JPH02107838A - Torque limiter for driven roller - Google Patents

Abstract

PURPOSE:To stabilize the torque by providing a pair of poll piece made of the magnetic material and fixed on the outer peripheral surface of a pivot, a parmanent magnet pinched to be fixed between them, the magnetic fluid held between the peripheral parts of each poll piece and the inner surface of a housing, and a bearing for supporting the housing pivitallys. CONSTITUTION:When a housing 8 is rotated in the tortional direction against a pivot 3, the shearing force is applied to the magnetic fluid 10, and the torque is generated in the tortional direction between the pivot 3 and the housing 8. The relative rotation of the pivot 3 with the housing 8 is performed by a pair of slip bearing 7, 7 provided so as to pinch poll pieces 6, 6. Since the mutual friction between the outer peripheral of a pair of the poll piece 6, 6 and the inner peripheral surface of the housing 8 is not generated, the torque generated between the pivot 3 and the housing 8 is stabilized from the first. Since the heat and the friction accompanied with the use of a torque limiter is not generated, the stabilized performance can be obtained for a long period.

Description

[Detailed Description of the Invention] (Industrial Application) The torque limiter for driven rollers according to the present invention is built into copiers, various printers, etc., and is designed to prevent two or more sheets of paper from being sent backwards at once. Use it by incorporating it into an automatic paper feeder.

(Prior Art) The automatic paper feeding devices of copying machines and various printers must feed sheets of paper, which have been cut into sheets and stacked one on top of the other, stored in a cassette, etc., one by one to the rear where the printing section, etc. is located. It won't happen.

However, when taking out thin sheets of paper from a cassette, it is difficult to stably take out one sheet at a time, and it is often necessary to take out two or more sheets at once.

Even in such a case, as shown in Figure 14, a motor is used to separate the sheets taken out in front of the printing section and feed the sheets one by one into the printing section. A separation mechanism is provided which includes a driving roller 1 and a driven roller 2 rotatably supported via a torque applying device.

Of the driving roller 1 and driven roller 2 that constitute this separation mechanism, the driving roller 1 is fixed to a driving shaft 18 of a motor that rotates clockwise in FIG. 14, and rotates in synchronization with this driving @ 18. A torque limiter 19 is provided between the driven roller 2 and the pivot shaft 3, which rotates in the same direction as the drive shaft 18 (clockwise in FIG. 14), and Rubber tubes with covered surfaces are brought into elastic contact with each other.

Therefore, when a strong frictional force acts between the outer peripheral surface of the driving roller 1 and the outer peripheral surface of the driven roller 2, the driven roller 2 is moved in the opposite direction to the driving roller 1 (the 14th However, if there is a slippery surface between both rollers 1.2, this surface will slip, causing the driven roller 2 to rotate in the same direction as the driving roller 1 (the 14th (clockwise in the illustration).

Therefore, if only one sheet of paper is fed between the driving and driven rollers 1.2, both sides of this paper and both rollers 1.
．． Due to the strong frictional force acting between the rollers 1.2 and the rubber cylinder covering the outer peripheral surface of the rollers 1.2, both rollers 1.2 rotate in opposite directions, and the paper sandwiched between the rollers 1.2 is pushed backwards (as shown in Figure 14). As shown in Fig. 14, the driving, driven, and both rollers 1.
When two sheets of paper 4a, 4b are fed in a superimposed state between the two sheets of paper 4a and 4b, the strong frictional force acting between the rubber cylinder covering the outer peripheral surface of the drive roller 1 and the surface of one of the sheets of paper 4a causes this Only the paper 4a is sent backward.

In this case, two sheets of paper 4a stacked on top of each other
, 4b are the frictional forces acting between the driving roller 1.2, the outer peripheral surface of both rollers 1.2 and the surface of each paper 4a, 4b, and the frictional force acting between the driven roller 2 and the pivot @3. Since the torque is much weaker than the torque of the torque limiter 19 provided, both papers 4a
, 4b slide against each other, and only the paper 4a that is in direct contact with the rubber tube covering the outer peripheral surface of the drive roller 1 is sent rearward.
The paper 4b that has come into contact with the outer peripheral surface of the driven roller 2 is sent back forward (to the right in FIG. 14) by the driven roller 2, which rotates in the same direction as the pivot 3, and the two sheets of paper are separated.

