JP2875643B2 - Power transmission device - Google Patents

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 for transmitting a rotational force. More particularly, the present invention relates to a power transmission device having a clutch mechanism in which a driving side and a driven side are connected during rotation, and the driving side and the driven side are disconnected during non-rotation.

[0002]

2. Description of the Related Art Conventionally, in a device for transmitting a driving force by using gears, the gears are connected as shown in FIG. In the gear train of FIG. 5, a large gear 13 meshes with a small gear 12 fixed to a shaft of a motor 11 which is a driving force generating source, and a small gear 14a coaxial with the large gear 13 meshes with a large gear 14.
The small gear 15a, which is coaxial with the large gear 14, meshes with the large gear 15, and the rotational force is transmitted to the large gear 15, which branches and rotates the terminal gears 16, 17 meshing with the large gear 15, respectively.

The small gear 12 meshes with a large gear 18, and a small gear 19a coaxial with the large gear 18 meshes with a large gear 19, and rotates a terminal gear (not shown) via the large gear 19. Such a conventional example is a power transmission device used in office machines, in which a plurality of terminal gears are rotated by the driving force of one motor 11. A gear 17 at the end of the gear train is fixed coaxially with a rubber roller 20 for conveying the sheet 21 as shown in FIG. 6, and by rotating the gear 17 at the end, a sheet guide surface (not shown) and the sheet 21 are rotated. The rubber roller 20 which is in contact with and rotates through the roller rotates the sheet 21. The other terminal gear 16 is fixed coaxially with other rollers similarly to the terminal gear 17 (not shown).

However, in the above-described conventional example, the motor 11 stops due to a conveyance failure of the sheet 21 or other factors,
If a state occurs in which it is necessary to take out the sheet 21 sandwiched between the roller 20 and a sheet guide (not shown), a problem occurs. 6, the sheet 21 is pressed between a sheet guide surface (not shown) and the roller 20, and when the gear 17 rotates, the friction force between the sheet 21 and the rubber roller 20 is large. The paper is conveyed in the direction of the arrow while sliding. However, if the sheet 21 is to be pulled out while the roller 20 is stationary, the frictional force between the sheet 21 and the roller 20 becomes a resistance. The force for pulling out the sheet 21 is the gear 17
The gear 17 is a gear train (gears 12, 13, 14a, 14, 15a, 15,
16, 18, 19a, and 19) are linked to each other, and when the frictional force between the roller 20 and the sheet 21 is large, the sheet 2
In order to pull out 1, a force for rotating all these gears is required. The force required to rotate all these gears depends on the load of a roller or the like (not shown) connected to the terminal gear 16 similar to the gear 17, the holding torque or detent torque of the motor 11, and the inertia of the gear train. The force is greater than the sum of the loads.

Therefore, in order to avoid such a state, the pressure contact force between the roller 20 and the sheet 21 is set to be weak, or a mechanism for reducing the pressure contact force between the roller 20 and the sheet 21 is provided or connected. A mechanism for releasing a connection by using an oscillating gear device that supports a shaft that supports a spring clutch, an electromagnetic clutch, and a gear at an arm end somewhere in a gear train and rotates the arm to disengage teeth. And other measures are taken.

A first embodiment of a process cartridge driving device in an image forming apparatus previously filed by the present applicant is an example in which the connected gears are released by using a spring clutch in conjunction with opening of a cover. .

[0007]

However, in the above-mentioned conventional example, the spring clutch, the electromagnetic clutch, the oscillating gear device, the mechanism for reducing the pressure contact force, and the like are all complicated in structure, resulting in space restrictions and cost. Invite up. Also, in terms of workability, the connection must be released by some operation of the user, and the function may not be performed depending on the operation method. The electromagnetic clutch can interlock the stop of the machine and the release of the connection in sequence, but the power consumption increases.

[0008] In the above measures, there is a possibility that it is necessary to carry out at a plurality of locations on the machine main body. In that case, space restrictions, cost increase, and power consumption increase on the machine configuration are serious drawbacks. In addition, measures to set the frictional force to such an extent that the sheet can be pulled out as it is are difficult to sufficiently apply the sheet conveying force, and the reliability of the sheet conveying function of the machine may be impaired.

[0009]

According to the present invention, in order to eliminate the disadvantages of the prior art, for example, in a gear pair which generates an axial force accompanying the transmission of a driving force, the gear pair is generated in the axial direction. By moving one of the gears in the axial direction using the reaction force, the one gear moves and meshes with the downstream gear only when the drive is transmitted from the drive source upstream side, and the drive is transmitted, When the driving force is not transmitted, the one gear is returned to the original position by the spring again and the connection is released, so that it has a simple configuration, and in particular, does not use separate electric energy or the like, This allows the connection of the drive to be released.

According to a first aspect of the present invention, a driving-side helical gear and a driven-side helical gear are arranged coaxially or in parallel with each other in the axial direction, and the driving-side helical gear is disposed. The clutch has a helical gear for a clutch that is always movable in the axial direction and engages with and disengages from the helical gear on the driven side.The helical gear for the clutch is connected to the helical gear on the driven side. A power transmission device characterized in that a spring is provided so as to urge the helical gear for clutch in the axial direction away from the gear and to provide rotational resistance to the helical gear for clutch.

