JP2000321836A - Structure for preventing gear from falling off for driving unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide structure for preventing a gear from falling off which is suitably used in an image forming device such as a copying machine, low- priced and excellent in recycling performance. SOLUTION: A fixed shaft 11 is erected on a plate-like side plate 10 made of resin, and a pawl-like projection 13 is also erected in a state where space for inserting a gear 12 is formed around the shaft 11. The projection 13 can be elastically deformed. In the case of attaching the gear 12 to the shaft 11, the projection 13 is elastically deformed so that it may not get a hindrance to attachment, and it is restored after the attachment so that the pawl part 13a of the projection 13 may be positioned on the periphery part of the gear 12 and functions as a stopper for stopping the gear 12 from falling off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear retaining structure of a drive unit suitable for use in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, or a multifunction peripheral thereof.

[0002]

2. Description of the Related Art A conventional drive unit of this type is provided with a gear train composed of a plurality of gears rotatably mounted on a fixed shaft erected on a plate-like member (hereinafter referred to as a side plate). A retaining ring such as an E-ring was attached to the shaft, or another side plate was prepared and fixed by sandwiching the gear train between the two side plates. An example of the latter is disclosed in
No. 48717 discloses a structure in which a retaining ring such as an E-ring is eliminated in order to improve recyclability (ease of disassembly), and one side plate of a drive unit is a structure of a machine main body in order to reduce costs. And a function to support one end of the fixed shaft.

FIG. 9 and FIG.
No. 8717 discloses a configuration similar to that of the drive unit. A plurality of fixed shafts 2 are provided integrally with a housing 1 which is a resin side plate, and a plurality of fixed shafts 2 constitute a gear train. Each of the gears 3... Is mounted, and is mounted on the machine body 4 in that state. Fixed shaft 2 on the machine body 4 side
A plurality of bosses 5...

[0004]

In such a drive unit, since the retaining ring such as an E-ring is eliminated as described above, the fixed shaft is not fixed when the housing 1 to which the gear 3 is attached is assembled to the machine body 4. If the gear 2 is horizontal, the gear 3 may fall off the fixed shaft 2. In order to prevent this, the assembling work must be performed while holding down the gear 3 so as not to come off, so that the workability is extremely poor.

If a groove for snap fitting is provided on the fixed shaft 2 (for example, see Japanese Patent Application Laid-Open No. Hei 10-226439), the structure of the molding die becomes complicated and the cost increases.
In addition, there is a problem that the machining accuracy of the shaft portion is adversely affected, and further, a measure against abrasion against a thrust load is required.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve these conventional problems and to provide an inexpensive and highly recyclable drive unit gear retaining structure.

[0007]

According to the first aspect of the present invention, there is provided a drive unit having a gear retaining structure, wherein a driving force is applied to a fixed shaft erected on a plate member to achieve the above object. In a gear retaining structure of a drive unit that rotatably mounts a gear for transmitting the gear and prevents the mounted gear from coming off the fixed shaft, the plate-like member is provided with a claw-like projection that can be elastically deformed. The claw portion of the claw-shaped protrusion can be locked to a peripheral portion of the gear mounted on the fixed shaft.

According to a second aspect of the present invention, the gear has a collar, and the claw of the claw-shaped projection can be locked to the collar.

According to a third aspect of the present invention, a gear for transmitting a driving force is rotatably mounted on a fixed shaft erected on a plate-like member, and the mounted gear is prevented from coming off from the fixed shaft. In the gear retaining structure of the drive unit, the plate-shaped member is provided with a claw-shaped protrusion, and the gear is provided with a collar, and the collar is provided with a notch through which the claw portion of the claw-shaped protrusion can pass. Features.

According to a fourth aspect of the present invention, the collar has an elastically deformable stopper projecting into the notch.

According to a fifth aspect of the present invention, the gear and another gear constituting a gear train together with the gear are arranged so that a thrust load of each gear of the gear train acts on the plate-like member side. It is characterized by being engaged.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of a gear retaining structure for a drive unit according to the present invention. In the figure, reference numeral 10 denotes a plate-shaped side plate made of resin. A fixed shaft 11 is provided upright on the side plate 10, and a claw-like projection is provided around the fixed shaft 11 with a space for inserting a gear 12 therebetween. 13 is also erected. The fixed shaft 11 and the claw-shaped protrusion 13 are integrally formed with the side plate 10, and the claw-shaped protrusion 13 is elastically deformable as shown by a two-dot chain line in the figure.

