JPH0650406A - Power transmission device - Google Patents

Abstract

PURPOSE:To provide a power transmission device wherein a pushing force in the direction of tooth depth is reduced when a tooth of a first gear and a first tooth in the downstream of the rotational direction at a tooth lack part of a second gear come in contact with each other. CONSTITUTION:A power transmission device is provided with a driven gear 9 having a plurality of teeth 10 meshed with teeth 8 of a drive gear 6 and a toothless tooth lack part 11 adjacent to the drive gear 6 having a plurality of teeth 8. Portions of a first tooth 10a and a second tooth 10b positioned downstream of the tooth lack part 11 of the driven gear 9 in the rotational direction E are made elastically deformable in the direction of tooth depth, a first inclined surface 16 notched in the direction from the dedendum side of the side face in the upstream of the first tooth 10a to the tooth tip side of the side face in the downstream is formed, and a second inclined surface 17 notched in the direction from the tooth tip side of the side face in the upstream of the second tooth 10b to the dedendum side of the side face in the downstream is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device used in a paper feed roller drive system for office machines such as copying machines, facsimiles, printers and electronic files.

[0002]

2. Description of the Related Art FIGS. 8 and 9 show a conventional example. In the figure, 100 is a drive gear as a first gear, and the drive gear 100 rotates about a shaft 101 in the clockwise direction in the figure. The gear 100 has a plurality of teeth 104.

Further, 102 is a driven gear as a second gear, and the driven gear 102 is fixed to a shaft 103. The driven gear 102 has a plurality of teeth 105 and a toothless portion 106.

A cam 107 is formed integrally with the driven gear 102. The cam 107 has a locking portion 108. Pins 109 and 110 are provided on the cam 107 and the apparatus main body side, and tension springs 111 are hooked on the pins 109 and 110.

On the other hand, the apparatus main body side has a solenoid 112 and a movable piece 113.

In the above structure, the drive gear 100 always rotates clockwise. Further, the driven gear 102 is given a moment to rotate in the counterclockwise direction by the elastic force of the tension spring 111, but the solenoid 112 moves to the O position.
Since the claw 114 of the movable piece 113 is locked to the locking portion 108 in the FF state, the driven gear 102 is stopped at the position shown in FIG.

That is, the toothless portion 106 and the drive gear 100 correspond to each other and the drive gear 100 and the driven gear 102 are out of mesh with each other, and the rotation of the drive gear 100 is driven by the driven gear 10.
2 is not transmitted.

On the other hand, when a voltage is applied to the solenoid 112 and it is excited, the movable piece 113 moves to the position indicated by the chain double-dashed line, and the claw 114 is disengaged from the locking portion 108.

Then, the driven gear 102 has a tension spring 111.
The elastic force causes the pre-rotation in the counterclockwise direction, the teeth 105 mesh with the teeth 104 as shown in FIG. 9, and the rotation of the drive gear 100 is transmitted to rotate the driven gear 102.

[0010]

However, in the above-mentioned conventional example, depending on the timing of the preliminary rotation of the driven gear 102,
The movement of the teeth 104 of the drive gear 100 and the downstream first teeth 105a of the toothless portion 106 of the driven gear 102 may be synchronized. As a result, the top surface 115 of the tooth 104 and the top surface 116 of the tooth 105 come into contact with each other and push in the direction of the tooth depth, and the resistance causes damage to the teeth 104 and 105a or the drive gear 10.
There was a problem that the power transmission function was impaired because 0 stopped.

The present invention is to solve the above-mentioned problems, and a pressing force in the tooth depth direction when the teeth of the first gear and the first teeth on the downstream side in the rotational direction of the toothless portion of the second gear come into contact with each other. It is an object of the present invention to provide a power transmission device with reduced power consumption.

[0012]

To achieve the above object, the first means of the present invention is to provide a plurality of teeth which mesh with the teeth of the first gear in the vicinity of the first gear having a plurality of teeth and no teeth. In a power transmission device provided with a second gear having a toothless portion,
The first tooth and the second tooth portion located on the downstream side in the rotation direction of the toothless portion of the second gear are configured to be elastically deformable in the tooth depth direction, and the first tooth and the second tooth portion are downstream from the root side of the upstream side surface. The first inclined surface that is cut out toward the tip side of the side surface of the second side, and is cut out from the tip side of the upstream side surface of the second tooth toward the root side of the downstream side surface. An inclined surface was formed.

