JPH038808Y2 - - Google Patents

Description

[Detailed description of the invention] This invention transmits rotational force from the input shaft to the output shaft by controlling the tightening force of the coil spring wound from the input shaft to the output shaft.
This invention relates to improvements in so-called spring clutches that can be turned on and off, and in particular to spring clutches aimed at improving the positioning accuracy of the output shaft.

FIG. 1 shows a side sectional view of an example of a conventional spring clutch. In this case, the shaft 1 is coaxially and integrally attached to the output shaft 2, and the input shaft 4 is rotatably mounted on the small diameter portion 3 at the tip of the shaft 1.

Therefore, the output shaft 2 and the input shaft 4 are coaxial and rotatable separately, and both have outer peripheral portions 5 and 6, respectively, having the same outer diameter. A series of coil springs 7 are wound around both outer circumferential parts 5 and 6 so as to tightly contact (tighten freely) to both outer circumferential parts 5 and 6.
One end 8 of this coil spring 7 is connected to the output shaft 2
It is fitted into an insertion hole 9 drilled in the direction of the axis of the shaft 1 and fixed to the output shaft 2.

Also, the coil spring 7 has a slight gap 1.
The clutch control tube 11 is accommodated in the inner diameter portion 12 of the clutch control tube 11, which is loosely fitted to the outer circumferential portion of the clutch control tube 11 via the clutch control tube 11. It is fixed to the clutch control cylinder 11 by being fixed to the clutch control cylinder 11.

The gear 15 is for transmitting power to the input shaft 4, and is fixed to the input shaft 4 by a key 16 as shown.

In the case of this spring clutch, it is important that the direction in which the coil spring 7 is wound around the input shaft 4 and output shaft 2, and that the coil spring 7 is tightly wound around the input shaft 4 and output shaft 2. Regarding the above-mentioned winding direction, when the input shaft 4 is rotated in a certain direction with a load applied to the output shaft 2 in Fig. 1, the input shaft 4
The coil spring 7 tightly wound around the input shaft 4 is twisted around the input shaft 4 by the frictional force with the input shaft 4, and due to this twisting, the coil spring 7
This direction is such that the inner diameter of the input shaft 4 is reduced, the outer circumference 6 of the input shaft 4 and the outer circumference 5 of the output shaft 2 are further tightened, and the rotational force of the input shaft 4 is transmitted to the coil spring 7.

This spring clutch has a claw 17 protruding from a fixed position on the outer periphery of the clutch control cylinder 11, and this claw 17 is connected to a hook member that swings around a support shaft 18 outside the clutch, as shown in FIG. 1
9 is oscillated by a solenoid 20 or the like, and the hook member 19 engages with the pawl 17 to forcibly stop the rotation of the clutch control cylinder 11.

Now, suppose gear 1 is loaded with output shaft 2.
5 is rotationally driven in the clockwise direction (direction shown by arrow 21) when viewed from the direction of arrow A shown in FIG. 1, and as mentioned above, the coil spring 7 rotates around this input shaft 4.
Due to the rotation of the outer peripheral part 6 of the input shaft 4 and the output shaft 2
The rotation of the input shaft 4 is transmitted through the coil spring 7 to the output shaft 2, which is fixed to the coil spring 7 by its one end 8. The shaft 1 fixed to the shaft 2 rotates in the direction indicated by the arrow 21 at the same rotation speed as the gear 15.

In such a rotation transmission state (the clutch is ON), the solenoid 20 shown in FIG. This is the same as rotating the other end 13 of the coil spring 7 fixed to the clutch control cylinder 11 relative to the input shaft 4 in the direction opposite to the direction indicated by the arrow 21. It has the same effect as rotating the other end 13 in the direction of loosening the coil spring 7 wound around the outer periphery 6 of the input shaft 4, and this action expands the inner diameter of the coil spring 7. The coupling force between the inner diameter part and the outer circumference part 6 of the input shaft 4 is loosened, and the coupling between the input shaft 4 and the coil spring 7 is broken (clutch
OFF state), the rotation of the input shaft 4 is no longer transmitted to the coil spring 7, and the output shaft 2 stops.

Such a spring clutch is installed, for example, in a drive source for a cam that presses and separates a fixing roller in a copying machine, and is generally used when the clutch is turned on.
Or, the positioning accuracy of the rotational position of the output shaft 2 or shaft 1 when switching to the OFF state is extremely important, especially when it is necessary to time the start and stop, such as the fixing roller used in a copying machine. Adjustment of the mounting position of the output shaft 2 via the coil spring 7 with respect to the position of the pawl 17 is extremely important.

