JP2003139221A - Gear mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear mounting structure which positively prevents a gear from being dropped from a shaft even if axial stress is applied to the gear. SOLUTION: This gear mounting structure comprises a first groove section 3a formed at the front end of the shaft 3, a rib 1f which is positioned in a shaft insertion hole 1c of the gear 1, engages with a first groove 3a on the shaft 3, and which has a rotative detent function of the gear 1 against the shaft 3, and a pair of hooks 1d which are formed at the outer periphery of a shell 1b of the gear 1, engage with the side of a bearing 2, and which have a dropoff detent function of the gear 1 against the bearing 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear mounting structure, and more particularly to a gear having a gear portion, a body portion, and a shaft insertion hole, and a body portion insertion hole into which the body portion of the gear is inserted. The present invention relates to a gear mounting structure including a bearing that rotatably supports the gear and a shaft that is inserted into a shaft insertion hole of the gear.

[0002]

2. Description of the Related Art Conventionally, a structure in which a gear is fixed to a shaft is used in a paper feeding roller, a paper discharging roller and the like of a printer. In such a structure, it is required to prevent the gear from coming off the shaft.

Therefore, conventionally, various structures have been proposed in order to prevent the gears from coming off from the shaft. These are disclosed, for example, in JP-A-8-281826, JP-A-5-19716 and JP-A-9-30353.
No. 5, for example.

The above-mentioned Japanese Patent Laid-Open Publication No. 8-281826 discloses
A structure is provided in which a groove is provided along the outer periphery of the shaft near the tip of the shaft (shaft), and a hook that engages with the groove of the shaft is provided in the gear (composite gear) to prevent the gear from coming off the shaft. Has been done.

Further, in Japanese Utility Model Laid-Open No. 5-19716, a hook is provided near the tip of a shaft (rotating shaft) along the outer circumference of the shaft, and a hook that engages with the groove of the shaft on the gear (gear) side. A structure for preventing the gear from coming off from the shaft by providing the (arm piece) is disclosed. Further, in this structure, the gear is prevented from rotating with respect to the shaft by attaching the stop pin to the shaft and providing the groove corresponding to the stop pin on the gear side.

Further, in the above-mentioned Japanese Patent Laid-Open No. 9-303535, in a structure in which a gear (rotating part) is rotatably attached to a frame chassis (chassis), in order to prevent the gear from coming off from the frame chassis, A structure in which a hook (claw) is provided on a gear is disclosed.

[0007]

However, the above-mentioned Japanese Unexamined Patent Publication (Kokai) No. Hei 8
In the conventional gear mounting structures disclosed in Japanese Patent No. 281826 and Japanese Utility Model Laid-Open No. 5-19716, fixing of the gear and the shaft in the axial direction is performed by engaging a hook formed on the gear with a groove formed on the shaft. Since it is performed only by, the hook easily bends upward when axial stress is applied. Therefore, there is a problem that the gear easily comes off the shaft when an axial stress is applied.

Further, in the gear mounting structure disclosed in Japanese Utility Model Laid-Open No. 5-19716, since the stop pin is used to prevent the gear from rotating with respect to the shaft, the number of parts and the number of assembling steps increase accordingly. There is also a problem.

Also in the conventional gear mounting structure disclosed in Japanese Patent Laid-Open No. 9-303535, the above-mentioned Japanese Patent Laid-Open No. 8-281826 and Japanese Utility Model Laid-Open No. 5-197.
Similar to the gear mounting structure in Japanese Patent No. 16,
There is a problem that the gear easily comes off from the frame chassis when stress is applied in the axial direction.

The present invention has been made to solve the above problems, and one object of the present invention is to:
It is an object of the present invention to provide a gear mounting structure capable of reliably preventing the gear from falling off the shaft even when stress is applied to the gear in the axial direction.

Another object of the present invention is to reduce the number of parts and the number of assembling steps in the above gear mounting structure.

