JP2991763B2 - Overload protection device - Google Patents

Description

The present invention relates to an overload protection device provided on a torque transmission arm.

<< Conventional Technology >> Generally, an arm for transmitting torque is often used. For example, a simple example of this torque transmitting arm is a link of a link mechanism or a torque wrench.

In addition to the above, there is a cam type pick-and-place device disclosed in Japanese Utility Model Laid-Open Publication No. 1-1830, which uses the torque transmission arm.

The cam-type pick and place device is a device that converts input shaft rotation into axial reciprocating motion and rotational motion and transmits it to an output shaft. Is used.

That is, each of the cam mechanisms has a predetermined geometric curve, is provided with a cam groove and a taper rib rotated by the input shaft, and the conversion into reciprocating motion is performed through a swing arm guided by the cam groove. At the same time, the conversion into the rotational motion is performed through a cam follower that is slidably contacted with the tapered rib.

In other words, the swing arm that converts the reciprocating motion has a fulcrum provided at the base end pivotally attached to the housing,
A force point provided at the intermediate portion is fitted into the cam groove, and an action point provided at the free end is engaged with the output shaft.

The swing arm is swung about a fulcrum with the rotation of the cam groove, and the output shaft is reciprocated in accordance with the swing angular displacement at this time. The torque generated in the moving arm is also transmitted to the output shaft as the reciprocating movement force of the output shaft.

Therefore, the swing arm also has a function as a torque transmission arm.

<< Problems to be Solved by the Invention >> However, such a conventional swing arm is simply formed in a rigid body, and the swing power, that is, the torque of the swing arm can be reliably transmitted to the output shaft.

However, if the movement of the output shaft is hindered by any obstacle during the reciprocating movement of the output shaft, an excessive load acts on the swing arm, causing a failure.

Therefore, conventionally, an overload absorbing member such as a spring or a hydraulic or pneumatic piston has been interposed in the power transmission path from the input shaft to the output shaft via the swing arm to absorb the overload. .

However, in the case where the overload absorbing member is interposed as described above, the rigidity of the power transmission path is reduced to cause vibration, and a device for absorbing the overload becomes complicated, resulting in cost reduction. There was a problem that was forced to up.

In view of such a conventional problem, the present invention can reliably absorb an overload with a simple configuration, and furthermore, in a predetermined load state until the overload occurs, the rigidity of the power transmission path is reduced. An object is to provide an overload protection device that can be maintained at a high level.

<< Means for Solving the Problems >> In order to achieve such an object, the present invention provides a bending arm having a leaf spring function by connecting a power point side portion and an action point side portion of a torque transmission arm, The power point side branch arm and the load point side branch arm protruding from the load point side portion and the load point side portion, respectively, and the distal ends of the load point side branch arm and the load point side branch arm are bent. And a detachable locking portion provided on the overlapping portion, which is overlapped on the side of the arm, wherein the locking portion is disengaged when a predetermined torque or more acts on the torque transmission arm. And

<Operation> With the above configuration, in the overload protection device of the present invention, in the normal torque transmission state, the locking portion between the power point side branch arm and the application point side branch arm is engaged. Therefore, the rigidity of the torque transmission arm is set high.

On the other hand, when a torque equal to or more than a predetermined value acts on the torque transmission arm, the locking portion is disengaged, and the force-point-side branch arm and the application-point-side branch arm are moved relative to each other.

For this reason, the power point side portion and the action point side portion of the torque transmission arm are substantially connected only by the bending arm, and the overload is absorbed by the bending deformation of the bending arm portion.

Further, when the overload is removed, the bending arm is returned to the original state by a spring action, and when the bending arm is returned in this manner, the locking portion is re-engaged to return to a normal torque transmission state. can do.

<< Example >> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 to 3 show one embodiment of the present invention,
FIG. 1 is a front view of a single torque transmission arm 10 provided with an overload protection device, FIG. 2 is an explanatory view showing a state where the torque transmission arm 10 is engaged with an output shaft, and FIG. 3 is a torque transmission arm. FIG. 10 is an explanatory diagram showing an operating state of the apparatus 10;

The torque transmitting arm 10 is applied to, for example, an oscillating handler. As shown in FIG. 1, a lower end in the figure is attached to an input shaft 12 and is rotated integrally therewith. The portion is a power point side portion 14.