By the way, as a torque limiter 19 for the driven roller installed between the pivot shaft 3 and the driven roller 2 of the above-mentioned automatic paper feeder, a torque limiter 19 as disclosed in Japanese Patent Laid-Open No. 62-80311 etc. has been conventionally used. A friction material such as felt or leather and a metal material are brought into contact with each other by the elasticity of a spring, and the desired torque is obtained by the frictional force acting between the friction material and the metal material. has been done.

(Problems to be Solved by the Invention) However, in the case of the torque limiter for a driven roller that obtains a desired torque by frictional force as described above, the following disadvantages occur.

First of all, when used for a long period of time, the obtained torque fluctuates as the friction material wears, and the performance of an automatic paper feeder or the like incorporating a torque limiter tends to become unstable.

Second, after the torque limiter is activated, it takes a considerable amount of time until the desired torque can be obtained, and during that time, the performance of an automatic paper feeder or the like incorporating the torque limiter is likely to become unstable.

Thirdly, if the friction material generates heat and its temperature rises as it is used, or if the usage conditions such as the installation location are special, it may not only have a negative impact on surrounding electronic devices, but also As the coefficient of friction fluctuates, the performance of automatic paper feeders and the like incorporating a torque limiter tends to become unstable.

In order to eliminate this inconvenience,
Publication No. 4 discloses a torque limiter that obtains a desired torque by the shearing force generated in magnetic powder held by a permanent magnet, but since the shearing force generated in the magnetic powder is unstable, it is difficult to obtain a desired torque. The torque generated also tends to be unstable.

The driven roller torque limiter of the present invention eliminates all of the above-mentioned disadvantages.

(Means for Solving the Problems) The torque limiter for a driven roller of the present invention includes a pivot shaft that is provided parallel to a drive shaft for rotationally driving the drive roller and rotates in the same direction as the drive shaft; It is provided between the roller housing and the roller housing having a cylindrical inner circumferential surface surrounding the pivot shaft, and regulates the torque when the driven roller rotates with respect to the pivot shaft.

In the case of the torque limiter for a driven roller according to claim 1, the torque limiter is made of a magnetic material in a circular ring shape and is fixed to the outer circumferential surface of the pivot shaft or the inner circumferential surface of the roller housing, which is covered at least on the surface with a non-magnetic material. at least one pair of ball pieces, a permanent magnet magnetized in the axial direction and clamped and fixed between the pair of ball pieces, and a peripheral edge and at least a surface of each ball piece made of a magnetic material. It consists of a magnetic fluid held between the covered outer circumferential surface of the pivot shaft or the inner circumferential surface of the roller housing, and a bearing that supports the roller housing concentrically and rotatably with respect to the pivot shaft.

Further, in the case of the torque limiter for a driven roller according to claim 2, the magnet is magnetized in the axial direction, and the outer circumferential surface of the pivot shaft or the inner circumferential surface of the roller housing is magnetized in the axial direction, and at least the surface is covered with a non-magnetic material. A fixed permanent magnet, a magnetic fluid held between the circumferential surface of both ends of the permanent magnet and the inner circumferential surface of a roller housing or the outer circumferential surface of a pivot whose surface is covered with a magnetic material at least, and the roller housing. The shaft is constructed from a bearing that supports the shaft concentrically and rotatably with respect to the pivot shaft.

(Function) In the case of the torque limiter for a driven roller of the present invention configured as described above, the periphery of the pair of ball pieces or the periphery of both ends of the permanent magnet, the outer periphery of the pivot shaft, or the inner periphery of the roller housing At the same time, an attractive force is applied between the magnetic fluid and the magnetic fluid held between the edge of the bow piece or the circumferential surface of both ends of the permanent magnet, and the outer circumferential surface of the pivot or the inner circumferential surface of the roller housing. A magnetic field is created in this state, and this magnetic fluid is firmly held in the intermediate portion and tends to remain in that state unless an external force is applied.

In this state, when the roller housing is rotated in the twisting direction relative to the pivot, the peripheral edges of the pair of ball pieces or the peripheral surfaces of both ends of the permanent magnet and the inner peripheral surface of the roller housing or the outer peripheral surface of the pivot By applying a shearing force to the magnetic fluid that is firmly held between the magnetic material that covers the , torque is generated in the torsional direction.

