Gear connection structure, drive device and image forming device

Abstract

To provide a gear connection structure capable of suppressing minute movement of a parallel pin.SOLUTION: A gear connection structure 30 comprises: a rotational shaft part 31 extending in an axial direction; a parallel pin 32 passed through a pin hole 34 that penetrates the rotational shaft part 31 in a radial direction perpendicular to the axial direction; a transmission gear 33 having an axial hole 35 through which the rotational shaft part 31 passes and a pin groove 38 into which the parallel pin 32 is inserted; and a biasing member 40 that biases the parallel pin 32 inserted into the pin groove 38 from a separation wall 38A of the pin groove 38 toward a contact wall 38B, to press it against the contact wall 38B and press it against an inner peripheral surface of the pin hole 34 on the side of the contact wall 38B.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a gear coupling structure, a drive device, and an image forming apparatus. [Background technology]

[0002] A gear coupling mechanism is known in which a metal parallel pin passed through a pin through hole in the shaft of a roller is inserted into a groove in a synthetic resin gear (Patent Document 1). A pair of protrusions is provided on one side wall of the groove on both sides of the shaft through hole through which the shaft passes. The protrusions are in close contact with the parallel pin, bringing the parallel pin into close contact with the other (opposite) side wall of the groove and also with the inner surface of the pin through hole opposite the protrusions. This suppresses vibration (microscopic movement) of the parallel pin in the pin through hole and groove. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-64111 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned technology, since the convex portion is merely a protrusion provided on the side wall of the groove, the convex portion may not contact the parallel pin with sufficient pressure due to manufacturing errors (tolerances) of the gear (groove), parallel pin, etc. Therefore, it may not be possible to properly suppress vibrations (microscopic movements) of the parallel pin in the pin-through hole or groove.

[0005] In consideration of the above circumstances, the present invention provides a gear coupling structure, a drive unit, and an image forming apparatus that are capable of suppressing minute movements of a parallel pin. [Means for solving the problem]

[0006] The gear connection structure includes a rotating shaft portion extending in the axial direction, a gear having a parallel pin passed through a pin hole that radially penetrates the rotating shaft portion perpendicular to the axial direction, an axial hole through which the rotating shaft portion passes and a pin groove into which the parallel pin is inserted, and a biasing member that biases the parallel pin inserted into the pin groove from a separation wall, which is one of a pair of wall portions of the pin groove, toward a contact wall, which is the other wall portion, and presses the parallel pin against the contact wall and against the inner surface of the pin hole on the contact wall side.

[0007] In this case, the pin groove is formed to extend on both sides in the radial direction from the axial hole, and the biasing member is provided upstream in the rotational direction of the gear at a position away from the axial hole in one radial direction, and biases the parallel pin toward the downstream side in the rotational direction.

[0008] In this case, the biasing member may have an elastic portion that is molded integrally with the gear, is disposed between the parallel pin and the separating wall, and contacts the parallel pin with an elastic force.

[0009] In this case, the biasing member may be a leaf spring disposed in a compressed state between the parallel pin and the separating wall.

[0010] In this case, the biasing member may be a coil spring disposed in a compressed state between the parallel pin and the separating wall.

[0011] The drive device includes the above-mentioned gear coupling structure and a drive portion that rotates the rotating shaft portion.

[0012] The image forming apparatus includes the above-mentioned drive device. Effect of the Invention

[0013] According to the present invention, minute movements of the parallel pins can be suppressed. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram (front view) showing an internal structure of an image forming apparatus according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing a drive device according to an embodiment of the present invention. [Diagram 3] 1 is a perspective view showing a drive device according to an embodiment of the present invention; [Figure 4] 1 is a front view showing a gear coupling structure according to an embodiment of the present invention; [Diagram 5] FIG. 5 is a cross-sectional view of FIG. 4 . [Figure 6] FIG. 4 is a cross-sectional view showing a gear coupling structure according to a first modified example of an embodiment of the present invention. [Figure 7] FIG. 11 is a perspective view showing a gear coupling structure according to a second modified example of the embodiment of the present invention. [Figure 8] FIG. 11 is a front view showing a gear coupling structure according to a second modified example of the embodiment of the present invention. [Figure 9] 9 is a cross-sectional view taken along line IX-IX of FIG. 8. [Figure 10] FIG. 11 is a front view showing a gear coupling structure according to a third modified example of the embodiment of the present invention. [Figure 11] 11 is a cross-sectional view taken along the line XI-XI of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Note that Fr, Rr, L, R, U, and D shown in the drawings indicate front, rear, left, right, top, and bottom. Terms indicating directions and positions are used in this specification, but these terms are used for convenience of explanation and do not limit the technical scope of the present invention.

