JPH0592541U - Spring clutch device - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the durability and prevent the generation of abnormal noise while enabling smooth transmission and interruption of rotational power. [Structure] The clutch hub 52 is formed of nylon 12 having elasticity and maintaining a constant surface roughness.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a spring clutch device suitable for being applied to industrial equipment such as a printer feed device.

[0002]

[Prior Art]

 First, a schematic configuration of a printer to which a conventional spring clutch device is applied will be described with reference to FIGS.

In these drawings, reference numeral 1 denotes a printing unit, which includes a platen 2 and a print head (not shown). A feeding device 10 is a means for feeding the paper P to the printing unit 1.

Here, the feed device 10 is composed of a feed roller 11, a pinch roller 12, conveyance rollers 13 and 14, a drive unit 15, and the like. Specifically, the feed roller 11 and the pinch roller 12 are formed so that the paper P can be nipped and conveyed in cooperation with each other. The drive unit 15 is a means for rotationally driving the feed roller 11, and includes a drive shaft 16, a gear 17, a drive motor (not shown), a spring clutch device 51, and the like. The drive shaft 16 is rotated by a drive motor via a gear 17 and the like. As shown in FIGS. 6 and 7, the spring clutch device 51 is a means for selectively transmitting and interrupting rotational power from the drive shaft 16 to the feed roller 11, and includes the clutch hub 52 and the spring. 53 and a ratchet member 54 are included.

The clutch hub 52 is made of iron and is fixed to the drive shaft 16 via spring pins 59 and the like. In addition, the spring 53 fastens the rotation of the drive shaft 16 by elastically tightening the tip end portion 52a of the clutch hub 52, one end portion 53a of which is fixed to the feed roller of the feed roller 11 and the other end portion 53b of which is fitted and engaged. It is formed so that it can be transmitted to the roller 11. Further, the ratchet member 54 covers the spring 53, and is made to be rotation lock and rotation free by a ratchet control means (not shown) to release the tightening of the spring 53 to the clutch hub 52 against the elastic force. It is formed so that both (52, 53) can be slid.

However, when the paper is fed using the printer, the drive motor is driven and the drive shaft 16 is rotationally driven via the gear 17 and the like. The ratchet member 54 engaged with the spring 53 is freed from rotation by the ratchet control means and rotates synchronously with the drive shaft 16 to transmit the rotational power of the drive shaft 16 to the feed roller 11. On the other hand, when printing, the rotation of the ratchet member 54 is locked by the ratchet control means. Then, the ratchet member 54 releases the tightening of the spring 53 with respect to the clutch hub 52 against the elastic force, and the two (52, 53) slide. As a result, the drive shaft 16 idles and the rotation of the feed roller 11 is stopped. In this state, one line (one line) is printed by the print head. When printing the next line, the feed roller 11 is rotated by one line using the spring clutch device.

[0007]

[Problems to be solved by the device]

 By the way, in the spring clutch device 51 having the above-described configuration, when the rotational power is transmitted, slippage occurs between the clutch hub 52 and the spring 53 after a relatively short period of use (for example, one million lines, about two weeks for store use). It may occur and is a big problem.

In addition, the sliding contact portion between the clutch hub 52 and the spring 53 may vibrate to generate an abnormal sound, which may give a discomfort to the user.

In view of the above circumstances, an object of the present invention is to provide a spring clutch device capable of smoothly transmitting and interrupting rotational power while improving durability and preventing abnormal noise.

[0010]

[Means for Solving the Problems]

 The present invention was created as a result of theoretically and experimentally investigating the cause of slippage between the clutch hub and the spring and the cause of abnormal noise.

First, a basic transmission torque formula for considering the cause of slippage is shown below (where, the following formula is obtained by assuming that the clutch hub is a perfect circle and a rigid body).

T ′ = [Rd / (Rf · Re ² )] · EIδ [exp (μφ) −1] where T ′: transmission torque (kg · cm), exp: base of natural logarithm, μ: sp Coefficient of friction with ring winding surface, φ: Spring wrap angle per axis (rad), φ = 2πn (n is the number of spring turns per axis), I: Moment of inertia of area (cm ⁴ ) of the spring , E: Modulus of longitudinal elasticity (kg / cm ² ), Rd: Radius of shaft (cm), Rf: Average radius of spring in free state (cm), Re: Average radius of spring under press fitting (cm), δ : The tightening margin (cm 2) of the radius between the spring and the shaft.