[0012]

According to a first aspect of the present invention, there is provided a gear mounting structure comprising a gear having a gear portion, a body portion, and a roller shaft insertion hole, and a body portion insertion hole into which the body portion of the gear is inserted. In a gear mounting structure of a printer including a bearing that rotatably supports a gear, a frame chassis for mounting the bearing, and a roller shaft that is inserted into a roller shaft insertion hole of the gear, the bearing is provided at a tip portion of the roller shaft. The first groove portion, a rib integrally provided with the gear in the roller shaft insertion hole of the gear, engaged with the first groove portion of the roller shaft, and having a function of preventing the gear from rotating with respect to the roller shaft, and a rib of the body of the gear. It is provided integrally with the gear on the outer periphery so as to project outward, engages with the side surface of the bearing, and removes the gear from the bearing. A pair of hooks having a tapered front surface having a locking function and a hook provided on the body of the gear, and a portion of the body of the gear where the hook is provided can be flexibly deformed toward the inner peripheral side of the body of the gear. And a second groove portion.

According to the first aspect of the present invention, as described above, the pair of hooks having the function of preventing the gear from slipping off from the bearing are provided on the outer peripheral portion of the body of the gear, so that the body of the gear is inserted into the body body insertion hole. After fitting, the hook can prevent the gear from coming off the bearing. Especially, after the roller shaft is inserted into the roller shaft insertion hole of the gear, the outer circumferential surface of the roller shaft prevents the hook from bending toward the inner peripheral side of the body of the gear. Even if it is added, it is possible to reliably prevent the gear from coming off the bearing.
As a result, it is possible to reliably prevent the gear from slipping off the roller shaft even when stress is applied to the gear in the axial direction. Further, by providing the gear body with a second groove for flexibly deforming the portion of the gear body where the hook is provided to the inner peripheral side of the gear body, the body of the gear is not Since the hook flexes and deforms when it is inserted into the body portion insertion hole, the body portion of the gear can be easily inserted into the body portion insertion hole of the bearing. Also, by tapering the front surface of the hook, the hook becomes easier to bend toward the inner peripheral side of the gear when the body of the gear is inserted into the body body insertion hole of the bearing. The part can be inserted into the body insertion hole of the bearing.

Further, according to the first aspect of the present invention, as described above, the first groove portion is provided at the tip end portion of the roller shaft, the first groove portion is engaged with the roller shaft, and the rotation preventing function of the gear with respect to the roller shaft is prevented. By providing the ribs provided on the bottom surface of the roller shaft insertion hole of the gear, it is possible to prevent the roller shaft from rotating with respect to the gear. Further, by forming the hook and the rib integrally with the gear, it is possible to reduce the number of parts and the number of assembling steps as compared with the case where the hook and the rib are formed as separate parts from the gear.

According to a second aspect of the present invention, there is provided a gear mounting structure including a gear having a gear portion, a body portion, and a shaft insertion hole, and a body portion insertion hole into which the body portion of the gear is inserted, and rotatably supporting the gear. In a gear mounting structure including a bearing and a shaft inserted into a shaft insertion hole of a gear, a first groove portion provided in a tip end portion of the shaft and a first groove portion provided in the shaft insertion hole of the gear and engaged with the first groove portion of the shaft. A rib having a function of preventing rotation of the gear with respect to the shaft, and a hook provided on the outer peripheral portion of the body of the gear and engaging with a side surface of the bearing and having a function of preventing the gear from slipping out of the bearing. ing.

According to the second aspect of the present invention, as described above, the hook having the function of preventing the gear from slipping off the bearing is provided on the outer peripheral portion of the body of the gear, so that the body of the gear is fitted in the hole for inserting the body. After that, the hook can prevent the gear from coming off the bearing. In particular, after the shaft is inserted into the shaft insertion hole of the gear, the outer peripheral surface of the shaft prevents the hook from flexing toward the inner peripheral side of the gear body, so when axial stress is applied to the gear. Moreover, it is possible to reliably prevent the gear from coming off the bearing. As a result, even when an axial force is applied to the gear, it is possible to reliably prevent the gear from falling off the shaft. In addition, by providing a first groove portion at the tip end portion of the shaft, and by providing a rib that engages with the first groove portion of the shaft and has a function of preventing rotation of the gear with respect to the roller shaft on the bottom surface of the shaft insertion hole of the gear, The shaft can be prevented from rotating with respect to the gear.