However, as mentioned above, in conventional spring clutches, it is generally extremely difficult to finish the inner diameter of the coil spring 7 with high precision. There is a problem in that a positional deviation occurs between the clutch and the clutch 13, resulting in variations in timing when the clutch is operated.

This is because, as mentioned above, the coil spring 7 is
Since the coil spring 7 must be in close contact with the input shaft 4 when attached to the input shaft 4, the inner diameter of the coil spring 7 is set to the input shaft 4 at the time of manufacture.
This is because the coil spring 7 is manufactured to have a slightly smaller diameter than the outer diameter of the coil spring 7, and the error in the inner diameter of the coil spring 7 cannot be ignored.

For example, consider the case where the coil spring 7 is manufactured with the goal that when the input shaft 4 is fitted onto the coil spring 7, one end 8 and the other end 13 of the coil spring 7 are in the same phase. FIG. 3 is a diagram showing the positional relationship between one end portion and the other end portion 13 of the coil spring 7 in such a fitted state.

In order for both ends 8 and 13 of the coil spring 7 to be in the same phase position when the input shaft 4 is inserted, the inner diameter of the coil spring 7 when removed from the input shaft 4 as shown in FIG. Third
The inner diameter of the coil spring 7 is smaller than the inner diameter of the coil spring 7 when the input shaft 4 is inserted as shown in Figure a, and the positions of one end 8 and the other end 13 of the coil spring are shifted by an angle α. Therefore, when manufacturing the coil spring 7, both ends 8 and 13 must be bent with an angle α corresponding to this amount of deviation taken into account from the beginning.

However, as mentioned above, the inner diameter of the coil spring 7 varies considerably depending on manufacturing conditions, so if the input shaft 4 is fitted into the coil spring 7 whose inner diameter is set relatively small, the inner diameter will not match the designed dimension. The inner diameter of the coil spring 7 is larger than that of the coil spring 7 manufactured in
The coil spring 7 is expanded to the position 8a past the point in phase with , and the position of the pawl 17 of the clutch control tube 11 and the stop position of the output shaft 2 are changed by the angle β of the deviation due to this extra expansion. A discrepancy occurs between the two. The deviation angle β from the planned position is the deviation angle for one turn of the coil spring 7, and since an actual coil spring consists of a large number of pitches, this deviation angle β increases in proportion to the number of turns. However, in the end, a slight error in the inner diameter of the coil spring 7 is greatly amplified and becomes a positioning error between the clutch control cylinder 11 and the output shaft 2.

Such an error similarly occurs when the inner diameter of the coil spring 7 is larger than the design target value, but the direction of the deviation angle β due to this error is opposite to that shown in Fig. 3b. It is.

Furthermore, in the conventional spring clutch shown in FIG. 1, the insertion hole 9 into which the one end 8 of the coil spring 7 is fitted must be bored in a direction parallel to the shaft 1 for convenience of assembling the clutch. The spring 7 cannot be fixed to the output shaft 2 in a direction parallel to the shaft 1, and it is impossible to prevent the coil spring 7 from shifting in the direction of the gear 15.

The spring clutch shown in FIG. 8 is designed to improve the positioning accuracy of the output shaft 2.
A series of coil springs connects the input shaft 4 and the output shaft 2 so that they can rotate coaxially and independently, and are housed in the clutch control inner cylinder 11a from the outer periphery of the input shaft 4 to the outer periphery of the output shaft 2. At the same time, one end 8 of the coil spring 7 is fixed to the output shaft 2, and the other end 13 is fixed to the clutch control inner cylinder 11a.
A clutch control outer cylinder 11b whose mounting angle with respect to the clutch control inner cylinder 11a is variable is fixed to the clutch control inner cylinder 11a, and the other end of the coil spring 7 is connected to the clutch control outer cylinder 11b via the clutch control inner cylinder 11a. It is a spring clutch fixed to.

In this conventional example, the clutch control cylinder 11 shown in FIG. 1 is divided into a clutch control inner cylinder 11a and a clutch control outer cylinder 11b.
After positioning the clutch control inner cylinder 11a
can be turned to a position that absorbs the error of the coil spring 7 and fixed to the clutch control outer cylinder 11b with the set bolt 25a, and the stopping position of the output shaft 2 can be accurately determined regardless of the size of the error in the circumference of the coil spring 7. It is excellent in that it allows decisions to be made.

