatus according to the present invention. 1 is a perspective view of a drive unit of an image forming apparatus according to the present invention. 1 is a perspective view of a drive unit of an image forming apparatus according to the present invention. It is a fragmentary perspective view of the resin housing before attaching a pin in a drive unit. It is a fragmentary perspective view of the resin housing after attaching a pin in a drive unit. It is a surface side perspective view of the boss formed in the resin housing of the drive unit with which the image forming apparatus concerning the present invention was equipped. It is a back surface side perspective view of the boss | hub formed in the resin housing of the drive unit with which the image forming apparatus which concerns on this invention was equipped. It is a perspective view of the pin of a drive unit. It is a boss section sectional view of a resin housing before attaching a pin in a drive unit. It is a boss section sectional view of a resin housing after attaching a pin in a drive unit. It is a perspective view which shows the boss | hub shape of the conventional drive unit.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a drive unit and an image forming apparatus main body of an image forming apparatus according to the present invention, and FIGS. 2 and 3 are perspective views of the drive unit.

  As shown in FIG. 1, the image forming apparatus according to the present invention includes a drive unit 1 that is detachably assembled to the main body frame 100, and is not disposed in the image forming apparatus main body by the drive unit 1. Various rollers such as a pick-up roller, a feed roller, a retard roller, a conveyance roller, a registration roller pair, a conveyance roller pair, and a paper discharge roller pair are driven to rotate.

  2 and 3, the drive unit 1 is divided into a main body side unit 1A and an anti-main body side unit 1B. As shown in FIG. 2, the main body frame 100 of the main body side unit 1A is divided. A plurality of gears G are rotatably supported on the surface (the surface on the near side in FIG. 2) opposite to each other, and these constitute a gear train for transmitting power to various rollers. Although not shown, a plurality of gears are also rotatably supported on the surface of the opposite main body side unit 1B facing the main body side unit 1A, and these constitute a gear train for transmitting power to various rollers. .

  Thus, a positioning boss (not shown) projecting from the non-main body unit 1B is fitted into a positioning hole (not shown) formed in the main unit 1A, and both units 1A and 1B are positioned and joined. The drive unit 1 shown in the figure is assembled, and the drive unit 1 is detachably assembled to the main body frame 100 of the image forming apparatus as described above.

  Here, the main unit 1A and the non-main unit 1B of the drive unit 1 include resin housings 2 and 3, respectively. These resin housings 2 and 3 are made of thermoplastic resin such as ABS resin or POM (polyacetal). Manufactured by injection molding. In this injection molding, a thermoplastic resin is melted in a heating cylinder, and the molten resin is injected from a plurality of gates into a cavity in a mold at a predetermined pressure.

  As shown in FIG. 2, for example, a plurality of gears G provided in the main unit 1A are rotatably supported by pins 4 attached to the resin housing 2, but each pin 4 is a conventional one. Instead of the caulking method, it is attached to the resin housing 2 by an insertion method. Hereinafter, a structure for fixing the pin 4 to the resin housing 2 will be described with reference to FIGS.

  4 is a partial perspective view of the resin housing before the pin is attached, FIG. 5 is a partial perspective view of the resin housing after the pin is attached, FIG. 6 is a front side perspective view of a boss formed on the resin housing, and FIG. FIG. 8 is a perspective view of the pin, FIG. 9 is a sectional view of the boss portion of the resin housing before the pin is attached, and FIG. 10 is a sectional view of the boss portion of the resin housing after the pin is attached. .

  As shown in FIG. 4, bosses 5 for inserting and fixing the pins 4 shown in FIG. 8 are formed at a plurality of locations where the gear G of the resin housing 2 of the main unit 1A is disposed. Here, as shown in FIG. 6, the surface side of each boss 5 (the main body frame 100 side) protrudes from the surface of the resin housing 2 in a ring shape, and a notch for inserting the pin 4 at the center thereof. A circular pin insertion hole 6 is formed. That is, a flat surface 6 a is formed on a part of the inner periphery of the pin insertion hole 6, and the pin insertion hole 6 has a notch circle shape. The pin insertion hole 6 has a retaining rib 7 projecting integrally on the inner peripheral surface excluding the flat surface 6a over the entire circumference.

  Further, as shown in FIGS. 7 and 9, a groove 8 is formed around the boss 5 on the back side (on the main body frame 100 side) of the resin housing 2, and the portion facing the back side of the boss 5 is A thin cylindrical portion 5a which is thin with respect to the surface side is formed, and a pin insertion hole 6 is provided through the inside. For this reason, the thin cylindrical portion 5a of the boss 5 is easily elastically deformed, and the retaining rib 7 is formed in this portion.

  On the other hand, as shown in FIG. 8, an engagement groove 4 a for preventing a gear from being removed is formed at both ends in the axial direction of the pin 4, that is, at a distal end side, and an engagement for preventing a pin from being removed at the opposite base end side. A groove 4b and a D-cut 4c are formed.