According to a third aspect of the present invention, in the gear mounting structure according to the second aspect, the rib is integrally formed with the gear. According to this structure, the number of parts and the number of assembling steps can be reduced as compared with the case where the rib and the gear are formed as separate parts.

A gear mounting structure according to a fourth aspect is the structure of the second or third aspect, in which the hook is formed integrally with the gear. According to this structure, the number of parts and the number of assembling steps can be reduced as compared with the case where the hook is formed as a separate part from the gear.

According to a fifth aspect of the present invention, in the gear mounting structure according to any one of the second to fourth aspects, the portion provided on the body of the gear and the hook of the body of the gear is provided on the inner circumference of the body of the gear. The second groove portion is further provided on the side of the portion so as to be flexibly deformable. When the body portion of the gear is inserted into the body portion insertion hole of the bearing, the hook is bent and deformed, so that the body portion of the gear can be easily inserted into the body portion insertion hole of the bearing.

According to a sixth aspect of the present invention, in the gear mounting structure according to any one of the second to fifth aspects, the front surface of the hook has a tapered shape. With this configuration,
When inserting the body part of the gear into the body part insertion hole of the bearing,
Since the hook is more easily bent toward the inner peripheral portion of the gear, the body of the gear can be inserted into the body insertion hole of the bearing more easily.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing a gear mounting structure according to a first embodiment of the present invention.
FIG. 2 is an exploded perspective view of the gear mounting structure according to the first embodiment shown in FIG. FIG. 3 is a front view of the gear portion of the gear attachment structure according to the first embodiment shown in FIG. 1 as seen from the roller shaft insertion direction.

The gear mounting structure of the first embodiment of the present invention will be described below with reference to FIGS. In addition, in the first embodiment, a gear mounting structure in the discharge roller portion of the printer will be described. As shown in FIGS. 1 and 2, the gear mounting structure of the first embodiment includes a resin gear 1, a resin bearing 2, and a metal hollow roller shaft 3.

The gear 1 includes a gear portion 1a, a body portion 1b, a roller shaft insertion hole 1c, a pair of hooks 1d, and a second portion.
The groove portion 1e and the rib 1f are included. A pair of hooks 1
The d is integrally provided with the gear 1 so as to project outward on the outer peripheral portion of the body portion 1b of the gear 1. The hook 1d engages with the side surface of the bearing 2 and has a function of preventing the gear 1 from coming off from the bearing 2. The front surface of the hook 1d has a tapered shape. The outer diameter of the tapered tip of the hook 1d is equal to that of the bearing 2
It is formed to be smaller than the inner diameter of the body insertion hole 2a. The second groove portion 1e is the hook 1 of the body portion 1b.
A portion including d is provided to allow the body portion 1b to be flexibly deformed toward the inner peripheral portion side.

The rib 1f is provided integrally with the gear 1 in the roller shaft insertion hole 1c. This rib 1f is
By engaging with the first groove portion 3a at the tip portion of the roller shaft 3, it has a function of preventing the gear 1 from rotating with respect to the roller shaft 3. Although not shown, the end surface of the inner peripheral portion of the roller shaft insertion hole 1c of the gear 1 also has a roller shaft 3
Is tapered for easy insertion.

The bearing 2 has a body insertion hole 2a.
And a hook-shaped protrusion 2b. The body insertion hole 2a is provided to rotatably support the body 1b of the gear 1. The hook-shaped protrusion 2 b has a hook shape and is provided to fix the bearing 2 to the frame chassis 4. By engaging the hook-shaped protrusion 2b with an opening (not shown) formed in the frame chassis 4, the bearing 2
Are fixed to the frame chassis 4.

The bearing 5 is fixed to the frame chassis 4 and has a recess 5a for rotatably supporting the roller shaft 3, as shown in FIG. The bottom surface of the recess 5a prevents one end of the roller shaft 3 from coming off in the axial direction.