However, in order to assemble the spring clutch according to this embodiment, the operator must first support the clutch control inner cylinder 11a in a predetermined position with his hands, and in that state, use his other hand to turn the input shaft in the direction to loosen the coil spring 7. Loosen the spring, and at the same time, use another hand to loosen the clutch control outer cylinder 11.
Turn b to position it relative to the output shaft 2.

In this state, by releasing two of the three hands, the coil spring 7 will be in the closed state (the clutch control outer cylinder 11b and the output shaft 2 will be kept at the positions determined by), and in this state, the set bolt will be closed. 25a to complete the assembly.

The reason why the coil spring 7 is loosened by rotating the input shaft in this manner is to reproduce the actual driving state so that dimensional errors caused by loosening the coil spring 7 do not occur during actual driving.

Therefore, this conventional spring clutch requires three hands for operation, and has the drawback that the assembly work cannot be completed by one operator alone.

The purpose of the present invention is to eliminate the inconveniences and shortcomings inherent in the conventional spring clutch as described above, improve the positioning accuracy of the output shaft 2 when the clutch is operated, and simplify the assembly work. Its main structure is a clutch control tube that connects an input shaft and an output shaft so that they can rotate coaxially and independently, and that is housed in a clutch control cylinder from the outer periphery of the input shaft to the outer periphery of the output shaft. A spring clutch in which a coil spring is tightly wound, one end of the coil spring is fixed to an output shaft, and the other end is fixed to a clutch control cylinder, and the mounting angle with respect to the output shaft is variable. While fixing the positioning ring,
The present invention provides a spring clutch characterized in that one end of the coil spring is fixed to the output shaft via the positioning ring, and the mounting position of the positioning ring with respect to the output shaft can be adjusted as desired. The mounting position of the positioning ring can be adjusted according to the error in the inner diameter of the coil spring, and the error in the inner diameter of the coil spring can be absorbed. Since it is good (only requires two hands), the work can be completed by one operator.

Next, embodiments embodying the present invention will be described in detail with reference to the accompanying drawings from FIG. 4 onwards.

Here, FIG. 4 is a side sectional view of a spring clutch according to an embodiment of the present invention, FIG. 5 is a view taken in the direction of arrow B in FIG. 4, and FIG. 6 is an exploded perspective view of the spring clutch shown in FIG. 4. It is a diagram. Note that the same reference numerals are used for elements common to those of the spring clutch shown in FIG.

In the embodiment shown in FIGS. 4 to 6,
An annular groove 23 is carved in the surface of the output shaft 22 facing the clutch control cylinder 11, and an annular positioning ring 24 having the same cross-sectional shape as the groove 23 is fitted into this groove 23. The positioning ring is fixed to the output shaft 22 by a set bolt 25 threaded onto the output shaft 22 in the radial direction. However, when the set bolt 25 is loosened, the positioning ring 24 can be rotated within the groove 23 in the circumferential direction around the shaft 1.

Clutch control tube 11 of the positioning ring 24
A radial groove 26 is provided on the side surface 24a opposite to the
is engraved.

Further, the shape of the coil spring 27 is such that both ends thereof are bent at 90 degrees in the radial direction of the output shaft 22, and one of the bent ends is connected to the positioning ring 24.
is fitted into the groove 26 and fixed to the output shaft 22. Since the clutch control cylinder 11 is held between one end and the other end of the coil spring 27, the coil spring 27 and the clutch control cylinder 11 do not shift in the direction of the gear 15.

The order of assembling this spring clutch is to first fit the output shaft 22 onto the shaft 1 and secure it with a set bolt (not shown), and then, with the clutch control cylinder 11 fixed in a predetermined position with one hand, move the output shaft 22 onto the shaft 1. Use your other hand to hold coil spring 2.
7 in the direction of loosening. When the output shaft 22 has rotated to the specified position, release the clutch control tube 11 and the coil spring 27 will close. In this state, tighten the set bolt 25 to complete the assembly. By aligning the clutch control tube 11 and the output shaft 22 with the coil spring 27 loosened during assembly in this manner, the actual driving condition can be reproduced, and the circumferential length error that occurs when the coil spring 27 is loosened can be avoided. It is possible to avoid this.