For this reason, when the gear 12 is to be mounted on the fixed shaft 11, the claw-like projections 13 are elastically deformed as shown in the drawing so as not to hinder the mounting. The claw portion 13a is returned so as to be positioned on the peripheral edge of the gear 12, so that the claw portion 13a functions as a stopper against the falling off of the gear 12.

It is to be noted that the side plate 10 and the claw-shaped projection 13 are not integrally formed, but, for example, the side plate 10 is made of metal and the claw-shaped projection 13 is formed of S
US or resin, or resin side plate 10
It may be a separate body such as attaching a US-made claw-shaped projection 13.

FIG. 2 is a sectional view showing a second embodiment of the present invention. The gear retaining structure of this embodiment is basically similar to that of the first embodiment of the present invention shown in FIG. 1 except that a gear 12 is provided with a collar 12a, The claw portion 13a of the projection 13 is the collar 1 of the gear 12.
The gear 12 is returned so as to be positioned above 2a so as to function as a stopper for the gear 12 falling off. The gear 12 and the collar 12a may be formed by integral molding of resin or the like. Other configurations, mounting operations, and the like are the same as those in the previous embodiment, and thus description thereof is omitted.

FIG. 3 is a sectional view showing a third embodiment of the present invention. The gear retaining structure of the present embodiment is also basically similar to the first embodiment of the present invention shown in FIG. 1, but is an example applied to a gear train including a two-stage gear. That is, the two-stage gears 14, 14 are attached to the two fixed shafts 11, 11 erected on the side plate 10 by arranging them in opposite directions as shown in the figure, and the claw-like projections 13
Is provided, and the claw portion 13a keeps it from coming off. Of course, a claw-shaped protrusion may be provided on the remaining two-stage gear 14. Other configurations, mounting operations, and the like are the same as those in the previous embodiment, and thus description thereof is omitted.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention, and FIG. 5 is a plan view of the same. This embodiment is different from the first and third embodiments in that the fixed shaft 11
This takes into account the possibility that the gear tooth surface may be damaged when inserting the gears 2 and 14. That is, in this embodiment, the gear 16 is provided with the collar 16, the notch 17 is formed in the collar 16, and the notch 17 of the collar 16 and the claw portion 18 a of the claw-shaped projection 18 are aligned as shown in FIG. The gear 15 is mounted on the fixed shaft 11. Gear 15 after insertion
Is rotated so that the claw portion 18a of the claw-shaped projection 18 presses the collar 16 of the gear 15 from above to prevent the gear 15 from coming off. By doing so, the claw-shaped projection 18 does not damage the tooth surface of the gear 15. Other configurations, mounting operations, and the like are the same as those in the previous embodiment, and thus description thereof is omitted.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention. The gear retaining structure of the present embodiment is basically similar to the third embodiment of the present invention shown in FIGS. 4 and 5, but is an example applied to a gear train including a two-stage gear. . That is, two fixed shafts 11, 1 erected on the side plate 10.
A two-stage gear 20a with a brim 19 and a two-stage gear 20b without a brim are arranged and mounted in opposite directions as shown in the figure, and a claw-like projection 21 is attached to the brim 19 of one of the two-stage gears 20a. It is provided and is prevented from falling off by the claw portion 21a. Although not shown, the flange 19 is provided with a notch. Of course, a helmet may be formed on the remaining two-stage gear 20b, and a claw-shaped projection may be provided for this.
Other configurations, mounting operations, and the like are the same as those in the previous embodiment, and thus description thereof is omitted.

In the fifth embodiment, the two-stage gear 20 is used.
When a helical gear is used for the devices a and 20b as in the device disclosed in Japanese Patent Application Laid-Open No. H10-226439, a thrust load is applied. The gap between the projection 21 and the collar 19 (the upper peripheral edge of the gear in the case of a gear without a collar) becomes small, so that the collar 19 may come into contact with the claw 21a at all times when the gear rotates. Therefore, when the helical gear is used, the two-stage gear 20a with a brim is connected to the side plate 1.
A helical gear having a torsion angle such that a load is applied in the direction of 0 may be used.