In this case, since the magnetic fluid is held by the strong magnetic field that exists between the ball piece and the roller housing, the viscosity of the magnetic fluid is much higher than the viscosity that it appears to be. will have. Therefore, the shearing force is much larger than that caused by the inherent viscosity of the magnetic fluid.

The relative rotation between the pivot shaft and the roller housing is guaranteed by the bearing, and since there is no friction between the pair of ball pieces or permanent magnets and the roller housing or pivot shaft, there is no friction between the pivot shaft and the roller housing. Torque is stable from the beginning, and there is no heat generation or wear associated with the use of a torque limiter, so stable performance can be obtained over a long period of time.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

1 and 2 show a first embodiment of the invention as claimed in claim 1, FIG. 1 is a sectional view showing the overall configuration, and FIG. 2 is a sectional view showing the state of formation of a magnetic field. It is an enlarged view of part A.

The outer peripheral surface of the pivot shaft 3 made of a non-magnetic material such as aluminum or synthetic resin is formed in a circular ring shape, and
Permanent magnets 5 mutually magnetized in the left-right direction in the figure are fitted and fixed on the outside.

Further, a pair of ball pieces 6.6 made of a magnetic material such as iron in a circular ring shape are fitted and fixed on both sides of the permanent magnet 5, and the pair of ball pieces 6.6 are used to secure the permanent magnet 5. A magnet 5 is held between them.

Further, on both sides of the pair of ball pieces 6.6, slide bearings 7.7 made of a slippery non-magnetic material such as nylon or Duracon are fitted in an annular shape, and each slide bearing 7
．． The inner peripheral surface of the shaft 7 and the outer peripheral surface of the pivot shaft 3 can be slid freely.

Further, a roller housing 8 formed in a short cylindrical shape from a magnetic material such as iron is fitted onto both sliding bearings 7.7.
The inner circumferential surface of both ends of the roller housing 8 and the outer circumferential surface of each slide bearing 7.7 are bonded to each other with an adhesive, so that each slide bearing 7.7 and the roller housing 8 are coupled and fixed.

The outer diameter of the pair of ball pieces 6.6 is made slightly smaller than the inner diameter of the roller housing 8 and the outer diameter of the slide bearing 7.7, so that the outer diameter of each slide bearing 7.7 and the roller housing 8 are slightly smaller. A gap 9.9 is formed around the entire circumference of each ball piece 6.6. Then, into each gap 9.9, a magnetic fluid 10.10 made of fine magnetic powder dispersed in oil such as silicone oil is injected,
This magnetic fluid 10.10 is moved by the magnetic force of the permanent magnet 5,
It is held within each gap 9.9.

In the case of the torque limiter for a driven roller of the present invention configured as described above, the roller housing and the outer periphery of a pair of ball pieces 6.6 fixed to the outer periphery of the pivot shaft 3 with the permanent magnet 5 sandwiched therebetween. 8, a magnetic field 11 as shown in FIG. 2 is formed according to the magnetic force of the permanent magnet 5. This magnetic field 11 causes magnetic flux to concentrate between the outer circumferential edge of each ball piece 6.6 and the inner circumferential surface of the roller housing 8, and the magnetic fluid 10.10 flows between the outer circumferential edge of each ball piece 6.6 and the roller housing 8. It is firmly held within the gap 9.9 between the inner circumferential surface of 8 and tends to maintain that state unless an external force is applied.

In this state, based on the sliding movement between the inner circumferential surface of the slide bearing 7.7 and the outer circumferential surface of the pivot shaft 3, as well as the sliding movement between the inner surface of each slide bearing 7.7 and the outer surface of the ball piece 6.6, When the roller housing 8 is rotated in the torsional direction with respect to the pivot 3, the magnetic fluid 10.1 firmly held between the outer peripheral edge of the pair of ball pieces 6.6 and the inner peripheral surface of the roller housing 8 is released.
By applying a shear force to 0, a pair of ball pieces 6.
Torque in the twisting direction is generated between the pivot shaft 3 supporting the roller housing 8 and the roller housing 8. As mentioned above, the shearing force in this case becomes sufficiently large due to the presence of the magnetic field.

Relative rotation between the pivot shaft 3 and the roller housing 8 is controlled by a pair of sliding bearings 7 provided with the ball piece 6.6 in between.
．． 7, and since the outer peripheral edge of the pair of ball pieces 6.6 and the inner peripheral surface of the roller housing 8 do not rub against each other, the torque generated between the pivot shaft 3 and the roller housing 2 is It is stable and does not generate heat or wear due to the use of a torque limiter, so stable performance can be obtained over a long period of time.