Further, the second means is a power transmission in which a second gear having a plurality of teeth meshing with the teeth of the first gear and a toothless toothless portion is provided in the vicinity of the first gear having a plurality of teeth. In the device, the second gear is configured to be elastically deformable in the tooth cap direction from the first tooth to the third tooth located on the downstream side in the rotational direction of the toothless portion, and is upstream from the first tooth to the n-th tooth. Has a first inclined surface that is cut away from the root side of the side surface toward the tip side of the downstream side surface, and n + one tooth has teeth from the tip side of the upstream side surface to the tooth side of the downstream side. It has a second inclined surface cut out toward the original side.

The material of the second gear of the first and second means is plastic.

Further, the end surfaces of the first and second teeth of the first means are asymmetric.

Furthermore, the end face shapes of the nth tooth and the (n + 1) th tooth of the second means are asymmetric.

[0017]

When the movement of the teeth is synchronized, the teeth of the first gear come into contact with the first inclined surface of the second gear, the rotation of the second gear is slightly delayed, and the pushing of the teeth is prevented. When the tops of the teeth of the first gear and the tops of the teeth of the second gear come into contact with each other, the teeth of the second gear are elastically deformed in the tooth depth direction to reduce the pressing resistance.

Further, the contacted teeth move simultaneously due to contact resistance, and the teeth of the first gear and the second inclined surface of the second tooth of the second gear come into contact with each other as the teeth rotate. Although the first and second tooth portions try to restore, the second gear rotates a little faster upstream due to the presence of the second inclined surface.

[0019]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a paper feeding mechanism for a copying machine, a printer, a facsimile, an electronic file, and the like. Transfer papers 2 are stacked in a paper feed cassette 1 mounted on a device body (not shown). The paper feed cassette 1 has a separation claw 3. On the device body side and above the paper feed cassette 1, there is a half-moon-shaped paper feed roller 4 attached to a shaft 5. The paper feed roller 4 intermittently rotates in the direction of arrow A, and the separation claws 3 separate the sheets one by one. Separate and feed in the direction of arrow B. (First Embodiment) FIG. 2 shows a first embodiment of a power transmission device used for rotating the paper feed roller 4. Reference numeral 6 denotes a drive gear serving as a first gear provided on the device body side and fixed to the shaft 7. The drive gear 6 has a plurality of teeth 8 over the entire circumference and is constantly rotated in the direction of arrow D by a motor or the like not shown.

Below the drive gear 6, a driven gear 9 as a second gear attached to the shaft 5 is provided. The driven gear 9 is made of engineering plastic typified by nylon, polyacetal or the like, and has a lower rigidity than a metal gear. In the illustrated embodiment, the pitch circle diameter of the driven gear 9 is set larger than the pitch circle diameter of the drive gear 6.

The driven gear 9 has a plurality of teeth 10 and a toothless portion 11 having no teeth. Further, an arc-shaped slit 14 is provided on the downstream side of the toothless portion 11 of the driven gear 9 in the rotation direction E, and constitutes a flexible portion 12. The flexible portion 12 is elastically deformable in the radial direction with the fixed end 13 side serving as a fulcrum.

Then, the first inclined surface 16 is formed by cutting out from the root side of the upstream side surface of the first tooth 10a near the toothless portion 11 toward the tip side of the downstream side surface, The second inclined surface 18 is formed by cutting out from the tip side of the upstream side surface of the tooth 10b toward the root side of the downstream side surface.

On the other hand, a cam 19 is integrally provided on the side surface of the driven gear 9. A pin 20 is provided on the side surface of the cam 19, and a pin 21 is also provided on the device body side. A tension spring 22 is attached to the pins 20 and 21. A locking portion 23 is provided on the outer circumference of the cam 19.