[0016] [Image forming equipment] The image forming apparatus 1 will be described with reference to Fig. 1. Fig. 1 is a schematic diagram (front view) showing the internal structure of the image forming apparatus 1.

[0017] The image forming apparatus 1 includes an apparatus main body 2 having a generally rectangular parallelepiped exterior. A paper feed cassette 3 that stores paper P (medium) is removably provided at the bottom of the apparatus main body 2, and a paper output tray 4 is provided on the top surface of the apparatus main body 2. A toner container 5 that stores, for example, black toner (developer) is provided at the upper left of the apparatus main body 2.

[0018] Inside the device body 2, a transport path 6 and a reversing transport path 7 are formed as paths for transporting the paper P. The transport path 6 is a path formed in a substantially S-shape for transporting the paper P from the paper feed cassette 3 to the paper output tray 4. The reversing transport path 7 branches downward on the downstream side of the transport path 6, extends to the left, and merges with the upstream side of the transport path 6. The reversing transport path 7 is a path for reversing the paper P and transporting it again to the imaging unit 8 described below. In addition, in the description of the image forming device 1, the terms "upstream, midstream, downstream" refer to "upstream, midstream, downstream" in the transport direction of the paper P (medium).

[0019] The image forming apparatus 1 includes an image forming unit 8 that forms an image on a sheet of paper P by an electrophotographic method. The image forming unit 8 includes a photoconductor drum 10, a charging device 11, a developing device 12, a transfer roller 13, an optical scanning device 14, and a fixing device 15.

[0020] The photosensitive drum 10 (rotating body) is provided in the middle of the transport path 6. The photosensitive drum 10 is formed into a cylindrical shape that is long in the front-rear direction by laminating a photosensitive layer on the outer circumferential surface of a metal tube. The drum shaft 10A (see FIG. 2 described later) of the photosensitive drum 10 is supported rotatably about its axis by a pair of supporting metal plates (not shown) arranged on both the front and rear sides.

[0021] A paper feed unit 16 is provided at the upstream end of the transport path 6, and a pair of registration rollers 17 is provided in the midstream portion of the transport path 6 (upstream of the photoconductor drum 10). The charging device 11, the developing device 12, and the transfer roller 13 are arranged around the photoconductor drum 10 in the order of the image formation process. The transfer roller 13 contacts the photoconductor drum 10 from below to form a transfer nip. The optical scanning device 14 is provided above the photoconductor drum 10. The fixing device 15 is provided on the downstream side of the transport path 6.

[0022] The image forming apparatus 1 is provided with a control unit (not shown) for appropriately controlling various devices to be controlled. The control unit includes a processor and the like that executes various arithmetic processing according to programs and parameters stored in a memory. The image forming apparatus 1 is also provided with a display input unit (not shown) such as a touch panel and buttons for inputting various instructions from a user (operator). The display input unit is electrically connected to the control unit, and transmits input signals to the control unit and receives electrical signals (for example, display information on a touch panel) from the control unit.

[0023] [Image formation processing] The following describes the operation of the image forming apparatus 1. The control unit executes image forming processing as follows, based on image data input from an external terminal, for example.

[0024] The charging device 11 charges the surface of the photosensitive drum 10, and the optical scanning device 14 emits scanning light based on image data to form an electrostatic latent image on the surface (photosensitive layer) of the photosensitive drum 10. The developing device 12 develops a toner image on the surface of the photosensitive drum 10 using toner supplied from the toner container 5. The paper feed section 16 sends out paper P from the paper feed cassette 3 one sheet at a time to the conveying path 6. The paper P is conveyed along the conveying path 6, skew-corrected by a pair of registration rollers 17, and enters the transfer nip. The transfer roller 13 transfers the toner image on the photosensitive drum 10 to the paper P passing through the transfer nip, and the fixing device 15 thermally fixes the toner image to the paper P. In the case of single-sided printing, the paper P is discharged to the paper output tray 4.