Next, FIG. 3 is a sectional view showing a second embodiment of the invention set forth in claim 1.

In the case of this embodiment, the pivot shaft 3 is made of a magnetic material such as iron, and therefore, in order to fix the pair of ball pieces 6.6 to the pivot shaft 3, a support made of a non-magnetic material is used. Cylinder 12
This is done through.

That is, a support tube 12 made of a non-magnetic material is fitted and fixed on the outer peripheral surface of the intermediate portion of the pivot shaft 3, and a permanent magnet 5 and a pair of ball pieces 6, 6 are further attached to the outer peripheral surface of the support tube 12. and are fixed externally. The other configurations and operations are the same as those of the first embodiment described above, so the same parts are given the same reference numerals and redundant explanations will be omitted.

Next, FIGS. 4 and 5 show a third embodiment of the invention described in claim 1, FIG. 4 is a sectional view showing the overall configuration, and FIG. FIG. 1 is an enlarged view of part B in FIG.

In the case of this embodiment, as shown in FIG.
．． 5 is held between three ball pieces 6.6, so that a magnetic field 11.11 as shown in FIG. 5 is formed between each ball piece 6.6 and the roller housing 8. ,
The torque acting between the pivot shaft 3 and the roller housing 8 is made to be large.

Other configurations and operations are the same as in the first embodiment described above, so equivalent parts are given the same reference numerals and redundant explanations will be omitted.

Incidentally, the work of injecting the magnetic fluid 10.10 into the gap 9.9 existing in the space closed at both ends by the sliding bearing 7.7 is performed as shown in FIG. 6 or 7, for example. Let's do it.

First, in the case of the method shown in FIG. 6, the injection needle 14 provided in the dispenser 13 (syringe) is inserted into the gap 9.
The magnetic fluid 10.10 is injected into the gap 9.9 through the injection needle 14.

Moreover, in the case of the method shown in FIG.
A small hole 16 is formed in the middle part of the permanent magnet 5, and a passage 17 is formed in a part of the permanent magnet 5 to communicate the small hole 16 with the outer peripheral surface of the permanent magnet 5.
The magnetic fluid 10 sent out from the small hole 16 and the passage 17
It is made so that it can be fed into the gap 9.9 through.

In either case, the magnetic fluid 10.10 sent to the vicinity of the gap 9.9 is attracted to the gap 9.9 by the magnetic force of the permanent magnet 5 and is firmly held in the gap 9.9. It will be like that.

Next, FIG. 8 is a sectional view showing a fourth embodiment of the invention set forth in claim 1.

In the case of this embodiment, the permanent magnet 5 and a pair of ball pieces 6.6 sandwiching the permanent magnet 5 are fitted and fixed in a roller housing 8 made of a non-magnetic material.

The inner diameter of each ball piece 6.6 is formed slightly larger than the outer diameter of the pivot shaft 3 made of magnetic material, and the magnetic fluid 10, 10
is held in a gap 9.9 formed between the inner peripheral edge of each ball piece 6.6 and the outer peripheral surface of the pivot shaft 3.

In the case of this embodiment as well, regarding other configurations and functions,
Since this is the same as in the first embodiment described above, the same parts are given the same reference numerals and redundant explanation will be omitted.

Next, FIGS. 9 to 12 show a fifth embodiment of the invention described in claim 1, in which FIG. 9 is a cross-sectional view of the roller housing, and FIG. 10 is a cross-sectional view taken along the line CC in FIG. 11 is a side view of the ball piece, and FIG. 12 is a sectional view showing the assembled state.

In the case of this embodiment, gear-shaped unevenness is formed on the outer circumferential edge of each ball piece 6.6 and the portion of the inner circumferential surface of the roller housing 8 where these outer circumferential edges face each other, and the gap 9.9 is A portion of the magnetic fluid 10.1° to be held is made to mesh with these irregularities.

Therefore, it is possible to increase the torque when the pivot shaft 3 and the roller housing 8 are mutually displaced in the twisting direction without particularly increasing the magnetic force of the permanent magnet 5.

Furthermore, FIG. 13 shows an embodiment of the invention set forth in claim 2.

