JPH0133547Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field This invention relates to a friction roller separation type sheet conveying device having a torque limiter.

Prior Art In a copying machine, a facsimile machine, etc., a device for feeding stacked sheets one by one is a device loaded on a movable bottom plate 16 on a paper feed cassette 15, as shown in FIGS. 1 to 3, for example. A pick-up roller 1 that is pressed against the front edge of the upper surface of the paper stack 17 and rotates in the paper feeding direction in response to a paper feeding signal to send out the uppermost paper;
A feed roller 2 that rotates in the paper feeding direction in synchronization with the pick-up roller 1, a reverse roller 3 that pinches the paper path and presses against it and is rotatably supported in forward and reverse directions, and a reverse roller 3 that rotates in the paper feeding direction; Torque limiter T that applies a constant torque in the paper direction
(FIG. 3) A friction roller separation type paper conveyance device is known. The magnitude of the torque applied to the reverse roller 3 by this torque limiter is calculated as the torque in the paper feeding direction applied to the reverse roller 3 due to the frictional force between the feed roller 2 and the reverse roller 3 and the frictional force between these rollers and the paper. If it is set to a value that is smaller than both of these, and larger than the torque in the sheet feeding direction given to the reverse roller 3 due to the frictional force between the sheets that are fed between the rollers 2 and 3, In a state where the paper to be fed has not yet reached the gripping portion of both rollers and both rollers are in direct contact with each other, and in a state where only one sheet of paper is fed between both rollers, the reverse roller 3 is moved by the torque limiter T. If the feed roller rotates in the paper feeding direction against the torque in the opposite paper feeding direction, and two or more sheets of paper are fed between both rollers, the reverse roller 3
The torque from the torque limiter causes the lower paper to be dragged along by frictional force and rotated in the opposite direction to the feed roller, and the paper in contact with the feed roller is conveyed in the paper feed direction by the frictional force with the roller, and the double feed is separated and fed one by one. Paper can. Since this method does not cause slippage between the rollers or between the rollers and the paper, it prevents wear of the rollers, ripples and fuzzing of the paper, and generation of paper dust, and reduces the coefficient of friction due to paper dust adhering to the rollers. This has advantages such as avoiding instability of the separation action due to

The above-mentioned torque limiter includes, for example, a drive hub 6 which is rotatably supported on a driven shaft (reverse roller shaft 24 in this example) and rotationally driven by a drive shaft 23 via a gear 4, as shown in FIG. A coil spring 25 is wound with a certain tightening force across the outer circumferential surface of a driven hub 26 which is adjacent to the driven hub 26 and is fixed to rotate integrally with the driven shaft. 26
In addition, when torque is further transmitted to the driven shaft 24 and a load is applied to the driven shaft 24 in the opposite direction to the torque, the spring 25 is twisted in the direction in which its diameter increases, and the tightening force on the driven hub 26 is loosened. A structure in which the transmission torque is regulated to a certain value or less as a result of slipping is simple in structure, and is often adopted in sheet conveyance devices of the friction roller separation type.

In a friction roller separation type sheet conveyance device, a pick-up roller, a feed roller, and a reverse roller are often installed one each on the center line, but when the conveyance width is wide, a pick-up roller is installed as shown in Figures 2 and 3. Examples are often seen in which two rollers 1, two feed rollers 2, and two reverse rollers 3 are used on each side.

in this case, (a) Equalize the pressure on the two feed rollers.

(b) Equalize the separation torque of the two reverse rollers.

(c) Reverse torque of the required magnitude can be obtained.

It is necessary. The above (a) and (b) are related to each other, and if the pressures are equal, the torques will necessarily be equal.

However, even when two rollers are provided on each side, in conventional devices, only one torque limiter T is normally provided near the center, as shown in FIG. In the example shown here, the drive hub 6 of the torque limiter T meshes a gear provided on the outer periphery of one end of the drive hub 6 with a pressurizing gear 4 fixed to a reverse drive shaft 23 that is rotationally driven by a drive source. driven by. The reverse shaft 24 is pivotally supported near both ends by a pressure lever 5 that is pivotally supported by the reverse drive shaft 23, and the reverse roller 3 is fixed to the outside thereof. A pressure shaft 22 is attached by connecting the other ends of the pressure levers 5 on both sides, and by tensioning a pressure spring 7 between the pressure shaft 22 and the machine frame as shown in FIG. The reverse roller 3 is configured to come into pressure contact with the feed roller 2.

The torque limiter T is provided on the reverse drive shaft 23, as shown in FIG. It is also possible to transmit it to the shaft 24.

Now, the required reverse torque is, for example, 500g.
If the size becomes larger than cm, if only one torque limiter is provided, the load on the torque limiter spring becomes too large.
Excessive friction between the spring and hub causes temperature rise and wear, which shortens the life of the torque limiter.

Also, as shown in FIG. 3, the positions of the pressure gear 4 and the gears provided on the torque limiter drive hub 6 are adjusted to
3 and 24, the center of gravity of the driven hub 26 of the torque limiter is located at a position offset from the center, resulting in a difference in initial pressure between the reverse roller 3 and the feed roller 2 on both sides. Therefore, if the contact part between the driving hub 6 and the driven hub 26 is brought to the center of the shaft, the weight will be balanced, but since the meshing position of the gear will be offset from the center, the gear 4 will be rotated to apply pressure to the reverse roller 3. At this time, a difference occurs in the pressure between the pair of rollers 3 and 4 on both sides. Further, when there is only one torque limiter, the reverse shaft 24 performs a so-called sliding motion due to the influence of the winding direction of the spring, and the pressure of the reverse roller fluctuates.