A locking pin 18 to be engaged with the output shaft 16 shown in FIG. 2 is fixedly provided at the upper end of the torque transmission arm 10 in the drawing. Side part
It is 20.

A center line L connecting the center of the input shaft 12 and the center of the locking pin 18 is formed between the power point side portion 14 and the action point side portion 20.
Above, a bending arm 24 for connecting the force point side portion 14 and the action point side portion 20 is arranged.

The bending arm 24 exerts a leaf spring action against the direction of torque action, that is, deformation in the lateral direction of the paper surface in FIG. 1, that is, the bending arm 24 is formed to have a small thickness. When the bending stiffness is set to be small and the torque to be transmitted by the torque transmission arm 10 acts on both ends of the bending arm 24 without being transmitted to a branch arm described later, the bending arm 24 It is largely bent in the left-right direction inside and elastically deformed.

The torque transmission arm 10 includes the power point side portion 14.
And the direction of torque action of the bending arm 24 from the action point side portion 20, that is, the force point side branch arm 2
6, 26a and the application point side branch arms 28, 28a are protruded, respectively. Locking portions 32, 32a which are superposed on each other and which can be disengaged are provided between the respective superposed portions 30, 30a.

Further, the force point side branch arms 26, 26a and the action point side branch arms
The overlapping tip portions of 28 and 28a are respectively set on the center line L located on the bending arm 24 and are formed in an arc shape with an arbitrary point 0 as the center. Here, in the illustrated embodiment, the locking portions 32 and 32a are disposed opposite to each other at a position orthogonal to the center line L, and the intersection of the line connecting these and the center line L is a branch arm. It coincides with the arc center 0 of the overlapping portion.

The locking portions 32, 32a are provided with engaging recesses 34, 34a formed outside the force-point side branch arms 26, 26a, and the action point-side branch arms 28, It is constituted by engaging projections 36, 36a formed inside 28a.

The engagement protrusions 36, 36a are each formed in a hemispherical shape, and the engagement between the engagement protrusions 36, 36a and the engagement recesses 34, 34a is such that a predetermined excessive torque is applied to the torque transmission arm 10. It is set in advance so as to be detached when operated.

The torque transmission arm 10 of the present embodiment having the above configuration has
The locking pin 18 provided on the action point side portion 20 is
14 is engaged with the circumferential groove 38 of the output shaft 16 disposed in a torsional relationship in a direction perpendicular to the input shaft 12 provided on the shaft 14, and the torque transmission arm 10 swings with the repetitive forward and reverse rotation of the input shaft 12. By being moved, the output shaft 16 is reciprocated in the axial direction.

By the way, when power is transmitted from the input shaft 12 to the output shaft 16, when the locking portions 32, 32 a are in the normal state of being engaged, the power point side branch arms 26, 26 a and the operation point side branch arm 28 , 28a are coupled to each other, the rigidity of the torque transmission arm 10 is set high, and the rotation of the input shaft 12 can be reliably transmitted as the reciprocating movement of the output shaft 16.

On the other hand, when the output shaft 16 is prevented from moving by the obstacle 50 or the like as shown in FIG. 3, excessive torque acts on the torque transmission arm 10. In this case, as shown in FIG. The engaging protrusions 36, 36a are disengaged from the engaging recesses 34, 34a of the locking portions 32, 32a, and the engaging protrusions 36, 36a are formed in an arc shape of the power point side branch arms 26, 26a. By sliding the distal end portion, the force point side branch arms 26, 26a and the action point side branch arms 28, 28a
Are smoothly moved relative to each other.

As described above, after the locking portions 32, 32a are detached, torque is not transmitted through the branch arms 26, 26a and 28, 28a, and the power point side portion 14 and the action point side portion 20 The connection is made substantially only by the bending arm 24.

At this time, since the bending arm 24 is set sufficiently smaller than the allowable torque value to be transmitted in a normal state, the bending arm 24 is bent and deformed by the excessive torque, and the bending arm 24 is excessively deformed. Can absorb torque.

Therefore, it is possible to prevent the power transmission path from the input shaft 12 to the output shaft 18 from being damaged.