[0025] In the case of double-sided printing, the paper P is switched back at the downstream end of the conveying path 6, conveyed along the reversing conveying path 7, and returned to the conveying path 6. Thereafter, an image is formed on the back side of the paper P through the same process as above, and the double-sided printed paper P is discharged to the paper output tray 4.

[0026] [Drive system] The driving device 18 will be described with reference to Fig. 2 to Fig. 5. Fig. 2 is a plan view showing the driving device 18. Fig. 3 is a perspective view showing the driving device 18. Fig. 4 is a front view showing the gear coupling structure 30. Fig. 5 is a VV sectional view of Fig. 4.

[0027] 2, the image forming apparatus 1 is provided with a drive device 18 that rotates the photoconductor drum 10. The drive device 18 is disposed behind the photoconductor drum 10. The drive device 18 has a drive unit 20 and a gear coupling structure 30.

[0028] <Drive unit> The driving unit 20 is, for example, a direct current motor, and is electrically connected to and driven by a control unit that controls the image forming apparatus 1. As shown in FIG. 2 and FIG. 3, the driving unit 20 has a driving body 21 that incorporates a stator and a rotor (not shown), and a driving shaft 22 that extends from the axis of the rotor. The driving body 21 is fixed to the rear surface of the driving sheet metal 23. The driving shaft 22 is formed in a cylindrical shape (round bar shape) and is supported by the driving body 21 via a bearing (not shown) so as to be rotatable about its axis. The driving shaft 22 passes through a hole (not shown) opened in the driving sheet metal 23 and protrudes forward of the driving sheet metal 23. A pinion gear 24 that meshes with an intermediate gear 25 is fixed to the tip of the driving shaft 22. The intermediate gear 25 is, for example, a stepped gear, and the pinion gear 24 is, for example, a spur gear that meshes with a large diameter portion of the intermediate gear 25. The intermediate gear 25 is fixed to an intermediate shaft 26 that is supported by a metal plate (not shown) so as to be rotatable about its axis.

[0029] <Gear connection structure> As shown in Fig. 2, the gear connection structure 30 connects the drive unit 20 and the photosensitive drum 10, and transmits the drive force (rotational force) of the drive unit 20 to the photosensitive drum 10. As shown in Fig. 2 to Fig. 5, the gear connection structure 30 includes a rotation shaft portion 31, a parallel pin 32, and a transmission gear 33 (gear).

[0030] (Rotating shaft) The rotating shaft portion 31 is formed, for example, from a metal material in the shape of a round bar extending in the front-rear direction (axial direction). The rotating shaft portion 31 is supported by a metal plate (not shown) so as to be rotatable about its axis. The rotating shaft portion 31 is disposed substantially coaxially with the drum shaft 10A of the photosensitive drum 10, and the front end of the rotating shaft portion 31 is connected to the rear end of the drum shaft 10A via a coupling 27 (see FIG. 2). A pin hole 34 (see FIG. 4) is formed on the rear side of the rotating shaft portion 31. The pin hole 34 is a round hole that penetrates the rotating shaft portion 31 in a radial direction perpendicular to the axial direction.

[0031] (Parallel pin) As shown in Fig. 4, the parallel pin 32 is formed, for example, from a metal material in the shape of a round bar, and is passed through a pin hole 34 of the rotating shaft portion 31. The parallel pin 32 passed through the pin hole 34 extends approximately evenly on both sides in the radial direction from the rotating shaft portion 31. The inner diameter of the pin hole 34 is slightly larger than the diameter (outer diameter) of the parallel pin 32, and a small gap is formed between the inner peripheral surface of the pin hole 34 and the outer peripheral surface of the parallel pin 32 (see Fig. 4).