As a result of the above, a difference occurs in the separation torque between the front and rear reverse rollers and the conveyance force of the feed roller, resulting in problems such as skew, meandering, and waving in the conveyance.

Purpose The purpose of this invention is to provide a sheet conveying device of the conventional friction roller separation type sheet conveying device having one torque limiter, which solves the above-mentioned problems.

Configuration The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 5 is a sectional view taken along a plane including the center lines of the reverse roller shaft 24 and the reverse drive shaft 23 of the sheet conveying device according to the first embodiment of the present invention. In this embodiment, the torque limiters are provided on the reverse drive shaft ₂₃ as in _FIG .
The pieces are arranged symmetrically. Further, the reverse roller 3 is provided integrally with a gear 32 that meshes with a gear 31 provided on a driven hub 30 of the torque limiter. One of the springs 25 and 25' of the two torque limiters T ₁ and T ₂ is left-handed and the other is left-handed.

With the above configuration, the reverse torque required for the two reverse rollers 3 is shared and applied by the two torque limiters T ₁ and T ₂ , so that the springs 25 and 25' of each torque limiter T ₁ and T ₂ are applied separately. The force applied to the torque limiter is half of that when there is only one torque limiter, and the friction between the springs 25, 25' and the hub is reduced, temperature rise due to frictional heat and wear of parts are reduced, and the lifespan is extended. By making the winding directions of the springs 25 and 25' of T ₁ and T ₂ opposite to each other, the influence of the winding direction is canceled out.

In this case as well, the torque limiters T ₁ and T ₂ are not provided on the reverse drive shaft 23, as shown in FIG.
It goes without saying that the reverse roller 3 may be provided on the reverse shaft 24 and the reverse roller 3 may be integrally provided on its driven hub.

In the embodiment shown in Fig. 5, two torque limiters are used.
By providing T ₁ and T ₂ integrally with the reverse rollers on the rear and front sides of the reverse shaft 24, respectively, the configuration is simplified and, as mentioned above, the drawbacks of the conventional device have been considerably improved, but in reality The torque transmitted by each of the two torque limiters is 100% due to variations in the dimensions of parts such as the hub and spring diameter.
The occurrence of a difference on the order of g·cm is unavoidable. If there is a difference in reverse torque between the front side and the back side, this may cause skew when paper is conveyed or fed back.

In the embodiment shown in FIG. 7, in order to improve this point, torque limiters are integrally provided on the front side and the back side of the reverse gear 32 provided at the center of the reverse shaft 24.
Drive hubs T ₁ and T ₂ are formed, and driven hubs 2 are fixedly attached to the reverse shaft 24 adjacent to each of them.
The two torque limiters T ₁ and T ₂ are integrally formed in the center of the reverse shaft 24 by winding springs 25 and 25' with different winding directions across the reverse shaft 6 and 26'. Although the reverse rollers 3 are not shown, they are symmetrically provided at both ends of the reverse shaft 24 as in FIG. 3.

This configuration not only avoids the generation of heat due to friction of the torque limiter member, wear, and the influence of the spring winding direction, but also makes it possible to equalize the pressure between the two sets of reverse rollers and feed rollers. It is also possible to prevent the occurrence of skew, etc. In this case as well, torque limiters T ₁ and T ₂ may be provided on the reverse drive shaft 23 and torque may be transmitted to the reverse shaft 24 via a gear.

In the embodiment shown in Fig. 7, when using overrun torque, it is preferable that the spring 25' on the back side is wound to the right, and the spring 25 on the hand-wound side is preferably wound to the left. It is better to wind it in the opposite direction.

Effects As described above, according to the present invention, by providing two torque limiters, the load on each torque limiter is halved, temperature rise and wear caused by friction of the members are reduced, and the service life is extended. In addition, by reversing the winding direction of the springs of the two torque limiters, the influence of the winding direction is canceled out, and by arranging the members symmetrically, the pressure on the left and right roller pairs becomes equal, which helps prevent skew. Effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a friction roller separation type sheet conveying device having a conventionally known torque limiter, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is a cross-sectional view taken along the - line in FIG. 1. 4 is a sectional view showing another configuration example of the torque limiter in FIG. 3, FIG. 5 is a sectional view corresponding to FIG. 3 of the embodiment of the present invention, and FIG. FIG. 7 is a sectional view showing the vicinity of a torque limiter according to another embodiment of the present invention. 2... Feed roller, 3... Reverse roller, 23... Reverse drive shaft, 24... Reverse roller shaft, 25, 25'... Spring, T ₁ , T ₂
...Torque limit.

Claims (1)

[Claims for Utility Model Registration] (1) A feed roller that rotates in the paper feeding direction, a reverse roller that pinches and presses against the sheet path and is pivotally supported for forward and reverse rotation, and a reverse roller that rotates in the paper feeding direction. In a sheet conveying device having a spring torque limiter that applies a constant torque in a direction, the spring torque limiter is provided with a pair of springs whose winding directions are left-handed and right-handed. A sheet conveying device characterized by: (2) The above-mentioned springs with left-handed and right-handed winding directions are fitted into both sides of an integrally formed body provided near the center of the above-mentioned reverse roller shaft or its drive shaft, and near both ends of the shaft. The sheet conveying device according to claim 1, wherein each of the sheet conveying devices is provided with one reverse roller.