By attaching the input shaft 4 to the inner diameter portion of the coil spring 27, the coil spring 27 is expanded, and the distance between one end 28 and the other end 13 of the coil spring 27 is increased by an angle corresponding to the error in the inner diameter. Although some displacement occurs, the positioning ring 24 can be fixed at any angle with respect to the output shaft 22 using the set bolts 25.
This deviation is simply due to the output shaft 22 of the positioning ring 24.
The output shaft 22 can be positioned at an appropriate angular position relative to the position of the other end 13 of the coil spring 27, that is, the position of the pawl 17 of the clutch control cylinder 11. , errors due to variations in the inner diameter of the coil spring 27 do not affect the control position of the output shaft 22 at all. Further, since the spring clutch can be assembled by one operator, the work cost can be reduced.

In the above embodiment, the pawl 17 that determines the stop position of the clutch control cylinder 11 is made to protrude from the outer periphery of the clutch control cylinder 11, but this is just an example. A groove may be formed on the outer periphery of the input shaft 4, and a brake pawl may be fitted into the groove.Also, the drive means for the input shaft 4 is not limited to the illustrated gear 15, etc. It is also conceivable that 4 itself constitutes the output shaft of a motor or the like, or that it is rotated by a chain, belt, or the like.

Furthermore, in order to visually confirm the position of one end 28 of the coil spring 27, a window 29 may be cut out in the outer circumference of the output shaft 22 as shown in FIG.

As described above, the present invention connects an input shaft and an output shaft so that they can rotate coaxially and independently, and a series of clutch control tubes housed in a clutch control cylinder extend from the outer periphery of the input shaft to the outer periphery of the output shaft. In a spring clutch in which a coil spring is tightly wound and one end of the coil spring is fixed to an output shaft and the other end is fixed to a clutch control tube, a spring is attached to the output shaft or the clutch control tube. This spring clutch is characterized in that a positioning ring with a variable mounting angle is fixed, and one end of the coil spring is fixed to the output shaft via the positioning ring. It is possible to position the clutch at a constant position with respect to the clutch control tube regardless of variations in the clutch control cylinder, and it is possible to significantly improve the positioning accuracy of the output shaft when the clutch is operated. This reduces the number of workpieces and contributes to a reduction in work costs. In addition, in the case of such a spring clutch, the responsiveness during clutch operation changes depending on the restoring force of the coil spring, so if there is a large variation in the inner diameter of the coil spring, the responsiveness between clutches will vary accordingly. However, in the case of the present invention, since the mounting angle of the output shaft relative to the coil spring can be adjusted arbitrarily, the output can be adjusted to the extent that this delay can be absorbed in advance in response to variations in clutch response time due to errors in the inner diameter of the coil spring. Since the clutch can be set on a coil spring with the shaft shifted, variations in clutch response can be minimized.

Furthermore, since the output shaft, positioning ring, coil spring, clutch control tube, and input shaft are arranged in a substantially coaxial direction, the output shaft is arranged in the radial direction of the input and output shafts. The diameter can be reduced, and the device can be made more compact.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional spring clutch, Figure 2 is a front view showing an example of a mechanism for braking the clutch control cylinder of the same spring clutch, and Figure 3 is an output shaft due to variations in the inner diameter of the coil spring. 4 is a front view of the coil spring seen from the direction of arrow A in FIG. 1, and FIG. Figure 5 is a BB arrow view in Figure 4, and Figure 6
The figure is an exploded perspective view of the spring clutch shown in FIG. 4, FIG. 7 is a sectional view taken along the line C--C in FIG. 4, and FIG. 8 is a side sectional view showing another example of the conventional spring clutch. Explanation of symbols, 4...Input axis, 22...Output axis,
DESCRIPTION OF SYMBOLS 11... Clutch control tube, 27... Coil spring, 28... One end, 13... Other end, 24...
...Positioning ring, 26...Groove, 25...Set bolt.

Claims (1)

[Scope of utility model registration request] An input shaft and an output shaft are connected coaxially and so that they can rotate independently, and a series of coil springs housed in a clutch control cylinder are tightly wound from the outer periphery of the input shaft to the outer periphery of the output shaft. In addition, in the spring clutch in which one end of the coil spring is fixed to the output shaft and the other end to the clutch control cylinder, a positioning ring whose mounting angle with respect to the output shaft is variable is fixed to the output shaft, and the positioning ring is fixed to the output shaft. A spring clutch characterized in that one end of the coil spring is fixed to the output shaft via a ring.