[0032] (Transmission gear) The transmission gear 33 is, for example, made of synthetic resin, and is a spur gear that meshes with the small diameter portion of the intermediate gear 25 (see FIG. 2). A pair of cylindrical portions 36 extending in the front-rear direction (axial direction) are formed at the axial center of the transmission gear 33 (see FIGS. 3 and 5). A shaft hole 35 is formed in the pair of cylindrical portions 36 (transmission gear 33) through which the rear side of the rotating shaft portion 31 passes (see FIGS. 3 and 4). The shaft hole 35 is a round hole that passes through the transmission gear 33 in the axial direction. As shown in FIGS. 3 to 5, a pair of slits 37 are cut into both radial sides of the front cylindrical portion 36. The inner diameter of the shaft hole 35 is slightly larger than the diameter (outer diameter) of the rotating shaft portion 31, and a small gap is formed between the inner peripheral surface of the shaft hole 35 and the outer peripheral surface of the rotating shaft portion 31 (not shown).

[0033] As shown in FIG. 3 to FIG. 5, the transmission gear 33 is formed with a pin groove 38 into which the parallel pin 32 is inserted. The pin groove 38 is formed on the front surface of the transmission gear 33 so as to extend from the shaft hole 35 (cylindrical portion 36) to both sides in the radial direction. In other words, the pin groove 38 is divided into two equal parts in the radial direction by the cylindrical portion 36. In detail, the pin groove 38 corresponds to the edge portions of the pair of slits 37 of the cylindrical portion 36, and is formed between a pair of wall portions 38A, 38B protruding forward from the front surface of the transmission gear 33. Both ends in the radial direction of the pair of wall portions 38A, 38B are connected by an end wall 38C. The pair of wall portions 38A, 38B are connected to the cylindrical portion 36, and the pin groove 38 is continuous with the slit 37. The pin groove 38 and the slit 37 are formed with approximately the same width. The width of the pin groove 38 and the slit 37 is slightly larger than the diameter (outer diameter) of the parallel pin 32, and a small gap is formed between the inner surface of the pin groove 38 (a pair of wall portions 38A, 38B) or the slit 37 and the outer peripheral surface of the parallel pin 32 (see Figure 4).

[0034] [Procedure for connecting the transmission gear to the rotating shaft] Here, a procedure for connecting the transmission gear 33 to the rotating shaft portion 31 will be briefly described. The parallel pin 32 is passed through a pin hole 34 of the rotating shaft portion 31, and the rear portion of the rotating shaft portion 31 is inserted from the front into a cylindrical portion 36 (shaft hole 35) of the transmission gear 33. The parallel pin 32 passes through a slit 37 of the cylindrical portion 36 and fits into a pin groove 38. A retaining member (not shown) such as a C-ring is attached to the rotating shaft portion 31 to restrict movement of the transmission gear 33 in the axial direction. As a result, the driving portion 20 is connected to the photosensitive drum 10 via the gear connection structure 30, and the rotating shaft portion 31 and the photosensitive drum 10 can be rotated.

[0035] As described above, there is a small gap between the inner peripheral surface of the pin hole 34 and the outer peripheral surface of the parallel pin 32, and there is also a small gap between the inner surfaces of the pair of wall parts 38A, 38B and the outer peripheral surface of the parallel pin 32 (see FIG. 4). Therefore, when the rotating shaft part 31 is rotated by the driving part 20, the rotating shaft part 31 rotates freely within the small gap between the pin hole 34 and the parallel pin 32. In addition, the parallel pin 32 starts to rotate later than the rotating shaft part 31, and rotates freely within the small gap between the pin groove 38. In other words, due to these gaps, there is a risk that the rotational force of the rotating shaft part 31 cannot be efficiently transmitted to the transmission gear 33. Furthermore, when the parallel pin 32 collides with the inner peripheral surface of the pin hole 34 or the inner surfaces of the wall parts 38A, 38B that form the pin groove 38, an unpleasant impact sound may be generated.

[0036] Therefore, the gear coupling structure 30 according to this embodiment includes a biasing member 40 that biases the parallel pin 32 inserted into the pin groove 38 from one wall portion 38A toward the other wall portion 38B. In this specification, one wall portion 38A of the pair of walls 38A, 38B of the pin groove 38 may be referred to as the "separation wall 38A" and the other wall portion 38B may be referred to as the "contact wall 38B."