Since the bending arm 24 exhibits a leaf spring function, if the cause of the excessive torque is removed, the bending arm 24
Is returned to the original straight state by the action of the spring, and when the bending arm 24 is returned in this manner, the engaging projections 36, 3 of the locking portions 32, 32a are returned.
6a is locked again by the engagement recesses 34, 34a, and is automatically returned to the normal torque transmission state. In the present embodiment,
In order to prevent the bending deformation of the bending arm 24 from being excessively deformed and plastically deformed, as shown in FIG. , 26a so as to be in contact with the steps 25, 25a so that excessive bending deformation is restricted.

In the case of the present embodiment, the overlapping portion 30, 30a at the tip of the application point side branch arm 28, 28a is formed in an arc shape following the power point side branch arm 26, 26a, but the locking portion 32, The shape of the tip of the application point side branch arms 28, 28a is not necessarily arcuate, since it is only necessary to prevent interference between the portions of the application point side branch arms 28, 28a and the power point side branch arms 26, 26a when the 32a is detached. It is not limited to
It may be a straight shape or the like.

In addition, the locking portions 32, 32a precisely control the convex shapes of the engaging convex portions 36, 36a and the concave shapes of the engaging concave portions 34, 34a, so that the variation in the position when returning is minimized. can do.

By the way, in the above-described embodiment, in forming the locking portions 32, 32a, the engaging concave portions 34, 34a
Is formed, and the engagement projections 36, 36a are formed on the action point side branch arms 28, 28a.
An engaging protrusion may be formed on the arm 26, 26a, and an engaging recess may be formed on the branch arm 28, 28a on the action point side.

Further, as shown in FIG.
0a, the force point side branch arms 26 and 26a and the action point side branch arm 2
8, 28a, by forming engagement recesses 42, 42a and 44, 44a for engaging the rollers 40, 40a, respectively,
The locking portions 32, 32a can also be configured.

Further, as shown in FIG. 5, the engaging recesses 46, 46a formed in the power point side branch arm 26 are cut out continuously at the distal end side of the power point side branch arm 26, 26a, and the locking portion 32 is formed. , 32a forming radius R
By making 1 and R2 different on the left and right, the permissible torque value for interrupting the torque transmission can be changed between the forward and backward paths of the oscillating torque transmission arm 10.

In each of the embodiments described above, the power point side branch arms 26 and 26a
And the case where the action point side branch arms 28 and 28a are provided on both sides of the bending arm 24 is disclosed, but without being limited to this, the power point side branch arm and the action are provided only on one side of this bending arm 24. The same function can be exerted even when the point side branch arm is provided.

Further, as the torque transmission arm provided with the overload protection device of the present invention, in addition to the oscillating handler used in the above embodiment, for example, a positive drive device such as a roller cam or a parallel cam, or a tool The present invention can be applied to a torque wrench or the like to be used.

<< Effects of the Invention >> As described above, in the overload protection device of the present invention, the power point side portion and the action point side portion of the torque transmission arm are connected via the bending arm, and the torque action of the bending arm is performed. A locking portion is provided at the overlapping portion of the force-point side branch arm and the application point-side branch arm provided on the side in the direction, and the locking portion is configured to be detached by input of a predetermined torque or more. Excessive torque is absorbed by the bending deformation of the bending arm due to the detachment of the stopping portion, thereby preventing the power transmission path from being damaged.

Further, since the bending arm has a leaf spring function, various excellent effects can be obtained in that the torque transmission arm can automatically return to a normal torque transmission state when the overload is removed.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a torque transmission arm provided with an overload protection device according to the present invention. FIG. 2 is a configuration diagram showing an example of use of a torque transmission arm to which the present invention is applied. FIG. 4 is an explanatory view of the operation of the torque transmission arm to which the present invention is applied, FIG. 4 is a front view showing another embodiment of the present invention, and FIG. 5 is a front view showing still another embodiment of the present invention. 10 Torque transfer arm 12 Input shaft 14 Force side 16 Output shaft 20 Application point 24 Flexure arm 26,26a Power point branch arm 28,28a Application point Side branch arm 30,30a: overlapping part 32, 32a: locking part

Claims (1)

(57) [Claims] 1. A flexure arm having a leaf spring function by connecting a force point side portion and an action point side portion of a torque transmission arm, and the force point side portion and the action point on the side of the flexure arm in the torque acting direction. A power-point-side branch arm and an application-point-side branch arm that respectively protrude from the side portion; An overload protection device, comprising: an engaging portion that can be engaged and disengaged, wherein the engaging portion is disengaged when a torque equal to or more than a predetermined value acts on the torque transmission arm.