In the gear mounting structure according to the first embodiment, as described above, the pair of hooks 1d having the function of preventing the gear 1 from coming off the bearing 2 are attached to the body portion 1b of the gear 1.
It is possible to prevent the gear 1 from coming off the bearing 2 by the hook 1d after the body portion 1b of the gear 1 is fitted into the body portion insertion hole 2a of the bearing 2 by being provided on the outer peripheral portion. Especially, after inserting the roller shaft 3 into the roller shaft insertion hole 1c of the gear 1, the hook 1
Since the outer peripheral surface of the roller shaft 3 prevents the inner peripheral side of the body 1b of the gear 1 from being bent, the outer peripheral surface of the roller shaft 3 prevents the gear 1 from coming out of the bearing 2 even when an axial stress is applied to the gear 1. Can be reliably prevented. As a result, it is possible to reliably prevent the gear 1 from slipping out of the roller shaft 3 even when an axial stress is applied to the gear 1.

In the gear mounting structure according to the first embodiment, the hook 1d and the rib 1f are formed integrally with the gear 1 as described above, so that the hook 1d and the rib 1f are separate parts from the gear 1. The number of parts and the number of assembling steps can be reduced as compared with the case where they are formed.

Next, with reference to FIGS. 1 to 3, a method of assembling the gear mounting structure in the first embodiment will be described.

First, from the state shown in FIG. 2, the body portion 1b of the gear 1 is inserted into the body portion insertion hole 2a of the bearing 2. In this case, since the outer diameter of the tapered tip of the hook 1d is smaller than the inner diameter of the body insertion hole 2a of the bearing 2, the body 1b of the gear 1 is inserted into the body 2 of the bearing 2. When the hook 1d is inserted into the hole 2a, the tapered portion of the hook 1d is pressed by the inner peripheral side end of the body insertion hole 2a of the bearing 2. This makes the hook 1d
Is bent and deformed toward the roller shaft insertion hole 1c,
The body portion 1b of the gear 1 can be easily inserted into the body portion insertion hole 2a of the bearing 2. Then, with the gear 1 completely inserted in the bearing 2, the stress applied to the hook 1d from the inner peripheral portion of the body insertion hole 2a of the bearing 2 disappears, so as shown in FIG. It recovers to its original shape. As a result, the hook 1d engages with the side surface of the bearing 2, so that the gear 1 is axially fixed to the bearing 2.

Thereafter, the roller shaft 3 is inserted into the roller shaft insertion hole 1c of the gear 1, and at the same time, the first groove portion 3a provided at the tip of the roller shaft 3 and the roller shaft insertion hole 1c of the gear 1 are provided. The rib 1f is engaged. As a result, the gear 1 becomes the roller shaft 3
It is fixed so that it does not rotate against.

(Second Embodiment) FIG. 4 is a sectional view showing a gear mounting structure according to a second embodiment of the present invention.
FIG. 5 is an exploded perspective view of the gear mounting structure according to the second embodiment shown in FIG. FIG. 6 is a front view of the gear portion of the gear attachment structure according to the second embodiment shown in FIG. 4, as seen from the direction opposite to the roller shaft insertion direction. The second embodiment shows an example in which the mounting direction of the gear and the bearing is opposite to that of the first embodiment.

The gear mounting structure according to the second embodiment of the present invention will be described below with reference to FIGS. In addition, in the second embodiment, a gear mounting structure in the discharge roller portion of the printer will be described. As shown in FIGS. 4 and 5, the gear mounting structure of the second embodiment includes a resin gear 11, a resin bearing 12, and a metal hollow roller shaft 13.

The gear 11 includes a gear portion 11a and a body portion 11b.
, Roller shaft insertion hole 11c, and a pair of hooks 11
It includes d, the second groove portion 11e, and the rib 11f.
The pair of hooks 11d are provided integrally with the gear 11 so as to project outwardly on the outer peripheral portion of the body portion 11b of the gear 11. Further, the hook 11d engages with the side surface of the bearing 12, and the gear 1 with respect to the bearing 12
Has a retaining function of 1. The front surface of the hook 11d has a tapered shape. The outer diameter of the tapered tip portion of the hook 11d is smaller than the inner diameter of the body insertion hole 12a of the bearing 12.
Further, the second groove portion 11e is provided to allow the portion including the hook 11d of the body portion 11b to be flexibly deformed toward the inner peripheral portion side of the body portion 11b.