According to the second aspect of the present invention, the lotus on the driving side is provided.
The helical gear and the driven helical gear are coaxially arranged, and
Always meshes with the driven gear, meshes with the driven gear
The helical gear for the clutch that can
The same pitch and the same number of teeth as the helical gears on the drive side and the driven side
And on the coaxial, the said helical internal gear on the coaxial,
The driven side is between the helical gear and the member that rotates coaxially and integrally.
A power transmission device comprising a coil spring.
It is.

[0012]

FIG. 1 shows a first embodiment of the present invention. A spur gear 3, a helical gear 1 integrated with the spur gear 3,
A helical gear 2 which is coaxial with 1 and a spur gear 4 which is also coaxial with the gears 3 and 1 are rotatably supported on a fixed shaft 9 so as not to move in the axial direction. I have. The teeth of the helical gears 1 and 2 are twisted in the same direction, and have the same pitch and the same number of teeth. A helical internal gear 5 having teeth of the same pitch and the same number of teeth is movably fitted to the helical gear 1 along the tooth trace. The left end of the helical internal gear 5 is detachable from the right end of the helical gear 2 and serves as a clutch gear. A collar 5a is provided on the outer periphery of the helical internal gear 5,
At the boundary between the spur gear 4 and the helical gear 2, a cylindrical portion 2a having the same diameter as the outer diameter of the helical internal gear 5 is provided. The coil spring 6 is disposed between the collar 5a and the spur gear 4, and the helical gear 2 passes through the coil spring 6. Both ends of the coil spring 6 are pressed against the helical internal gear 5 and the spur gear 4 respectively. The helical internal gear 5 is pushed by the spring 6 toward the spur gear 3 when stationary, and the helical internal gear 5 and the helical gear 2 are separated in the axial direction.

The spur gear 7 is a gear that meshes with the spur gear 3 and is further connected to the upstream side for transmitting the driving force. Spur gear 8
Meshes with the spur gear 4, and the spur gear 8 is a gear coaxial with a paper feed roller (not shown).

When the motor serving as the driving source starts rotating, the driving force is transmitted by the connected gear, and the spur gear 7 starts rotating. As shown in FIG. 2, the helical internal gear 5 is shifted toward the helical gear 1 by the spring force of the coil spring 6, and the helical internal gear 5 for the clutch is connected to the helical gear 2. Absent.
The rotation of the spur gear 7 causes the spur gear 3 and the helical gear 1 to start rotating in the direction indicated by the arrow. Then, the helical internal gear 5 meshed with the helical gear 1 receives rotational resistance due to frictional force between the coil spring 6 and the collar 5a or between the coil spring 6 and the spur gear 4. In addition to the rotational power based on the rotational resistance, the helical gear 1 receives a reaction force in the axial direction in the direction of the arrow in FIG. Accordingly, the helical internal gear 5 moves against the spring force of the coil spring 6 in the direction of the arrow while rotating, while rotating.
At this time, both ends of the coil spring 6 are pressed against the spur gear 4 and the collar 5a of the helical internal gear 5, respectively. Further, since the rotating direction of the collar 5a is the direction of contraction of the inner diameter of the coil spring 6, the inner diameter of the collar 5a and the inner diameter of the coil spring 6 are more closely contacted. Twisted by force, the rotational force is stored. The compression is performed by the axial movement of the helical internal gear 5 in the direction of the arrow. When the helical internal gear 5 gradually moves in the direction of the arrow, the helical internal gear 5 reaches a position where the helical gear 2 on the driven side engages, and the helical gear 2 on the driven side, a spur gear 4 starts rotating together with the drive side spur gear 3 and the helical gear 1. The helical internal gear 5 ultimately balances the axial force received from the helical gear 1 with the axially opposed force received from the helical gear 2 and the axially opposed force received from the coil spring 6. Move to the point where they meet (FIG. 3). At this time, the driving force transmitted from the spur gear 7 in FIG. 1 is transmitted from the spur gear 3 to the spur gear 8, and rotates a paper feed roller (not shown) at a constant speed.

Next, when the driving force transmitted from the spur gear 7 disappears, the helical internal gear 5 is pushed back to the original position by the spring force of the coil spring 6 that has been twisted and compressed.
Since the force in the torsion direction of the coil spring 6 acts in a direction to release the meshing of the teeth of the helical internal gear 5 and the helical gear 2,
The transmission of the driving force helps to cause the helical gear 2 and the helical internal gear 5 to be separated from each other in a state in which the tooth surfaces are engaged in the pressed state, so that the mutual sliding motion can be freely generated. In particular, in the case of a molded gear, slight deformation of the teeth can cause the teeth to be locked and locked. The coil spring 6 acts in the direction to release the locked state and pushes the clutch helical internal gear 5 back to the drive side helical gear 1 side.
The coupling between the helical internal gear 5 and the helical gear 2 for the clutch is released. Therefore, as shown in FIG. 2, the driving force is not transmitted from the driven side connected to the roller to the driving side connected to the motor via the gear train.