[0037] (urging member) As shown in Figs. 3 to 5, the biasing member 40 is integrally molded on the front surface (separation wall 38A) of the transmission gear 33. The biasing member 40 is, for example, a so-called snap-fit ​​type member formed of an elastically deformable synthetic resin material. The biasing member 40 is provided on the separation wall 38A at a position radially away from the shaft hole 35 and upstream of the rotation direction (see the arrow shown in Fig. 4) of the transmission gear 33. The biasing member 40 is formed in a substantially V-shape (or substantially U-shape) that straddles the separation wall 38A when viewed from the outside in the radial direction (see Fig. 5). The biasing member 40 has an elastic portion 40A that extends from the tip (front end) of the V-shape toward the inside of the pin groove 38. When the parallel pin 32 is not inserted into the pin groove 38, the elastic portion 40A is formed to narrow the width of the pin groove 38 (the distance between the pair of wall portions 38A, 38B). In other words, the distance between the elastic portion 40A and the contact wall 38B is smaller than the outer diameter of the parallel pin 32.

[0038] In the process of inserting the parallel pin 32 into the pin groove 38, the elastic portion 40A is compressed (elastically deformed) toward the separation wall 38A side (outside the pin groove 38) while contacting the parallel pin 32. The elastic portion 40A is disposed between the parallel pin 32 inserted into the pin groove 38 and the separation wall 38A, and contacts the parallel pin 32 with elastic force. The biasing member 40 (elastic portion 40A) biases the parallel pin 32 inserted into the pin groove 38 toward the downstream side in the rotation direction (at the position of the biasing member 40), and presses the parallel pin 32 against the contact wall 38B and against the inner peripheral surface of the pin hole 34 on the contact wall 38B side (see FIGS. 4 and 5).

[0039] In the gear coupling structure 30 according to the present embodiment described above, the parallel pin 32 inserted into the pin groove 38 is biased by the biasing member 40 to be pressed against the contact wall 38B and the inner circumferential surface of the pin hole 34. With this configuration, the parallel pin 32 can be kept in contact with the contact wall 38B and the inner circumferential surface of the pin hole 34, so that minute movement (vibration) of the parallel pin 32 in the pin groove 38 can be suppressed. This allows the rotational force of the rotating shaft portion 31 to be efficiently transmitted to the transmission gear 33. In addition, the parallel pin 32 is prevented from colliding with the inner circumferential surface of the pin hole 34 and the pair of walls 38A, 38B, so that the generation of harsh impact noise can be suppressed.

[0040] Furthermore, according to the gear coupling structure 30 of this embodiment, the parallel pin 32 is pressed against the contact wall 38B, which is downstream in the rotation direction, at a position facing the biasing member 40, so that the rotating shaft portion 31 and the parallel pin 32 can rotate as a unit. This allows the rotational force to be transmitted to the transmission gear 33 efficiently.

[0041] In addition, in the gear coupling structure 30 according to this embodiment, the elastic portion 40A of the biasing member 40 integrally molded with the transmission gear 33 is arranged between the parallel pin 32 and the separation wall 38A and contacts the parallel pin 32 with elastic force. With this configuration, the parallel pin 32 can be pressed against the contact wall 38B and the inner peripheral surface of the pin hole 34 simply by inserting the parallel pin 32 into the pin groove 38.

[0042] In the gear coupling structure 30 according to the present embodiment, the biasing member 40 is formed in a substantially V-shape when viewed from the outside in the radial direction, but the present invention is not limited to this. For example, as shown in Fig. 6, the biasing member 41 may be formed in a substantially N-shape when viewed from the outside in the radial direction (first modified example). The elastic portion 41A of the biasing member 41 is formed in a substantially V-shape when viewed from the outside in the radial direction, and a claw portion 41B that restricts the parallel pin 32 from coming off the pin groove 38 may be formed on the free end side of the elastic portion 41A.

[0043] In addition, in the gear coupling structure 30 according to the present embodiment (including the first modified example), the urging members 40, 41 are integrally molded with the transmission gear 33, but the present invention is not limited to this. The urging members 40, 41 may be separate members from the transmission gear 33, and may be attached to the transmission gear 33 (separation wall 38A) after the parallel pin 32 is inserted into the pin groove 38 (not shown).