Here, in the second embodiment, unlike the first embodiment, the roller shaft insertion hole 10c is formed as a through hole. The rib 11f is provided integrally with the gear 11 at the tip of the body 11b in the roller shaft insertion hole 11c. The rib 11f has a function of preventing the gear 11 from rotating with respect to the roller shaft 13 by engaging with the first groove portion 13a of the tip end portion of the roller shaft 13. Although not shown, the inner peripheral end surface of the roller shaft insertion hole 11c of the gear 11 is also tapered to facilitate insertion of the roller shaft 13.

The bearing 12 has a body insertion hole 12
a and a hook-shaped protrusion 12b. The body insertion hole 12a is provided to rotatably support the body 11b of the gear 11. Also, the hook-shaped protrusion 1
2b has a hook shape and the bearing 12
Is provided to fix the frame to the frame chassis 14. The bearing 12 is fixed to the frame chassis 14 by engaging the hook-shaped protrusion 12b with an opening (not shown) formed in the frame chassis 14.

As shown in FIG. 4, the bearing 15 is fixed to the frame chassis 14 and has a recess 15a for rotatably supporting the roller shaft 13.
Have. The bottom surface of the recess 15a prevents one end of the roller shaft 13 from coming off in the axial direction.

In the gear mounting structure of the second embodiment, as described above, the pair of hooks 11d having the function of preventing the gear 11 from coming off from the bearing 12 is provided on the outer peripheral portion of the body portion 11b of the gear 11, so that the first Similar to the embodiment, after the body 11b of the gear 11 is fitted into the body insertion hole 12a of the bearing 12, the hook 11d can prevent the gear 11 from coming off the bearing 12. In particular, after inserting the roller shaft 13 into the roller shaft insertion hole 11c of the gear 11, the hook 1
Since the outer peripheral surface of the roller shaft 13 prevents 1d from bending toward the inner peripheral side of the body portion 11b of the gear 11, the gear 11
It is possible to reliably prevent the gear 11 from coming off the bearing 12 even when an axial stress is applied to the gear 12.
As a result, it is possible to reliably prevent the gear 11 from slipping off the roller shaft 13 even when stress is applied to the gear 11 in the axial direction.

Further, in the gear mounting structure according to the second embodiment, as described above, the hook 11d and the rib 11 are provided.
By forming f integrally with the gear 11, the hook 11d and the rib 11f are formed in the gear 1 as in the first embodiment.
The number of parts and the number of assembling steps can be reduced as compared with the case of forming the parts different from 1.

Next, a method of assembling the gear mounting structure in the second embodiment will be described with reference to FIGS.

First, from the state shown in FIG. 5, the body portion 11b of the gear 11 is inserted into the body portion insertion hole 12a of the bearing 12. In this case, since the outer diameter of the tapered tip of the hook 11d is smaller than the inner diameter of the body insertion hole 12a of the bearing 12, the body 11b of the gear 11 is inserted into the body 12 of the bearing 12. When it is inserted into the hole 12a, the tapered portion of the hook 11d is pressed by the inner peripheral side end of the barrel insertion hole 12a of the bearing 12. As a result, the hook 11d is bent and deformed toward the roller shaft insertion hole 11c side, so that the body 11b of the gear 11 is deformed.
Can be easily inserted into the body insertion hole 12a of the bearing 12. Then, with the gear 11 completely inserted in the bearing 12, the body portion insertion hole 12 of the bearing 12
Since the stress applied to the hook 11d from the inner peripheral portion of a disappears, the hook 11d recovers to the shape before the flexural deformation as shown in FIG. As a result, the hook 11d
Engage with the side surface of the bearing 12, so that the gear 11 is axially fixed to the bearing 12.

After that, the roller shaft 13 is inserted into the roller shaft insertion hole 11c of the gear 11, and at the same time, the first groove portion 13a provided at the tip of the roller shaft 13 is inserted.
And the rib 11f provided in the roller shaft insertion hole 11c of the gear 11 are engaged with each other. As a result, the gear 11
Are fixed so as not to rotate with respect to the roller shaft 13.