From the above equation, if μ of exp (μφ), that is, the coefficient of friction with the spring winding surface is reduced, the transmission torque T ′ is extremely reduced. This fact was confirmed by experiments. By the way, various experiments have revealed that the iron clutch hub has a mirror-finished surface (surface roughness of about 0.8 S) and a reduced friction coefficient in a relatively short period of use.

Therefore, a durability test was conducted by roughening the surface of the clutch hub, and it was found that the surface-treated portion was worn away at an early stage and was ineffective in preventing slippage.

Further, in order to prevent the generation of abnormal noise, an experiment was conducted by reducing the degree of sliding contact between the clutch hub and the spring when the drive shaft was spinning, but there was no effect.

Based on the above results, the present invention was devised with the idea that the occurrence of slippage and abnormal noise cannot be eliminated by external improvement, and internal improvement, that is, the material itself of the clutch hub needs to be reviewed. It was done.

That is, the spring clutch device according to the present invention is a spring clutch device that transmits and cuts off power from the drive shaft to the driven member, and includes a clutch hub fixed to the drive shaft and a driven member. A spring that transmits the power from the drive shaft to the driven member by tightening the clutch hub portion, one end of which is fixed and the other end of which is fitted and engaged, by elastic force, and the tightening of this spring on the clutch hub is resistant to the elastic force. The clutch hub is made of a material having elasticity and maintaining a constant surface roughness.

[0018]

[Action]

 In the present invention having the above structure, the surface roughness of the clutch hub does not change even after long-term use, and the friction coefficient remains constant. Therefore, the rotational power transmitted from the drive shaft to the driven member does not decrease over a long period of time, and no slippage occurs between the two. Further, since the clutch hub is elastic, the so-called biting of the spring when transmitting rotational power is better than that of the conventional iron clutch hub, and the transmitted power is increased.

Further, since the vibration generated in the sliding contact portion between the clutch hub and the spring is immediately absorbed by the elastic clutch hub, no abnormal sound is generated.

Therefore, it is possible to smoothly transmit / shut off rotational power while improving durability and preventing abnormal noise from occurring.

[0021]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. (First Embodiment) A spring clutch device according to this embodiment is applied to a feed device of a printer, and as shown in FIGS. 1 to 3, a drive shaft 16, a clutch hub 52, a spring 53, a spring control means. (54, 55) and driven member (feed roller 11), and the clutch hub 52 is made of a material having an elastic force and maintaining a constant surface roughness. The same or common components as those of the conventional example (FIGS. 6 to 8) are designated by the same reference numerals, and the description thereof will be omitted or simplified.

Here, the clutch hub 52 is formed of a material having elasticity and maintaining a constant surface roughness. In this embodiment, the clutch hub 52 is made of a resin material (nylon 12) having high elasticity and wear resistance so that the surface roughness of the tip portion 52a is 2S. Since this nylon 12 is also highly resistant to heat and oil, it is an optimal material for clutch hubs.

Further, as shown in FIG. 3, the ratchet control means is composed of a ratchet member 54 and a ratchet control means 55 capable of selectively bringing the ratchet member 54 into a rotation lock state or a rotation free state. There is. The ratchet control means 55 uses a lever 56 that can be engaged with each tooth of the ratchet member 54, a spring 58 for engaging the lever 56 with the ratchet member 54, and an elastic force of the lever 58 for the lever 56. It is configured to include an electromagnet 57 for separating it from the ratchet member 54.

Here, when the electromagnet 57 is excited, the lever 56 rotates clockwise and is positioned at the position indicated by the chain double-dashed line in the figure, and the rotation-locked state of the ratchet member 54 is released so that the ratchet member 54 becomes free. Become. When the electromagnet 57 is demagnetized, the lever 56 is returned to the position shown by the solid line in the figure by the elastic force of the spring 58, and the rotation of the ratchet member 54 is locked.

Next, the operation will be described. The clutch hub 52 formed of nylon 12 has a constant friction coefficient without changing the surface roughness even if it is used for a long period (equivalent to 10 million lines used in this embodiment). Therefore, the rotational power (T ') transmitted from the drive shaft 16 to the feed roller 11 does not decrease over a long period of time, and no slippage occurs between the two. Further, since the clutch hub 52 made of nylon 12 has elasticity, as shown in FIG. 2, the engagement of the spring 53 with the clutch hub 52 during transmission of rotational power is better than that of the conventional iron clutch hub. The transmitted power (T ') is increased.