  Thus, the pin 4 is inserted and fixed to the boss 5 of the resin housing 2 in the following manner. That is, the pin 4 is inserted from the surface side into the pin insertion hole 6 formed in the boss 5 of the resin housing 2 with the base end side first. At this time, the D-cut 4c formed on the base end side of the pin 4 and the flat surface 6a formed in the pin insertion hole 6 of the boss 5 are made to coincide with each other, so that the pin 4 is prevented from rotating. The

  When the pin 4 is inserted into the pin insertion hole 6 of the boss 5 as described above, the pin 4 gets over the retaining rib 7 projecting from the inner periphery of the pin insertion hole 6 of the boss 5. A groove 8 is formed around the boss 5 on the back surface side (on the main body frame 100 side) of the housing 2 (see FIG. 7), and the portion facing the back surface side of the boss 5 is thinner than the front surface side. Since the cylindrical portion 5a is formed, the thin cylindrical portion 5a of the boss 5 is more easily elastically deformed than other portions. Further, since the retaining rib 7 protrudes from the thin cylindrical portion 5a that is easily elastically deformed, the pin 4 easily gets over the retaining rib 7, and the engaging groove 4b formed on the outer periphery of the base end portion. The retaining rib 7 is easily engaged with the pin 4 so that the pin 4 is fixed to the boss 5 (resin housing 2), and the boss 5 is reliably prevented from coming off (see FIGS. 5 and 10).

  Thus, when the pin 4 is inserted and fixed to the boss 5 of the resin housing 2 by the above procedure, the gear G is inserted into the pin 4 and is rotatably supported by the pin 4. A gear (not shown) protruding on the inner periphery of a circular hole (not shown) penetrating through the center engages with an engagement groove 4a (see FIG. 8) formed on the outer periphery of the tip of the pin 4. The disconnection of the G from the pin 4 is prevented. In addition, since the front end portion (end portion on the non-fixed side) of the pin 4 is supported by the main body frame 100, the pin 4 is securely supported by both ends, and the fall of the gear G supported by the pin 4 is reliably prevented. Can be removed.

  As described above, in the present embodiment, since the lightweight resin housings 2 and 3 are used as the housing of the drive unit 1, the weight of the drive unit 1 and the cost can be reduced.

  In addition, since the pin 4 is fixed to the resin housing 2 by the insertion method instead of the conventional caulking method, the conventional caulking process is not required, and the assembling property of the drive unit 1 is improved and the number of assembling steps is reduced. Cost reduction is achieved.

  Then, a groove 8 is formed around the boss 5 formed in the resin housing 2 to form a thin cylindrical portion 5a that can be easily elastically deformed in a part of the boss 5, and is removed to the inner periphery of the thin cylindrical portion 5a. Since the retaining rib 7 protrudes over the entire circumference, the thin cylindrical portion 5a of the boss 5 is easily deformed when the pin 4 is inserted into the pin insertion hole 6 of the boss 5 and fixed. For this reason, the pin 4 can easily get over the retaining rib 7 protruding from the inner periphery of the thin cylindrical portion 5a, and the retaining rib 7 is inserted into the engaging groove 4b formed on the outer periphery of the pin 4. By engaging, the pin 4 can be reliably fixed to the resin housing 2. In this case, the retaining rib 7 protrudes from the inner periphery of the pin insertion hole 6 of the thin cylindrical portion 5a of the boss 2 over the entire circumference, so that when the pin 4 gets over the retaining rib 7, the rib 7 The stress acts uniformly on the entire surface, and excessive stress does not act locally on the rib 7. Therefore, the rib 7 is prevented from being damaged, and the occurrence of the problem that the fragments enter the resin housing 2 is prevented.

  In this embodiment, since the pin 4 is also a lightweight resin pin, the drive unit 1 can be further reduced in weight. However, a resin pin or a metal pin may be selected according to the load acting on the pin 4. For example, a high strength metal pin is used for the pin 4 on which a large load acts, and a lightweight resin pin is used on the pin 4 on which a large load does not act, thereby improving durability and reducing the weight. it can.

DESCRIPTION OF SYMBOLS 1 Drive unit 1A Main body side unit 1B Non-main body side unit 2,3 Resin housing 4 Pin 4a Engagement groove for gear removal prevention 4b Engagement groove for pin removal prevention 4c D cut of pin 5 Boss 5a Thin cylindrical part of boss 6 Pin insertion hole 6a Flat surface of pin insertion hole 7 Retaining rib 8 Groove 100 Body frame G Gear

Claims (4)

An image forming apparatus including a drive unit that is detachably attached to a main body of an image forming apparatus and is configured to rotatably support a gear train that transmits rotational power to a plurality of rollers that convey a sheet to a housing via a pin. ,
The housing is composed of a resin housing, and a groove is formed around a boss formed in the resin housing to form a thin cylindrical portion at a part of the boss, and a retaining rib is provided on the inner periphery of the thin cylindrical portion. Projecting over the entire circumference, inserting the pin into the pin insertion hole of the boss, and engaging the retaining rib formed on the thin cylindrical portion of the boss with the engaging groove formed on the outer periphery of the pin. An image forming apparatus, comprising: a drive unit that fixes the pin to the resin housing by combining.   The image forming apparatus according to claim 1, wherein the pin of the drive unit is a resin pin.   The image forming apparatus according to claim 1, wherein the pin of the drive unit is a resin pin or a metal pin according to a load applied to the pin. The image forming apparatus according to claim 1, wherein a semi-fixed side end portion of the pin of the drive unit is supported on the image forming apparatus main body side.

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