By the above-described series of operations, when the motor as the drive source starts to rotate, after a slight time lag, the drive force starts to be transmitted, and the drive force input from the spur gear 7 reaches the spur gear 8, A paper feed roller (not shown) coaxial with the spur gear 8 is rotated. When the motor stops rotating, the connection is released again, and the spur gear 4 and the helical gear 2 rotate reversely when the sheet pressed against the roller and the sheet guide is pulled out. At this time, a rotational resistance is generated due to a frictional force between the coil spring 6 and the outer diameter of the spur gear 4 or the helical internal gear 5 for the clutch, but the rotation direction is the direction in which the inner diameter of the coil spring 6 increases.
Its rolling resistance is slight. This solves the conventional problem that the load for rotating all the gears is applied to the sheet pulling force.

[0017]

FIG. 4 shows a modification of the first embodiment. A spur gear 3 meshing with a spur gear 7 connected to a drive source (not shown) is integral with the helical gear 1 and is rotatably supported. A clutch helical gear 5 'meshing with the helical gear 1 is axially moved and rotatably supported by a fixed support shaft 9'. Helical gear 5 'for clutch
The tooth width is larger than that of the helical gear 1 and is always engaged in the axial movement range of the helical gear 5 '. The support shaft 9 'is provided with a flange 10 integrally therewith, and the disk-like friction plate 22 slides against the end surface of the helical gear 5' so as to slide.
Are fitted so as to be movable in the axial direction. Collar 10 and friction plate 2
Both ends of the coil spring 6 contracted between the two are fixed to the collar 10 and the friction plate 22, respectively. In the position shown in the figure, the helical gear 8 'and the helical gear 5' which are axially separated from each other are in a meshing position by the axial movement of the helical gear 5 'in the direction of arrow B. The helical gear 8 'is coaxial with the roller 20.

The driving force transmitted from the driving source (not shown) to the spur gear 7 is transmitted to the integral helical gear 1 coaxially with the spur gear 3 via the spur gear 3, and meshes with the helical gear 1. It is transmitted to the helical gear 5 '. The helical gear 5 'receives a load by the friction plate 22 pressed by the coil spring 6, and receives a force in the direction of arrow A in the figure. Accordingly, the helical gear 5 'for the clutch advances in the direction of arrow B while rotating, and twists and compresses the coil spring 6. When the helical gear 5 'moves in the direction of arrow B in the figure, it reaches the position of the helical gear 8' which rotates together with the roller 20, and the helical gear 8 '
The driving force is transmitted to the helical gear 8 '.

When the motor as the drive source stops rotating, it has a sequence of rotating a fixed amount in the opposite direction. Therefore, at this time, the helical gears 5 'and 8' are released from the locked state of engagement, and return to the original position by the spring force of the coil spring 6. Alternatively, the helical gear 1 returns the clutch helical gear 5 'to its original position depending on the amount of reverse rotation.

By a series of operations described above, when the driving source is started, the roller 20 is driven and starts rotating after a slight time lag, and after the driving source completes the stop sequence, the gears are disconnected. . As a result, the roller 20 rotates while the driving is stopped and does not rotate other gears, so that the force required to pull out the sheet 21 pressed between the roller 20 and the sheet guide is reduced by the roller 20. The sheet 21 can be easily pulled out because only the force for rotating the sheet 21 is sufficient.

[0021]

According to the power transmission device of the present invention, the driving force is connected in conjunction with the turning on / off of the driving force generation source with a simple configuration without adding a function of operating with separate electric energy. Made it possible to cut. Therefore, when the sheet is jammed, it is heavy that the sheet is pulled out, and as a solution to the problem that the sheet is broken and cannot be removed, there is no problem in the operability because the sheet is simply pulled out without any operation, and the cost is low. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a plan view for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a plan view for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a plan view showing a second embodiment of the present invention.

FIG. 5 is a side view showing a gear train for explaining a conventional example.

FIG. 6 is a perspective view illustrating a defect of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 helical gear 2 helical gear 5 helical internal gear 5 'helical gear 6 coil spring 9 shaft

Claims (2)

(57) [Claims] 1. A helical gear on a driving side and a helical gear on a driven side are coaxially or parallelly arranged at an axial distance, and always mesh with the helical gear on the driving side to move in the axial direction. It has a helical gear for the clutch that freely engages and disengages with the helical gear on the driven side, and attaches the helical gear for the clutch in the axial direction away from the helical gear on the driven side. A power transmission device characterized in that a spring is provided to energize and provide rotational resistance to a helical gear for a clutch. 2. A helical gear on the driving side and a helical gear on the driven side.
The car is arranged coaxially and always meshes with the driving gear
A clutch capable of disconnecting engagement with the driven gear.
Helical gear is an internal gear, drive side and driven side
Of the same pitch and the same number of teeth as the helical gear
And the driven side is coaxial with the helical gear.
That a coil spring is placed between the
And a power transmission device.