Further, the vibration generated at the sliding contact portion between the clutch hub 52 and the spring 53 is immediately absorbed by the elastic clutch hub 52, so that no abnormal sound is generated. Since the diameter of the spring 53 slightly decreases with use, the tip portion 52a of the clutch hub 52 can be sufficiently tightened by the spring 53, and also from this point, the occurrence of slippage can be effectively prevented. ..

According to the first embodiment, however, since the clutch hub 52 is made of nylon 12 which has elasticity and maintains a constant surface roughness, durability is improved and abnormal noise is generated. Rotational power can be transmitted and cut off smoothly while preventing generation.

Second Embodiment A clutch hub, which is an essential part of the second embodiment, is shown in FIGS. 4 and 5. 4A is a front view of a clutch hub having straight groove portions, FIG. 4B is a right side view thereof, FIG. 5A is a front view of a clutch hub having spiral groove portions, and FIG. It is a right side view.

The spring clutch device according to the second embodiment has a configuration in which a groove portion 62 is provided on the outer peripheral surface of the tip end portion 52 a of the clutch hub 52. As shown in FIGS. 4A and 4B, the groove portion 62 is composed of a plurality of grooves 62a formed on the outer peripheral surface of the distal end portion 52a of the hub 52 by a predetermined pitch parallel to the axis of the hub 52. There is. The groove portion 62 may be composed of a groove 62b spirally formed on the outer peripheral surface of the tip portion 52a as shown in FIGS. 5 (A) and 5 (B).

With this structure, the friction coefficient of the outer peripheral surface of the tip portion 52a of the clutch hub 52 is increased as compared with the first embodiment. As a result, the so-called biting of the spring 53 at the time of transmitting the rotational power becomes much better than that of the first embodiment, and the transmitted power is greatly increased.

Further, particularly in the second embodiment, oil (grease or the like containing organic molybdenum) is applied to the outer peripheral surface of the tip portion 52a of the clutch hub 52. The applied oil (such as grease) is retained by the groove portion 62 for a long period of time without falling off from the clutch hub 52, and effectively prevents the outer peripheral surface of the tip portion 52a of the hub 52 from being worn away. .. As a result, the durability is further improved. Further, the reduction of the biting force (transmitted power) is prevented more effectively. Further, the vibration generated in the sliding contact portion between the clutch hub 52 and the spring 53 is more quickly absorbed by the elasticity of the hub 52 and the applied oil, and the generation of abnormal sound is further effectively prevented.

Although the present invention is applied to the feed device of the printer in the first and second embodiments, it may be applied to other industrial equipment.

[0033]

[Effect of the device]

 According to the present invention, since the clutch hub is made of a material having elasticity and a constant surface roughness, the rotational power is transmitted smoothly while improving durability and preventing abnormal noise.・ Can be shut off.

[Brief description of drawings]

FIG. 1 is a half sectional view for explaining an essential part of a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an engagement state between a clutch hub and a spring.

FIG. 3 is likewise a view showing a spring control means.

FIG. 4 is a view showing a clutch hub which is a main part of the second embodiment.

FIG. 5 is a diagram for explaining a modified example of the groove portion formed in the clutch hub.

FIG. 6 is an overall configuration diagram showing a conventional spring clutch device.

FIG. 7 is an exploded perspective view for explaining details of a conventional spring clutch device.

FIG. 8 is a diagram showing a printer to which a conventional spring clutch device is applied.

[Explanation of symbols]

 11 Feed Roller (Driven Member) 16 Drive Shaft 52 Clutch Hub 53 Spring 54 Ratchet Member (Spring Control Means) 55 Ratchet Control Means (Spring Control Means)

Claims (1)

[Scope of utility model registration request] 1. Transmission of power from a drive shaft to a driven member
A spring clutch device for disconnecting a drive shaft, wherein a clutch hub fixed to a drive shaft and a clutch hub part having one end fixed to a driven member and fitted and engaged at the other end are tightened by elastic force. From the driven member to the driven member, and spring control means for releasing the tightening of the spring with respect to the clutch hub against the elastic force and sliding the two, and the clutch hub has elasticity. A spring clutch device, which is formed of a material whose surface roughness maintains a constant value.