Further, below the driven gear 9, the holder 2 is provided.
There is provided a solenoid 25 held by 4. A movable piece 26 that operates like a seesaw is attached to the holder 24, and a claw 27 is formed on one end side of the movable piece 26.

A pin 28 is provided on the outer surface of the holder 24, and a tension spring 29 is hooked on the other end 30 of the movable piece 26 and the pin 28.

In the above structure, the drive gear 6 is constantly rotating in the direction of arrow D. Further, the driven gear 9 is the tension spring 2
The elastic force of 2 gives a moment to rotate in the direction of arrow E. On the other hand, since the solenoid 25 is in the OFF state, the claw 27 of the movable piece 26 that is pulled by the tension spring 29 is locked to the locking portion 23 as shown by the solid line. Therefore, regardless of the existence of the above moment, the driven gear 9 is
Has stopped at the position.

As a result, the toothless portion 11 and the drive gear 6 correspond to each other and the drive gear 6 and the driven gear 9 are out of mesh with each other, and the rotation of the drive gear 6 is not transmitted to the driven gear 9.

On the other hand, when a voltage is applied to the solenoid 25 to excite it, the movable piece 26 is moved to the position indicated by the chain double-dashed line by the generated attractive force, and the pawl 27 is disengaged from the locking portion 23.

Then, the driven gear 9 is preliminarily rotated in the direction of arrow E by the elastic force of the tension spring 22, the first tooth 10a is brought into mesh with the tooth 8, and thereafter the driving gear 6 is meshed with the gear.
Is transmitted to rotate the driven gear 9. At this time, the solenoid 25 is turned off.

When the most downstream portion of the tooth 10 comes out of the tooth 8, the state shown in FIG. 2 is established and the power transmission to the driven gear 9 is stopped.

When the movements of the teeth 10 and 8 are synchronized, the teeth 10 of the drive gear come into contact with the first inclined surface 16 of the driven gear 9 and the rotation of the driven gear 9 is slightly delayed.
Pushing between a and 8 is prevented. Even if they are pressed against each other, the bending portion 12 of the driven gear 9 is elastically deformed in the direction of the tooth engagement to reduce the pressing resistance.

Subsequently, the teeth 10a, 8 contacting each other move due to contact resistance, and the tooth 8 of the drive gear 6 and the second inclined surface 17 of the second tooth 10b of the driven gear 9 come into contact with the rotation. Then,
Although the flexible portion 12 tries to restore to the outer peripheral side, since the second inclined surface 17 and the tooth 8 are in contact with each other, the driven gear 9 is slightly faster than the rotation of the drive gear 6 upstream due to the reaction force of the restoring force. Rotate straightening to. As a result, the first teeth 10a and the first teeth 10b accurately enter between the teeth 8.

Therefore, the teeth 10, 8 are not damaged and the drive gear 6 is not stopped, and a stable power transmission function can be secured. (Second Embodiment) In FIG. 5, a first inclined surface 16 is formed on the first tooth 10a and the second tooth 10b, and the third tooth 10c is formed.
The second inclined surface 17 is formed on the. Other configurations are similar to those of the first embodiment.

In this embodiment, the first tooth 10a and the second tooth 10b are used.
Even when the tooth 8 rides on the tooth 8, the same action as described above occurs due to the second inclined surface 17 of the third tooth 10c, and the same effect as that of the first embodiment can be obtained.

The first inclined surface may be formed up to the third tooth and the fourth tooth, and the second inclined surface may be formed on the teeth thereafter. (Third Embodiment) Regarding the shape of the inclined surface, in the worst case, when the first tooth 10a having a notch on the upstream side and the second tooth 10b having a notch on the downstream side have symmetrical shapes, FIG. It is also conceivable that the edges of the second teeth 10b and the teeth 8 collide with each other as shown in (), and the corrective rotation action of the first embodiment does not function. Therefore, as shown in FIG. 6B, the first tooth 10a and the second tooth 10b have an asymmetrical shape (difference in inclination angle).
Therefore, even if the edges of the first tooth 10a and the tooth 10 come into contact with each other, the inclined surface 17 of the second tooth 10b and the edge of the tooth 8 come into contact with each other, so that the corrective rotation action can be performed. (Fourth Embodiment) In the fourth embodiment, a toothless portion 11, a slit 14 and a flexible portion 12 are formed at two locations in opposite directions by 180 degrees in the fourth embodiment. The cam 19 also has two locking portions 23. Further, a spindle-shaped biasing cam 40 having two protrusions 41 is attached to the shaft 5. A leaf spring 42 is in contact with the outer peripheral surface of the biasing cam 40. Other configurations are similar to those of the first embodiment.