It should be noted that the embodiments disclosed this time are exemplifications in all respects and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and includes meaning equivalent to the scope of claims for patent and all modifications within the scope.

For example, in the above embodiment, the gear mounting structure in the paper discharge roller portion of the printer has been described as an example, but the present invention is not limited to this, and the gear is fixed to the shaft and the gear is a bearing. It is widely applicable to a device having a structure rotatably supported by.

Further, in the above embodiment, the hooks that engage with the bearing are formed in a tapered shape, but the present invention is not limited to this, and may be formed in any other shape as long as it can engage with the bearing. Good.

[0047]

As described above, according to the present invention, there is provided a gear mounting structure capable of reliably preventing the gear from slipping off from the shaft even when an axial stress is applied to the gear or the shaft. Can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a gear mounting structure according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the gear mounting structure according to the first embodiment shown in FIG.

FIG. 3 is a front view of the gear portion of the gear mounting structure according to the first embodiment shown in FIG. 1, as viewed from the roller shaft insertion direction.

FIG. 4 is a sectional view showing a gear mounting structure according to a second embodiment of the present invention.

5 is an exploded perspective view of the gear mounting structure according to the second exemplary embodiment shown in FIG. 4. FIG.

FIG. 6 is a front view of the gear portion of the gear mounting structure according to the second embodiment shown in FIG. 4, as viewed from the opposite side to the roller shaft insertion side.

[Explanation of symbols]

1, 11 gears 1a, 11a Gear part 1b, 11b body 1c, 11c Roller shaft insertion hole 1d, 11d hook 1e, 11e Second groove part 1f, 11f rib 2,12 bearings 2a, 12a Body insertion hole 3, 13 Roller shaft 3a, 13a 1st groove part

Claims (6)

[Claims] 1. A bearing having a gear portion, a body portion, and a shaft insertion hole, a bearing portion insertion hole into which the body portion of the gear is inserted, the bearing rotatably supporting the gear, and the bearing. In a gear mounting structure of a printer including a frame chassis for mounting a roller shaft and a roller shaft inserted into a shaft insertion hole of the gear, a first groove portion provided at a tip end portion of the roller shaft, and a shaft insertion of the gear. A rib that is provided integrally with the gear in the hole and that engages with the first groove portion of the shaft and that has a function of preventing the gear from rotating with respect to the shaft, and protrudes outwardly on the outer peripheral portion of the body portion of the gear. To be provided integrally with the gear so as to engage with the side surface of the bearing and have a function of preventing the gear from coming off the bearing. A pair of hooks having tapered surfaces, and a portion provided on the body portion of the gear for flexibly deforming a portion of the body portion of the gear where the hook is provided to the inner peripheral side of the body portion of the gear. A gear mounting structure including a second groove portion. 2. A gear having a gear portion, a body portion, and a shaft insertion hole, a body portion insertion hole into which the body portion of the gear is inserted, and a bearing rotatably supporting the gear, and the gear. In a gear mounting structure including a shaft inserted into the shaft insertion hole of the first gear, a first groove portion provided in a tip end portion of the shaft, and a first groove portion provided in the shaft insertion hole of the gear and engaged with the first groove portion of the shaft. And a rib having a function of preventing rotation of the gear with respect to the shaft, and a rib provided on an outer peripheral portion of the body of the gear, engaging with a side surface of the bearing, and having a function of preventing the gear from coming off from the bearing. With a pair of hooks,
Gear mounting structure. 3. The gear mounting structure according to claim 2, wherein the rib is formed integrally with the gear. 4. The gear mounting structure according to claim 2, wherein the hook is formed integrally with the gear. 5. A second groove portion provided on the body portion of the gear, the second groove portion being capable of being flexibly deformed toward an inner peripheral side of the body portion of the gear, the portion being provided with the hook. The gear mounting structure according to any one of claims 2 to 4, further comprising: 6. The gear mounting structure according to claim 2, wherein a front surface of the hook has a tapered shape.