JPH0211392Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention consists of a feed roller that is rotationally driven in a predetermined direction and conveys the paper, a separation roller that works together with the feed roller to pinch and convey the paper, and a drive that rotates the separation roller in the opposite direction to the paper conveyance direction. A torque limiter for a paper feeding device having a shaft, which drives and connects the drive shaft and the separation roller to apply a constant torque to the separation roller, and when a load greater than the torque is applied to the separation roller, the separation roller is This invention relates to a torque limiter that can rotate independently of a drive shaft. In the above paper feeding device, the tangential force in the direction opposite to the paper conveyance direction on the separation roller is larger than the frictional force between the sheets, the frictional force between the feed roller and the separation roller, and the frictional force between the paper and the separation roller. Set it to be smaller than the friction force of . Thereby, when a sheet of paper passes between the feed roller and the separation roller, the separation roller rotates with the paper and allows the paper to pass. However, when a plurality of sheets overlap and pass between these rollers, the separation roller rotates in a direction opposite to the sheet conveyance direction. Therefore, since the second and subsequent sheets of paper are returned in the opposite direction when viewed from the feed roller, only one sheet of paper is sent to the downstream side of the feed roller and separation roller.
Separate paper feeding is achieved here. As described above, the paper separation performance of this type of paper feeding device is determined by the tangential force on the separation roller in the direction opposite to the paper conveyance direction, and therefore by the set value of the torque applied to the separation roller by the torque limiter. It will be done. At that time, with conventional paper feeding devices,
Since the torque was set to a predetermined value by changing the dimensions of the parts constituting the torque limiter, there was an inconvenience that the set torque value varied due to manufacturing errors of the parts. Since the above-mentioned manufacturing errors are more or less unavoidable when processing parts, the above-mentioned inconvenience has been an unavoidable problem in conventional paper feeding devices. In view of the above points, it is an object of the present invention to provide a torque limiter that can always obtain a constant torque regardless of the dimensional accuracy of the parts. Hereinafter, the present invention will be explained based on drawings showing embodiments thereof. FIG. 1 shows a paper feeding device equipped with a torque limiter according to the present invention. In the figure, sheets 3 stacked on a bottom plate 2 in a cassette 1 are raised to a predetermined upper position together with the bottom plate 2, which is raised by a lifting device (not shown). A pick-up roller 4 is placed in advance above the rising sheets 3 and the bottom plate 2, and this pick-up roller 4 is brought into contact with the uppermost sheet of the sheets 3 at a predetermined timing by a control device (not shown). It also rotates clockwise in the figure. By the rotation of the pick-up roller 4,
The above-mentioned top paper is sent forward along the guide plate G. A feed roller 5 and a separation roller 6 in contact with the feed roller 5 are arranged in front of the pick-up roller 4, and the above-mentioned uppermost paper fed forward is transferred to the feed roller 5 and the separation roller 6 that is in contact with the feed roller 5.
is sent to contact part A of The feed roller 5 is rotated clockwise only during a predetermined timing by a one-way clutch, which will be described later. The separation roller 6 is urged to rotate clockwise under a constant torque by a separation roller shaft 15 as a drive shaft via a torque limiter to be described later. However, the above torque is applied when there is no paper in the roller contact area A or when there is only one sheet of paper, the separation roller 6 rotates with the feed roller 5, and when two or more sheets of paper enter the contact area A. is set to such a size that the separation roller 6 rotates clockwise as indicated by the arrow. Since the separation roller 6 is designed to operate as described above, even if two or more sheets are sent out from the pick-up roller 4 and reach the roller contact area A, the second sheet seen from the feed roller 5 Subsequent sheets of paper are pushed back in the opposite direction to the transport direction as the separation roller 6 rotates clockwise.
Only one separated sheet of paper is fed to the downstream side of the feed roller 5 and separation roller 6. The sheet of paper fed out in this way passes between the upper guide plate 7 and the lower guide plate 8, is corrected for skew etc. by a pair of registration rollers 9, and then moves further forward as shown by arrow B at a predetermined timing. Sent out. As described above, the paper sent out by the pick-up roller 4 is subjected to separation action as necessary by the separation roller 6, which is urged with a predetermined torque under the action of the torque limiter. The torque limiter will be explained in detail. FIG. 2 is a diagram showing the feed roller 5, separation roller 6, etc. along the - line in FIG. 1. In the figure, the feed roller 5 is
It is attached via a one-way clutch 14 to a feed roller shaft 13 having a gear 11 and supported by a bearing 12. The rotation of the feed roller shaft 13, which is rotated by a drive source (not shown) via the gear 11, is transmitted to the feed roller 5 via the one-way clutch 14, and thereby the feed roller 5 rotates at a predetermined timing, as described above. That's right. A separation roller 6 in contact with the feed roller 5 is rotatably mounted on the left end of the separation roller shaft 15 via a bearing 16. The separation shaft 15 is rotatably supported by a bearing 17 at its right end, and supported by a slide bearing 18 at a position inside the separation roller 6 by a predetermined distance. The slide bearing 18 is supported by one arm of the pressure arm 19, as shown in FIG. Pressure arm 19
is rotatable around a support shaft 21, and furthermore, at the tip of the other arm of the arm 19, there is a tension spring 2 fixed to the guide plate G and engaged with a hanging support column 22.
3 is installed. Since the pressure arm 19 is given a counterclockwise rotational habit around the support shaft 21 by the action of the tension spring 23, the slide bearing 18 slides upward in the figure, and therefore the separation roller 6 is pressed against the feed roller 5. In FIG. 2, the separation roller shaft 15
A gear 24 is fixed at a proper position on the right side, and this gear 24 meshes with a gear 26 fixed to one end of a drive shaft 25 that is rotationally driven by a drive source (not shown). With this configuration, the separation roller shaft 15 always rotates in the clockwise direction in FIG. The rotation of the separation roller shaft 15 is
A fixed amount of torque is transmitted to the separation roller 6 by a torque limiter, generally designated by the reference numeral 27. The torque limiter 27 includes a fixing screw member 31 fixed on the periphery of the separation roller shaft 15 by a spring pin 28 and further provided with a screw 29a on the outer periphery extending in the axial direction of the shaft 15, and a screw that engages with the screw 29a. 29b on the inner peripheral surface and can be fixed on the fixing screw member 31 with a set screw 32, and a clutch attached between the small diameter part 33a of the hub 33 and the small diameter part 6a of the separation roller 6. It has a spring 34.
The clutch spring 34 is fixed on the separation roller side and slidable on the hub side. That is, the small diameter portion 33a of the hub 33 is set smaller than the small diameter portion 6a of the separation roller 6. With this configuration, the rotation of the separation roller shaft 15 is transmitted to the separation roller 6 unless slippage occurs between the hub small diameter portion 33a and the clutch spring 34, and in that case, the separation roller 6 is rotated as shown in FIG. Rotates clockwise inside. However, if the load applied to the separation roller 6 by the feed roller 5 exceeds a predetermined value, the spring 3
4 and the hub small diameter portion 33a, so that from then on the separation roller 6 does not follow the rotation of the shaft 15, but exclusively follows the movement of the feed roller 5. In other words, torque limiter 27
This means that a constant torque is transmitted to the separation roller 6, and the torque is generally given by the following equation. T ₎ = Rd/Rf・R ² e(Re−Rf)EI (1−e ⁻² 〓〓 ^N ) … However, Rd: Radius of hub small diameter portion 33a Rf: Free radius of spring 34 + Free height of spring 34 Re: radius of the hub small diameter portion 33a + free height of the spring 34 E: modulus of longitudinal elasticity I: moment of inertia of area μ: coefficient of friction between the spring 34 and the hub small diameter portion 33a N: effective number of turns. As is clear from the above equation, as the value of the effective number of turns N increases, the torque T ₀ to be transmitted also increases, and conversely, as the number of turns N decreases, the torque T ₀ also decreases. Therefore, in Fig. 2, the value of torque T ₀ can be freely adjusted by loosening the setscrew 32 to allow the hub 33 to rotate freely, and by screwing it in to the left in the figure or pulling it out to the right. . As mentioned above, the torque to be applied to the separation roller 6 is such that when there is no paper at the roller contact area A or only one sheet of paper, the separation roller 6 rotates along with the feed roller 5, while the torque applied to the contact area A is When two or more sheets of paper are loaded, the size must be set so that the separation roller 6 is driven to rotate along the shaft 15, but in this embodiment, the hub 3 is
Since the torque value can be freely adjusted by tightening the screw in step 3, the torque limiter 27
When setting the torque in , the hub 33 may be adjusted after the torque limiter 27 is assembled onto the separation roller shaft 15. Therefore, there is no need to finish components such as the hub 33 and spring 34 with particular precision as in the past, and there is no problem even if some errors occur during assembly. Furthermore, even if the set torque deviates from the target value after using the paper feeding device according to this example for a long time,
Since this can be corrected, it is possible to maintain good paper feeding performance for a long time. By the way, the length of one side of the spring 34 is
When using one with a square cross section of 1.14 mm, the results shown in the following table are obtained for the above formula.

