JPH073254B2 - Manual return overload clutch - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called overload clutch for preventing torque transmission when an overload is applied to a driven portion, and more particularly to a torque cutoff during overload. The latter relates to an overload clutch that keeps the torque transmission cut off unless it is intentionally manually returned.

Conventional technology and its problems Conventionally, it is provided between a drive section and a driven section of a torque transmission mechanism, and when the load torque exceeds a predetermined value (this is called "trip torque"), the drive torque is released. There is an overload clutch such as a ball clutch or a roller clutch as a kind of safety device for preventing damage to the driving side mechanism and the driven side mechanism.

One of the overload clutches is an electromagnetic type. An electromagnetic overload clutch has a torque transmission element arranged in a recess formed on both the driving side and the driven side, and the trip torque between the driving side and the driven side is adjusted by a magnet and a leaf spring. Is.

However, since the trip torque is adjusted electrically, the problem that electrical noise generated from the overload clutch adversely affects peripheral devices, and the noise and vibration that the leaf spring flaps when the overload clutch operates There's a problem.

In addition, in order to avoid the problem caused by the continuous overload condition for a long time, that is, the problem of wear and heat generation due to repeated repeated collisions between the torque transmission element and the recess, a manual reset is performed. There is a need for a formula overload clutch.

In order to solve the above-mentioned problems, an object of the present invention is to make it possible to mechanically adjust the trip torque of an overload clutch, and yet still be able to perform a manual return in response to recent demands. To provide a mechanical overload clutch.

Means for Solving the Problems The present invention holds a torque transmission element by a torque transmission element holding penetrating portion formed on one of a hub or a driven plate, and a torque transmission element formed on the other of the hub or the driven plate by a pressure plate. In the overload clutch, the torque transmission element is pressed against the holding bottom portion by a spring to transmit torque, and the torque transmission element escapes from the torque transmission element holding bottom portion against the pressing when the torque transmission element is overloaded. An inclined portion that presses the torque transmission element in a direction intersecting with the rotation center axis of the overload clutch is formed in a portion of the pressure plate that contacts with the torque transmission element, and the torque transmission element holding penetrating portion has a shape of V when viewed from the axial direction. The pressure transmitting element holding bottom portion is a V-shaped groove, Taper surfaces are provided at the corners of the inner peripheral portion of the spring plate on the spring side, and the balls are arranged so as to contact the outer peripheral cylindrical surface of the hub and the tapered surface and to be pushed in the axial direction by the springs. An annular groove is provided on the outer peripheral cylindrical surface of the hub on the spring side from the position of the ball at the time of torque transmission, and the ball falls into the annular groove at the time of torque cutoff. The above problem is solved by an overload clutch in which force does not act on the pressure plate.

In the operating torque transmission state, the torque transmission element receives a pressing force from the spring via the ring and the ball and is engaged with the bottom portion of the torque transmission element holding portion. Due to this pressing force, the torque transmission element is pushed into the V-shaped portion of the torque transmission element holding penetrating portion and the V-shaped groove of the bottom portion of the torque transmission element holding bottom, and is supported in two-point contact with each V-shaped portion. ing. Therefore, the torque transmission element is not contacted loosely with the V-shaped portion of the torque transmission element holding through portion by the inclined portion and is always pressed in contact with two points, so that backlash does not occur.

When a torque equal to or greater than a predetermined value is generated between the hub and the driven plate, the torque transmission element presses the pressure plate and compresses the spring via the ball and the ring. The pressure plate, the ball and the ring move in the axial direction by the escape operation of the torque transmission element. Here, an annular groove is provided on the outer periphery of the hub, and a ball that receives a component force in the axial direction from the tapered surface of the pressure plate is liable to come into contact with the annular groove during the axial movement of the torque transmission element. Fall into the annular groove.

At this time, the pressing force in the axial direction does not act on the pressure plate. That is, the pressing force of the spring acts on the annular ring and the ball, but exerts only a radially outward force from the ball to the pressure plate. This is because the ball retreats from the movement trajectory of the pressure plate. Therefore, the force that opposes the movement of the torque transmission element to completely escape from the bottom portion holding the torque transmission element is eliminated, and the pressure plate can further move in the axial direction. The axial pressing force from the ball is absorbed by the annular groove. Thus, once the overload is applied, the torque cutoff state is maintained.

The return to the torque transmission state is performed by aligning the phases of the torque transmission element and the bottom portion holding the torque transmission element, and manually moving the pressure plate in the axial direction. The shape of the annular groove is such that the ball can escape from it by the pressing force of the spring, and there are, for example, a V-shape and a depth that is shallower than the radius of the ball. Therefore, when the pressure plate returns to its original position, the ball receives a force outward in the radial direction from the annular groove, escapes from the annular groove, and again contacts the tapered surface of the pressure plate,
The pressing force of the spring is transmitted in the axial direction. In this way, the torque transmission state can be restored.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings by taking a ball clutch as an example.

The overload clutch 10 of the first embodiment of the present invention has a hub 20 and a driven plate 40, as shown in FIG.

As shown in FIG. 2, the driven plate 40 has a V-shaped notch (torque transmission element holding penetrating portion) that widens toward the inner periphery.
A plurality of 41 are radially formed at unequal intervals. The reason for unequal spacing is that the number of mesh points per rotation is 1
This is to limit the number of places. It is of course possible to arrange the plurality of notches at equal intervals to form an overload clutch capable of engaging at a plurality of points. Each notch
In the valley portion 42 of 41, a ball (steel ball) that is a torque transmission element
12 is pushed in by the configuration described later.

This driven plate 40 has coupling flanges 13,1
It has a screw hole 43 for fixing to 4. The coupling flanges 13 and 14 are attached to one shaft B by a cylindrical portion. Reference numeral 15 is a known device for fastening the coupling flange 14 to the shaft B, which includes a pressure flange 16 and a bolt 17.
Thus, the coupling flange 14 and the shaft B are fastened by utilizing the wedge action of the taper ring.

The hub 20 has a collar 22 formed at one end of a tubular portion 21, a threaded portion 23 on the outer periphery, a diameter expanded portion 24 on the inner periphery, and a screw hole 25 on the end face at the other end. Fastening device 18 inside the enlarged portion 24
Is the same as that shown by the above-mentioned reference numeral 15, and the hub 20 and the shaft A are fastened by the pressure flange 19 and the bolt 17.

As shown in FIGS. 3 and 4, V-shaped elongated grooves (torque transmission element holding bottom portion) 26 that are unequal in the circumferential direction are radially provided on the inner surface of the collar 22. The V-shaped long groove 26 has the same phase as the notch 41 described above. V-shaped long groove in tsuba 22
A flat portion 27 is formed between the 26.

Returning to FIG. 1, a pressure plate 30 is loosely fitted in the tubular portion 21 of the hub 20 with a gap in the inner circumference. The surface of the pressure plate 30 that faces the flange 22 is an inclined portion 31 that forms a conical surface in a portion that is sloped so as to face the valley portion 42 of the notch 41 of the driven plate 40. The inclined portion 31 is a torque transmission element formed by a coil spring 32 described later.
It has a function of pressing 12 to the valley portion 42 and the bottom portion 28 of the V-shaped groove 26.

An adjusting nut 33 is screwed onto the threaded portion 23 at the other end of the hub 20. Between the adjusting nut 33 and the pressure plate 30,
A plurality of coil springs 32, a ball retaining ring 36 and a ball 37
Is provided. The adjusting nut 33 adjusts the force with which the pressure plate 30 presses the torque transmission element 12. After adjustment, set screw 34 on adjustment nut 33
Screw the lock plug 35 at the end of the
To prevent it from loosening. The coil spring 32 presses the pressure plate 30 with each biasing force.

The thickness of the torque transmission element holding portion of the driven plate 40 is thinner than the diameter of the torque transmission element 12, and in the stationary state,
Between the pressure plate 30 and the collar 22, they are arranged with a gap therebetween. The pressing force from the pressure plate 30 presses the torque transmission element 12 in the direction of the valley 42 of the notch 41 of the driven plate 40 and in the direction of the bottom 28 of the V-shaped long groove 26 by its inclined portion 31 and makes two-point contact with each. Let

Due to this pressing force, the driven plate 40 is positioned in the radial direction with respect to the pressure plate 30, and the hub 20
Has emerged from. The axial movement is free by the gap. The pressure plate 30 is also a hub.
It has risen from 20. However, even in the floating state, backlash does not occur because the torque transmission element 12 contacts the notch 41 of the driven plate 40 and the V-shaped long groove 26 of the collar 22 at two points each. Therefore, the hub 2
0, even if there is a gap error when mounting the driven plate 40 and the coupling flanges 13 and 14 on the axis B, the driven plate 40 is allowed to move relative to the hub 20 in the axial direction. Further, even if there is an angular error between the axis A and the axis B, the driven plate 40 can be tilted to absorb the error.

Further, as shown in FIG. 5, a tapered surface 51 is formed on the right side surface (ball 37 side) 50 of the pressure plate 30. The ball retaining ring 36 has a through hole 38 for retaining the ball 37. The through hole 38 has a perfect cylindrical shape. The right side surface of the ball holding ring 36 receives the biasing force of the coil spring 32, and the left side surface accurately presses the ball 37 in the axial direction. The inner diameter of the ball retaining ring 36 is a diameter slidable with the outer peripheral cylindrical surface 60 of the hub 20. Ball retaining ring
The ball 37 held by the 36 acts as a bearing when the adjusting nut 33 is tightened, so that the adjusting nut 33 can be smoothly tightened, and it is necessary to incorporate a thrust bearing, etc., which was necessary in the past. do not do.

The ball 37 has a diameter d (FIG. 6) larger than the distance t between the outer peripheral cylindrical surface 60 of the hub 20 and the inner peripheral surface 52 of the pressure plate 30, and in the torque transmitting state, the outer peripheral cylindrical surface 6 of the hub 20.
0, the tapered surface 51 of the pressure plate 30 and the through hole 38 of the ball holding ring 36 are sandwiched. ball
The force acting on 37 is the axial pressing force P1 from the coil spring 32 via the ball retaining ring 36, and the pressure plate.
The reaction force P2 from the tapered surface 51 of 30 and the reaction force P3 from the outer peripheral cylindrical surface 60 of the hub 20 are balanced. It should be noted that P4 and P5 are forces obtained by decomposing the reaction force from the tapered surface 51 of the pressure plate 30 to the ball 37 into an axial component force and a radial component force. Therefore, P1 = P4: P3 = P5. Thus, all the pressing force of the coil spring 32 acts as a force for engaging the torque transmission element 12 with the V-shaped elongated groove 26. In this way, the balls 37 are attached to the outer peripheral cylindrical surface 60 of the hub 20.
Therefore, the overload clutch 10 suitable for downsizing the spring 32 can be obtained.

A V-shaped annular groove 61 is formed on the outer peripheral cylindrical surface 60 of the hub 20. The annular groove 61 is used for the ball 37 in the torque transmitting state.
Has a starting point 62 on the spring side by A from the contact point between the outer peripheral cylindrical surface 60 of the hub 20 and This dimension A corresponds to
Is shorter than the amount of movement when it escapes from the V-shaped groove 26, and the ball 37 reaches the starting point 62 of the annular groove 61 before the torque transmission element 12 completely escapes from the V-shaped groove 26.

When no overload is applied during torque transmission rotation, the torque transmission element 12 is pressed by the pressure plate 30 so that the torque transmission element 12 and the V-shaped notch 41 of the driven plate 40 and two points, and the V-shaped long groove 26 of the collar 22 of the hub 20. Since each of them is in contact with two points and settles down, both shafts A and B rotate integrally and torque is transmitted. Even if an angular error or a spacing error occurs during rotation, the overload clutch 10 itself can absorb these errors, as described above. Of course, no backlash occurs.

Next, when the driven plate 40 is overloaded, the shaft A continues to rotate despite the rotation of the driven plate 40 being blocked, so that the torque transmission element 1 tries to escape from the V-shaped long groove 26. When the torque transmission element 12 pushes the pressure plate 30 rightward against the pressing force of the coil spring 32, the ball 37 approaches the annular groove 61. Since the distance to the annular groove 61 is shorter than the movement amount of the torque transmitting element 12, before the torque transmitting element 12 completely escapes from the V-shaped long groove transmission 26, as shown in FIG. Approaching the starting point 62 of 61. This behavior is caused by P4> P1.

FIG. 7 shows the torque transmission element 12 and the pressure plate.
It is a figure which shows immediately after the movement amount of 30 exceeds A. At this time, if the angle of the tapered surface 51 of the pressure plate 30 is 45 °, then P5> 0, and the ball 37 receives a force in the direction of falling into the annular groove 61. Therefore, at the moment when the amount of movement of the torque transmission element 12 exceeds the dimension A, the ball 37 falls into the annular groove 61.

FIG. 8 shows a state in which the ball 37 has fallen into the annular groove 61 and has retreated from the movement trajectory of the pressure plate 30. The ball 37 is at the center position just before it falls into the annular groove 61 (Fig. 6).
It is in a state of being moved from the position B by the axial direction and by the size d-t by the radial direction. The ball 37 is then held by the ball retaining ring 36.
At three points, the through hole 38, the inner peripheral surface 52 of the pressure plate 30 and the groove surface 63 of the annular groove 61 make three-point contact, and the pressing force of the coil spring 32 does not act to press the pressure plate 30 to the left. That is, the pressing force P1 of the coil spring 32, the reaction force P6 from the inner peripheral surface 52 of the pressure plate 30 and the annular groove
The reaction force P7 from the groove surface 63 of 61 is balanced, and the pressing force of the coil spring 32 is canceled by the axial component force from the groove surface 62 of the annular groove 61. Therefore, once the balls 37 fall into the annular groove 61, the axial pressing force no longer acts on the pressure plate 30.

Here, the dimension A, the dimension B, the dimension C (the axial dimension from the center of the ball 37 to the end portion on the inner peripheral surface side of the tapered surface 51) and the moving amount of the torque transmission element 12 (L) are as follows. Set to meet.

A + B + C ≦ L When A + B + C exceeds L, when the torque transmission element 12 has completely escaped from the V-shaped long groove 26, the ball 37 is not yet completely retracted from the movement track of the pressure plate 30, so that the overload is not caused. This is because, when is released, the pressing force of the coil spring 32 acts on the pressure plate 30 and the torque transmission element 12 automatically returns to the V-shaped long groove 26.

When A + B + C = L, the ball 37 is located at a position where it interferes with the edge of the tapered surface 51 of the pressure plate 30. Therefore, it is desirable that A + B + C <L in order to ensure the torque cutoff state. The allowance for that purpose is indicated by reference sign D in FIG.

As described above, when the driven portion is overloaded, the torque is cut off by the balls 37 rolling on the outer peripheral cylindrical surface 60 of the hub 20,
It occurs at the moment when it reaches the starting point 62 of the annular groove 61. The pressing force of the coil spring 32 acting on the torque transmitting element 12 is transmitted in the axial direction by 100% (theoretical value ignoring friction loss and the like). Since the distance from the contact point between the ball 37 and the outer peripheral cylindrical surface 60 of the hub 20 to the starting point 62 of the annular groove 61 in the torque transmitting state is a straight line, the setting is easy.

In order to return from the torque cutoff state to the torque transmission state, first, the phases of the torque transmission element 12 and the V-shaped long groove 26 are aligned, and the pressure plate 30 is moved leftward in FIG. The ball 37 has an annular groove 61 due to the pressing force of the coil spring 32.
The ball 37 automatically escapes from the annular groove 61 because it receives a force radially outward from the groove surface 63. In this way, the ball 37 is again attached to the tapered surface of the pressure plate 30.
Touching 51, torque transmission is restored.

FIG. 9 shows a second embodiment of the present invention. That is,
Like the overload clutch disclosed in Japanese Patent Application No. 1-43136 by the same applicant, a V-shaped notch 141 that expands outward is provided on the hub 120 side, and a V formed on the driven side.
The torque transmission element 112 is arranged in the long groove 126, and the pressure transmission force is applied to the torque transmission element 112 in the direction of the V-shaped long groove 126 by the pressure plate 130 to transmit the torque, and the ball is held between the pressure plate 130 and the coil spring 132. ring
There is also one in which 136 and a ball 137 are arranged so that the ball 137 is fitted into an annular groove 161 formed on the outer peripheral cylindrical surface of the hub 120 when overloaded.

The above describes the preferred embodiments of the present invention, and should not be limited thereto. Therefore, the following modifications are also included in the present invention.

First, the shape of the annular groove is not limited to the V shape as shown in FIGS. 5 to 8, but may be formed so that the planes perpendicular to the axis face each other. Further, one may be perpendicular to the axis and the other may be inclined like a V shape.

Secondly, unlike the case of arranging the V-shaped notch and the V-shaped long groove in the axial direction as in the above-mentioned embodiment, Japanese Patent Publication No. 55-21
It may be configured to be arranged in the radial direction, such as No. 894.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects.

(1) At the time of torque transmission, the torque transmission element is not loosely fitted in the torque transmission element holding bottom portion and is always in contact with two points. Therefore, the position of the torque transmission element with respect to the torque transmission element holding penetrating portion is always constant. Therefore, the relative position of the driven plate of the hub does not shift. In addition, re-engagement is sure.

(2) The trip torque can be set mechanically, and electrical noise that adversely affects peripheral devices is not generated.

(3) Since the balls are brought into contact with the tapered surface of the pressure plate and the outer peripheral cylindrical surface of the hub, the spring force is almost 100% transmitted to the torque transmission element and is transmitted through the plurality of tapered surfaces. The trip torque can be managed more accurately and the spring can be made smaller and lighter than the one.

(4) Since the torque is cut off when the ball rolls on the outer peripheral cylindrical surface of the hub and reaches the starting point of the annular groove, the contact point between the ball and the hub in the torque transmitting state and the starting point of the annular groove from this contact point. The trip torque can be set with the axial distance of up to as a requirement. In this case, it is possible to accurately and easily manage the trip torque simply by managing the linear interval, and the trip torque management becomes easier than in the conventional overload clutch including a plurality of tapered surfaces.

(5) Further, since the annular groove is provided on the outer peripheral cylindrical surface of the hub, the number of parts can be reduced and the tapered surface does not need to be processed accurately, so that the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an axial sectional view of an overload clutch according to a first embodiment of the present invention in a torque transmitting state, FIG. 2 is a front view of a driven plate, FIG. 3 is a front view of a hub, and FIG. The upper surface of the drawing, FIGS. 5 to 8 are partially enlarged sectional views of FIG. 1 for explaining the operation when the torque transmission state is changed to the torque cutoff state, and FIG. 9 is a second embodiment of the present invention. FIG. 6 is an axial sectional view of the overload clutch in a torque transmission state. 10 …… Overload clutch 12,112 …… Torque transmission element 20,120 …… Hub 22 …… Trim 26,126 …… V-shaped slot (bottom portion with torque transmission element holding) 27 …… Flat portion, 28 …… Bottom portion 30,130 …… Pressure plate 31 …… Inclined part 32,132 …… Coil spring 36,136 …… Ball 37,137 …… Ball holding ring 40 …… Driven plate 41,141 …… V-shaped notch (torque transmission element holding penetration part) 42 …… Valley part, 51 …… taper Surface 52 …… Inner peripheral surface, 60 …… Outer peripheral cylindrical surface 61,161 …… Annular groove

Claims (1)

[Claims] 1. A torque transmission element holding penetrating portion formed on one of a hub and a driven plate holds a torque transmission element, and a spring is provided on a bottom portion of a torque transmission element holding formed on the other of the hub and the driven plate by a pressure plate. In the overload clutch, which presses to transmit torque, and when the torque is transmitted, the torque transmission element comes out from the bottom portion holding the torque transmission element against the pressure, the pressure plate contacting the torque transmission element. An inclined portion for pressing the torque transmission element in a direction intersecting with the rotation center axis of the overload clutch is formed in the portion of the torque transmission element holding through portion, and the torque transmission element holding penetrating portion has a V-shape when viewed from the axial direction. The transmission element holding bottom portion is a V-shaped groove, and A tapered surface is provided at a corner portion of the side inner peripheral portion, and a ball is in contact with an outer peripheral cylindrical surface of the hub and the tapered surface, and is in contact with a ring end surface arranged so as to be axially pushed by the spring. And an annular groove is provided on the outer peripheral cylindrical surface of the hub on the spring side from the position of the ball during torque transmission, and when the torque is shut off, the ball falls into the annular groove, so that the spring force increases the pressure. An overload clutch characterized by not acting on the plate.