In the case of this embodiment, a permanent magnet 5 formed in a cylindrical shape and magnetized in the axial direction is fitted and fixed on the pivot shaft 3 made of a non-magnetic material, and the outer circumferential surface of both ends of the permanent magnet 5 is fixed. , a magnetic fluid 10 is disposed between the inner peripheral surface of both ends of the roller housing 8 made of magnetic material.
．． Holds 10.

Also in the case of this embodiment, the roller housing 8 and the pivot shaft 3 are
They are rotatably combined by a pair of sliding bearings 7.7, and when both members 8.3 are displaced in the twisting direction, a torque corresponding to the magnetic force of the permanent magnet 5 is generated.

(Effects of the Invention) The torque limiter for driven rollers of the present invention is constructed and operates as described above, and therefore not only can stable torque be obtained from the beginning, but also heat generation and wear occur with use. Since there is no problem, stable performance can be obtained over a long period of time without adversely affecting surrounding equipment.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the invention as claimed in claim 1, FIG. 1 is a sectional view showing the overall configuration, and FIG. 2 is a sectional view showing the state of formation of a magnetic field. FIG. 3 is a sectional view showing a second embodiment of the invention stated in claim 1, and FIGS. 4 and 5 show a third embodiment of the invention stated in claim 1. Figure 4 is a sectional view showing the overall configuration, and Figure 5 is a sectional view showing the overall configuration.
The figures are an enlarged view of part B of Fig. 4 and Fig. 6 showing the state of magnetic field formation.
7 are sectional views showing two examples of the method of injecting magnetic fluid, FIG. 8 is a sectional view showing a fourth embodiment of the invention as claimed in claim 1, and FIGS. 9 shows a sectional view of the roller housing, FIG. 10 shows a sectional view taken along line CC in FIG. 9, and FIG. 11 shows a side view of the ball piece. , FIG. 12 is a cross-sectional view showing an assembled state, FIG. 13 is a cross-sectional view showing an embodiment of the invention described in claim 2, and FIG. 14 is a torque limiter for a driven roller, which is an object of the present invention. It is a side view of the separation mechanism incorporating. 1: Drive roller, 2: Followed roller, 3: Pivot, 4a, 4
b = paper, 5: permanent magnet, 6: ball piece, 7: sliding bearing, 8: roller housing, 9: gap, 10: magnetic fluid, 11: magnetic field, 12: support tube, 13: dispenser, 1
4: Injection needle, 15.16: Small hole, 17: Passage, 18: Drive shaft, 19° torque limiter.

Claims (2)

[Claims] (1) Provided between a pivot shaft provided parallel to a drive shaft for rotationally driving the drive roller and rotating in the same direction as the drive shaft, and a roller housing having a cylindrical inner circumferential surface surrounding the pivot shaft, A torque limiter for a driven roller that regulates the torque when the driven roller rotates with respect to a pivot shaft.The torque limiter is made of a magnetic material in a circular ring shape, and is made of a magnetic material to limit the torque when the driven roller rotates relative to a pivot shaft. at least one pair of ball pieces fixed to an inner circumferential surface; a permanent magnet magnetized in the axial direction and clamped and fixed between the pair of ball pieces; and at least a peripheral portion of each ball piece. A magnetic fluid is held between the inner circumferential surface of the roller housing whose surface is covered with a magnetic material or the outer circumferential surface of the pivot shaft, and a bearing that supports the roller housing concentrically and rotatably with respect to the pivot shaft. Torque limiter for driven rollers. (2) Provided between a pivot shaft that is provided parallel to a drive shaft for rotationally driving the drive roller and rotates in the same direction as the drive shaft, and a roller housing having a cylindrical inner circumferential surface surrounding this pivot shaft, A torque limiter for a driven roller that regulates the torque when the driven roller rotates with respect to a pivot shaft, the outer peripheral surface of the pivot shaft being magnetized in the axial direction and covered at least on the surface with a non-magnetic material. A permanent magnet fixed to the inner circumferential surface of the roller housing, and a permanent magnet held between the circumferential surfaces of both ends of the permanent magnet and the outer circumferential surface of a pivot whose surface is covered at least with a magnetic material or the inner circumferential surface of the roller housing. A torque limiter for a driven roller, comprising a magnetic fluid and a bearing that rotatably supports a roller housing concentrically with respect to a pivot.