[Table] From the table above, when the effective number of turns N is set to about 2 to 3, the torque will fluctuate by 10 to 20%. As mentioned above, since the spring uses □1.14, the desired torque can be obtained by adjusting it by about 1 to 2 mm. The embodiment of the present invention in which a spring clutch is used as a torque limiter has been described above, but even if a spring clutch is used as a torque limiter, if the torque can be adjusted, it will be possible to process parts in the same manner as in the above embodiment. Effects such as ease of assembly and assembly work are obtained.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a paper feeding device showing one embodiment of the present invention, and FIG. 2 is a sectional view taken along the - line in FIG. 1. 3... Paper, 5... Feed roller (feed roller), 6... Separation roller (separation roller), 15... Separation roller shaft (drive shaft), 27... Torque limiter, 34... Clutch spring, 31... ...Fixing screw member, 33...
hub.

Claims (1)

[Scope of Claim for Utility Model Registration] A feed roller that is rotationally driven in a predetermined direction to convey the paper, a separation roller that works together with the feed roller to pinch and convey the paper, and a separation roller that is rotationally driven in the opposite direction to the paper conveyance direction. A torque limiter for a paper feeding device, which is equipped with a drive shaft for separating the paper, and the drive shaft and the separation roller are drivingly connected to apply a constant torque to the separation roller, and a load larger than the torque is applied to the separation roller. Sometimes, in a torque limiter that allows the separation roller to rotate independently of the drive shaft, a clutch spring is installed between the separation roller and the drive shaft, fixed to the separation roller side and slidable from the drive shaft side, and a clutch spring installed on the drive shaft. a fixing screw member that is fixed and has a screw on its outer periphery that extends in the axial direction of the axis of the drive shaft, and a screw that engages with the screw of the fixing screw member, and by tightening or loosening the screw, the axis of the fixing screw member can be moved along the axis of the fixing screw member. a hub that is movable in the axial direction and engages with the sliding side of the clutch spring, and the constant torque can be adjusted by changing the effective number of turns of the clutch spring by moving the hub in the axial direction. A torque limiter featuring: