JPH06147234A - Variable torque limitter - Google Patents

Abstract

PURPOSE:To reduce power loss by switching a set torque value of a torque limitter between two stages, generating sliding in respect to a load of a specified value or more with a small torque value, and thereby preventing heat generation and reduction of life. CONSTITUTION:In a torque limitter, a cylindrical spring 4 is arranged between a first torque plate 2 and a second torque plate 3, a coil spring 5 is arranged on an outer periphery thereof, and a cylindrical body 6 is arranged further on an outer periphery thereof. The first torque plate 2, having a projection boss 2a on one side of a flange, is fixed to a rotary shaft (x). The second torque plate 3 has a recession/projection engagement surface 3a and a driving claw 3b on one side. The cylindrical spring 4 has the shape substantially the same as that of the projection boss 2a, and a cutout 4b on one side. A driving claw 5a of the coil spring 5 is engaged with a cutout 6a of the cylindrical body 6. The driving claw 3b of the second torque plate 3 is engaged with a cutout window 6b of the cylindrical body 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable torque limiter which can be used for an overload preventing mechanism of a drive unit for transmitting a rotational force and for tightening a bolt or the like with a constant torque.

[0002]

2. Description of the Related Art In general, a torque limiter is designed to protect a drive part from a rotational force above a preset torque value when an overload or an impact force is applied to the driven part in a rotary drive shaft system. It is provided at an appropriate position of the shaft system so as to cut off the transmission. The structure, strength, etc. of such a torque limiter are designed so that the maximum value of expected overload or impact force is assumed according to each application, and it can sufficiently withstand this.

In addition to the above, when the output of the drive unit exceeds the torque setting value required for tightening, such as a torque wrench for tightening bolts with a constant torque, the overload state is slid by a torque limiter. It is also used for things that keep the value constant.

[0004]

However, in the latter case, the torque setting value is set as the torque value required for tightening, so if the torque wrench is continuously driven for more than the predetermined tightening, the torque limiter will operate. Heat is generated, which shortens the service life of the torque limiter, and also causes a loss of driving force for sliding the limiter.

Therefore, in such a case, the torque limiter operates and tightens with a large set torque value for a predetermined rotation amount, but after that, it is desirable to reduce the set torque value to less than that. However, when the torque limit value is set to a certain value, the conventional torque limiter cannot be made variable thereafter.

In consideration of the problems of the conventional torque limiter, the present invention sets the initial torque limit value to a certain set value, and when a torque beyond that is set, the torque limiter is set at a constant rotation. Although it causes slippage with torque, it produces slippage with a torque smaller than the set torque after a certain number of rotations to prevent shortening of the life due to heat generation of the torque limiter, and to provide a variable torque limiter that can reduce the loss of driving force. It is an issue.

[0007]

In order to solve the above problems, the present invention provides a first torque plate having a protruding boss portion on one surface of a flange, and a second torque plate having an uneven fitting surface and a drive claw on one surface of the flange. The former is fixed to the rotary shaft at a predetermined interval with the projecting portions facing each other, the latter is rotatably attached, and a cylindrical spring having substantially the same diameter as the projecting boss portion of the first torque plate is provided between them. A coil spring is provided on the outer circumference of both the projecting boss and the cylindrical spring, and a cylindrical body is further provided on the outer diameter of the protruding boss, and one surface of the cylindrical spring is fitted to the concavo-convex fitting surface of the second torque plate. As shown in the figure, the cylindrical body has a notch on one end to engage the drive claw on the coil spring end on the same side, and a notch window on the other end to drive the second torque plate on the same side. A variable torque limiter configured to engage the claws in a loose fit It is.

[0008]

The torque limiter of the present invention configured as described above slides at the set torque value as in the conventional case when a load exceeding the set torque value is applied. Thus, for example, when tightening screws, bolts, etc. with a torque wrench, tightening is performed with a predetermined tightening torque.

In this case, when the rotational torque is input from the second torque plate, the cylindrical spring fitted in the second torque plate rotates, and the diameter of the coil spring is reduced due to the friction with the coil spring on the outer periphery to reduce the first torque. The protruding boss of the plate is tightened, whereby the rotation of the cylindrical spring is transmitted to the rotating shaft. When the load on the rotating shaft side increases and exceeds the torque limiter setting torque value, the cylindrical spring slips against the coil spring,
Torque values above the set torque value are not transmitted.

In this state, when the second torque plate rotates by a certain angle, the driving pawl of the second torque plate hits the notch window of the cylindrical body to rotate the cylindrical body, and the driving pawl of the coil spring engaged with this is forced. The coil spring is rotated in the opening direction by rotating the coil spring. Therefore, the set value of the slip torque is reduced.

On the contrary, when transmitting the rotational torque from the first torque plate to the second torque plate, if the rotary shaft is rotated in the opposite direction to the above, the torque is transmitted by the same action as described above, and the torque set value is set. Functions as a torque limiter that changes in two steps.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main sectional view of a variable torque limiter of an embodiment, and FIG. 2 is an exploded perspective view thereof. The variable torque limiter 1 is provided with a first torque plate 2 and a second torque plate 3 which are opposed to each other, a cylindrical spring 4 is provided between them, a coil spring 5 is wound around the outer periphery thereof, and a cylinder is further provided on the outer periphery thereof. The body 6 is formed by stacking it.

As shown in FIG. 2, the first torque plate 2 has a protruding boss 2a on one side of the flange and is fixed to the rotary shaft x. The second torque plate 3 has a concave-convex fitting surface 3a and a drive claw 3b on one surface of the flange, and is rotatable about the rotation axis x. The first torque plate 2 and the second torque plate 3 are provided such that their respective protrusions face each other. The concavo-convex fitting surface 3a of the second torque plate 3 is formed such that opposing ¼ circles are concave and convex.

The outer diameter of the cylindrical spring 4 is substantially the same as that of the protruding boss 2a of the first torque plate 2, and the cylindrical spring 4 is separated at 4a along the length direction at an arbitrary position on the cylinder, and one end thereof is a notch 4b. It has uneven edges. The notch 4b has a shape that fits into the concave-convex fitting surface 3a of the second torque plate 3, and the opposing 1/4 circle is notched.

The coil spring 5 is wound around the outer periphery of both the cylindrical spring 4 and the protruding boss 2a of the first torque plate 2, the drive pawl 5a is provided at one end, and the other end is of a predetermined length. It has been disconnected.

The cylindrical body 6 is provided with a notch 6a at one end and a notch window 6b at the other end. When assembled, the drive pawl 5a of the coil spring 5 and the drive pawl of the second torque plate 3 are respectively provided. Three
b is engaged. As shown in FIG. 2, by providing grease reservoirs 2b at several places on the sliding surface of the protruding portion of the first torque plate, the life during idling can be increased.

The torque limiter of the embodiment constructed as described above operates as follows. (1) First, a case where the rotational torque is input from the second torque plate 3 and the shaft x is driven via the first torque plate 2 will be described with reference to FIG.

(A) When the rotational torque is input from the second torque plate 3, the rotational torque is transmitted to the cylindrical spring 4. At this time, the rotation direction of the cylindrical spring 4 is set to the direction in which the coil spring 5 contracts as shown in the drawing. When the coil spring 5 contracts, the cylindrical spring 4 is tightened, a radial force is generated between the cylindrical spring 4 and the coil spring 5 to generate a brake torque, and the rotational torque input from the second torque plate 3 becomes the first torque plate. 2 is transmitted.

(B) During the above rotation, a braking force is generated on the shaft, and when the braking force is greater than the braking torque generated between the cylindrical spring 4 and the coil spring 5, the cylindrical spring 4 and the coil spring 5 are connected. Slippage occurs and the first torque plate 2
The rotation torque is not transmitted to.

(C) When slippage occurs between the cylindrical spring 4 and the coil spring 5, the drive pawl 3 of the second torque plate 3
b hits the drive claw notch window 6b of the cylindrical body 6, rotates the cylindrical body 6, and the cylindrical body 6 drives the drive claw 5a of the coil spring 5.
Thus, the coil spring 5 is rotated in the opening direction. (Torque transmission: second torque plate 3 → cylindrical spring 4 → cylindrical body 6
→ Coil spring 5) (d) Since the coil spring 5 is rotated by the cylindrical body 6 in the direction in which the coil spring 5 opens, a brake torque is generated between the cylindrical spring 4 and the coil spring 5 in the state of (b). However, since the action of opening the spring occurs in this state, the rotational torque becomes small.

(Torque transmission: second torque plate 3 → cylindrical spring 4 → cylindrical body 6 → coil spring 5, slip between inner diameter of coil spring 5 and outer diameter of first torque plate 2) The value of the set torque transmitted from the torque plate to the rotating shaft is, as shown in FIG. 4, the maximum set torque at first, corresponding to (a) of FIG. 3, but decreased to a certain value after a constant rotation. It becomes the set torque.

(2) Contrary to the case of (1), the case where the rotational torque is input from the first torque plate 2 and the torque is transmitted to the second torque plate will be described with reference to FIG. (A) When torque is transmitted from the first torque plate 2 within the set torque of the limiter, the torque transmission path is the first torque plate 2
→ coil spring 5 → cylindrical spring 4 → second torque plate 3.
Torque is transmitted through the torque transmission path. The rotation direction is opposite to the case of (1) as shown.

(B) When a load is generated on the second torque plate 3 and a large torque is generated, the second torque plate 3 stops, and torque transmission at this time is transmitted from the first torque plate 2 → the coil spring 5 → the cylindrical body 6 However, a slip occurs between the coil spring 5 and the cylindrical spring 4, and the slip torque is transmitted at the maximum set torque of the limiter.

(C) As described above, the torque is transmitted to the first torque plate 2 → the coil spring 5 → the cylindrical body 6, but this torque causes a slip between the coil spring 5 and the cylindrical spring 4, so that the coil spring is formed. When 5 rotates, cylindrical body 6 rotates,
It hits the drive claw 3b of the second torque plate 3 which is stopped in the cutout window 6b.

(D) In this way, when the cylindrical body 6 hits the drive pawl 3b within the cutout window 6b while sliding between the coil spring 5 and the cylindrical spring 4 as described above, the rotation of the coil spring 5 is stopped. During that time, the coil spring 5 is loosened by the amount of movement in the cutout window 6b. For the subsequent rotation, the coil spring 5 is prevented from rotating by the second torque plate 3, so that between the first torque plate and the half portion of the coil spring 5 engaged with the first torque plate 2. Start slipping. At this time, since the coil spring 5 is stopped, the first torque plate 2 rotates in a state of idling with respect to the loosened coil spring, and the idling torque becomes small. Therefore, also in this case, the transmission torque becomes small.

[0026]

As described in detail above, the torque limiter of the present invention is provided with a cylindrical spring, a coil spring, and a cylindrical body so as to sequentially overlap each other between the first torque plate and the second torque plate. Since the set torque can be changed by engagement, it is possible to change the set torque after the constant rotation to the set torque or less. Therefore, the driving force of the device can be reduced, and the set torque can be reduced. Since the torque generation part that has changed from the set torque changes, compared with the one that has been generated in a fixed part in the past,
The set torque can be expected to have a long life, and various advantages such as changing the length of the set torque generated by changing the angle of the window for the second torque plate ring driving claw of the ring can be obtained.

[Brief description of drawings]

FIG. 1 is a main sectional view of a torque limiter according to an embodiment.

FIG. 2 is an exploded perspective view of the above.

FIG. 3 is a diagram for explaining a torque transmission method.

FIG. 4 is a torque curve change diagram.

5 is an explanatory diagram of a torque transmission method in the opposite direction to FIG.

[Explanation of symbols]

 1 Torque Limiter 2 First Torque Plate 2a Projection Boss 3 Second Torque Plate 3a Concavo-convex Fitting Surface 3b Drive Claw 4 Cylindrical Spring 4a Separation Part 4b Concavo-convex Part 5 Coil Spring 5a Drive Claw 6 Cylindrical 6a Notch 6b Notch Window

Claims (1)

[Claims] 1. A first torque plate having a protruding boss portion on one surface of a flange and a second torque plate having a concave-convex fitting surface and a drive claw on one surface of the flange, with their respective protruding portions facing each other and being mounted on a rotary shaft at predetermined intervals. On the other hand, the former is fixed, the latter is rotatably mounted, and a cylindrical spring having the same diameter as the protruding boss portion of the first torque plate is provided between the two, and the outer circumference of both the protruding boss portion and the cylindrical spring is provided. A coil spring and a cylindrical body on the outer diameter of the coil spring are overlapped with each other, and one side of the cylindrical spring has an uneven shape so as to fit with the uneven fitting surface of the second torque plate. Is provided to engage the drive pawl at the same side of the coil spring, and a cutout window is provided at the other end so that the drive pawl is loosely engaged with the second torque plate on the same side. Variable torque limiter consisting of.