In the present embodiment, when the solenoid 25 is turned on, the elastic force of the leaf spring 42 preliminarily rotates the driven gear 9, which has the same effect as the first embodiment.

Further, since there are two locking portions 23, the driven gear 9 stops at every rotation of about 180 degrees, and the transmission of power is released at each rotation.

Although not shown in the drawing, intermittent control can be performed every 1/3 rotation and 1/4 rotation by providing the toothless portion, the bending portion, and the locking portion at three locations and four locations.

The first gear of the above embodiment may be a driven gear and the second gear may be a drive gear.

[0040]

As described above, even if the teeth of the first gear and the teeth of the second gear move in synchronism, it is possible to reduce the pressing resistance between the teeth and to correct them in an appropriate meshed state. . Therefore, the power transmission function can be stably maintained without damaging the teeth or stopping the first gear.

[Brief description of drawings]

FIG. 1 is a sectional view of a sheet feeding mechanism of a copying machine to which the present invention is applied.

FIG. 2 is a diagram showing the configuration of a first embodiment of the power transmission device used in FIG.

3A and 3B are partial views showing the operation of FIG.

4A and 4B are partial views showing the operation of FIG.

FIG. 5 is a diagram showing the configuration of a second embodiment of the power transmission system of the invention.

FIG. 6A is a diagram of a first embodiment when the first and second teeth are symmetrical, and FIG. 6B is a diagram of a third embodiment having an asymmetrical shape.

FIG. 7 is a diagram showing the configuration of a fourth embodiment of the power transmission device of the present invention.

FIG. 8 is a diagram showing a configuration of a conventional example, in which a driven gear is stopped.

FIG. 9 is a diagram showing a configuration of a conventional example, in which a driven gear is rotated.

[Explanation of symbols]

 6 Drive Gear (First Gear) 8, 10 Teeth 11 Partial Tooth Part 10a First Teeth 10b Second Teeth 9 Driven Gear (Second Gear) 16 First Sloping Surface 17 Second Sloping Surface

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masao Ando 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A power transmission device, comprising: a second gear having a plurality of teeth meshing with the teeth of the first gear and a toothless portion having no teeth in the vicinity of the first gear having a plurality of teeth. The first tooth and the second tooth portion located on the downstream side in the rotation direction of the toothless portion of the second gear are configured to be elastically deformable in the tooth brushing direction, and from the root side to the downstream side of the upstream side surface of the first tooth. Forming a first inclined surface notched toward the tooth tip side of the side surface of the second tooth, and notched from the tooth tip side of the upstream side surface of the second tooth toward the tooth root side of the downstream side surface A power transmission device having a surface. 2. A power transmission device comprising a second gear having a plurality of teeth that mesh with the teeth of the first gear and a toothless portion having no teeth, in the vicinity of the first gear having a plurality of teeth. The second gear has a configuration in which the first tooth to the third tooth located on the downstream side in the rotation direction of the toothless portion are elastically deformable in the tooth-take direction, and the first tooth to the n-th tooth are on the upstream side surface. It has a first inclined surface that is cut out from the root side toward the tip side of the downstream side surface, and n + one tooth faces from the tip side of the upstream side surface to the root side of the downstream side surface. A power transmission device having a second inclined surface cut out. 3. The power transmission device according to claim 1, wherein the material of the second gear is plastic. 4. The power transmission device according to claim 1, wherein the end surfaces of the first teeth and the second teeth are asymmetric. 5. The power transmission device according to claim 2, wherein the end surfaces of the nth tooth and the (n + 1) th tooth are asymmetric.