FIG. 7 is a plan view showing a sixth embodiment of the present invention. In the present embodiment, in the structures of the above-described fourth and fifth embodiments, the notches 17 provided in the collars 16 and 19 and the claw portions 18a and 21a of the claw-shaped projections 18 and 21 extremely rarely coincide with each other. At the time of assembly, the gear 1
This takes into account the possibility that 5, 20a may fall off. That is, in the present embodiment, the notch 24 formed in the collar 23 of the gear 22 is provided with a cantilevered elastically deformable locking piece 25 as a stopper as shown in the drawing, and the gear 22 is mounted on the fixed shaft 11. At this time, the locking piece 25 is deformed and assembled, and the locking piece 25 is restored after the assembly so that the notch 24 of the collar 23 and the claw of the claw-shaped projection (not shown) do not come off even if they match. It is. in this case,
If the gear 22 is made of metal, the collar 23 may be made of a leaf spring material such as SUS, and may be attached by caulking to a metal gear. Alternatively, the gear 22 and the collar 23 may be integrally formed of resin.

FIG. 8 is a plan view showing a modification of the sixth embodiment of the present invention shown in FIG. In this embodiment,
The leaf spring 26 is partially attached to the collar 23 of the gear 22 to form a locking side.

[0022]

According to the first aspect of the present invention, the gear retaining structure of the drive unit is as described above. Therefore, after the gear is mounted on the fixed shaft erected on the plate member, the plate member is inclined. However, since the gear does not fall off the fixed shaft, and there is no need for an element having a complicated shape and structure, there is an effect that a structure that is inexpensive and has excellent recyclability can be realized.

The gear retaining structure of the drive unit according to the second and third aspects is as described above. Therefore, in addition to the same effects as those of the first aspect, a gear provided on the gear is used. There is an effect that the gear can be mounted on the fixed shaft of the plate-like member without damaging the gear tooth surface.

The structure for preventing the gear from slipping out of the drive unit according to the fourth aspect is as described above. Therefore, in addition to the effect common to the third aspect, the stopper portion protruding from the notch of the gear is elastic. Since the gear is deformed, even if the notch of the gear and the claw portion of the claw-shaped projection match after the gear is mounted, there is an effect that the gear does not drop off from the fixed shaft.

Since the gear retaining structure of the drive unit according to claim 5 is as described above, in addition to the same effects as those of the above claims, the thrust load of the gear is applied to the plate-like member side. , There is an effect that the tooth surface or the brim of the gear does not come into contact with the claw portion of the claw-shaped projection after the gear is assembled to the fixed shaft.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a gear retaining structure for a drive unit according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a plan view of the same.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention.

FIG. 7 is a plan view showing a sixth embodiment of the present invention.

FIG. 8 is a plan view showing a modification of the sixth embodiment of the present invention.

FIG. 9 is a perspective view illustrating an example of a conventional gear unit retaining structure for a drive unit.

FIG. 10 is an exploded perspective view showing attachment to the machine main body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Side plate 11 Fixed shaft 12 Gear 12a Collar 13 Claw projection 13a Claw 14 Two-step gear 15 Gear 16 Collar 17 Notch 18 Claw projection 18a Claw 19 Collar 20a, 20b Two-stage gear 21 Claw projection 21a Claw 22 Gear 23 Collar 24 Notch 25 Locking piece 26 Plate spring

Claims (5)

[Claims] 1. A gear retaining structure of a drive unit for rotatably mounting a gear for transmitting a driving force to a fixed shaft erected on a plate-like member and preventing the mounted gear from falling out of the fixed shaft. The drive unit according to claim 1, wherein the plate-like member is provided with an elastically deformable claw-shaped protrusion, and the claw portion of the claw-shaped protrusion can be locked to a peripheral portion of the gear mounted on the fixed shaft. Gear retaining structure. 2. The gear retaining structure for a drive unit according to claim 1, wherein the gear has a collar, and the claw portion of the claw-shaped projection can be locked to the collar. 3. A gear retaining structure for a drive unit in which a gear for transmitting a driving force is rotatably mounted on a fixed shaft erected on a plate-shaped member, and the mounted gear is prevented from falling off from the fixed shaft. The gear of the drive unit, wherein the plate-shaped member is provided with a claw-shaped projection, the gear is provided with a collar, and the collar is provided with a notch through which a claw portion of the claw-shaped projection can pass. Retaining structure. 4. The gear retaining structure for a drive unit according to claim 3, wherein said collar has an elastically deformable stopper projecting into said notch. 5. The apparatus according to claim 1, wherein the gear and another gear forming a gear train together with the gear are meshed so that a thrust load of each gear of the gear train acts on the plate-shaped member. A gear retaining structure for a drive unit according to any one of claims 1 to 4.