[0044] In the gear coupling structure 30 according to the present embodiment (including the first modified example), the biasing members 40 and 41 are so-called snap-fit ​​members, but the present invention is not limited thereto. For example, as shown in Figs. 7 to 9, the biasing member 42 may be a leaf spring arranged in a compressed state between the parallel pin 32 and the separation wall 38A (second modified example). The biasing member 42 is formed, for example, by bending a metal plate. The biasing member 42 has a biasing main body portion 42B (including an elastic portion 42A) formed in a substantially U-shape straddling the separation wall 38A when viewed from the outside in the radial direction, and a fixed piece portion 42C bent relative to the biasing main body portion 42B and fixed to the front surface of the transmission gear 33 by a screw or the like (see Fig. 9).

[0045] 10 and 11, the biasing member 43 may be a coil spring arranged in a compressed state between the parallel pin 32 and the separating wall 38A (third modification). In this case, the separating wall 38A may be bent to ensure a space for arranging the biasing member 43. In addition, to facilitate the insertion of the parallel pin 32 into the pin groove 38, a contact 43A having a slope for guiding the insertion of the parallel pin 32 may be fixed to the tip of the biasing member 43.

[0046] In the gear coupling structure 30 according to the present embodiment (including the first to third modified examples, the same applies below), the rotating shaft portion 31 is coupled to the photosensitive drum 10, but the present invention is not limited to this. Instead of the photosensitive drum 10, the rotating shaft portion 31 can be coupled to a rotating body that rotates around an axis, such as a developing roller (not shown) of the developing device 12 or a fixing roller (not shown) of the fixing device 15.

[0047] Furthermore, the image forming apparatus 1 according to the present embodiment is a monochrome printer, but is not limited thereto and may be a color printer, a copy machine, a facsimile, etc. Furthermore, the image forming method of the image forming apparatus 1 is an electrophotographic type, but is not limited thereto and may be an inkjet type.

[0048] The above embodiment is merely an example of the gear coupling structure, drive device, and image forming apparatus according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. The present invention may be modified, substituted, or altered in various ways without departing from the spirit of the technical concept, and the claims include all embodiments that may be included within the scope of the technical concept. [Explanation of symbols]

[0049] 1. Image forming device 20 Drive unit 30 Gear connection structure 31 Rotating shaft 32 Parallel pin 33 Transmission gear (gear) 34 Pin Hole 35 Shaft hole 38 Pin groove 38A Separation wall (wall) 38B Contact wall (wall part) 40, 41, 42, 43 Pressing member 40A, 41A, 42A Elastic part

Claims

1. A rotating shaft portion extending in an axial direction; a parallel pin that is inserted into a pin hole that penetrates the rotating shaft portion in a radial direction perpendicular to the axial direction; a gear having a shaft hole through which the rotating shaft portion passes and a pin groove into which the parallel pin is inserted; a biasing member that biases the parallel pin inserted into the pin groove from a separation wall, which is one of a pair of wall portions of the pin groove, toward a contact wall, which is the other wall portion, and presses the parallel pin against the contact wall and against an inner peripheral surface of the pin hole facing the contact wall.

2. The pin groove is formed to extend from the shaft hole to both sides in the radial direction, 2. The gear coupling structure according to claim 1, wherein the biasing member is provided on the upstream side in the rotation direction of the gear at a position away from the shaft hole in one radial direction, and biases the parallel pin toward the downstream side in the rotation direction.

3. 3. The gear coupling structure according to claim 1, wherein the biasing member has an elastic portion that is molded integrally with the gear, is disposed between the parallel pin and the separating wall, and contacts the parallel pin with an elastic force.

4. 3. The gear coupling structure according to claim 1, wherein the biasing member is a leaf spring disposed in a compressed state between the parallel pin and the separating wall.

5. 3. The gear coupling structure according to claim 1, wherein the biasing member is a coil spring disposed in a compressed state between the parallel pin and the separating wall.

6. A gear coupling structure according to claim 1 or 2; a drive unit that rotates the rotating shaft unit.

7. An image forming apparatus comprising the drive device according to claim 6.

Images