JPH061085B2 - 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.

Conventional technology and its problems Conventionally, it is provided between the drive unit and the driven unit of the torque transmission mechanism, and when the load torque exceeds a predetermined value, the drive torque is released, and the drive-side and driven-side mechanisms are damaged. As a kind of safety device to prevent, there is an overload clutch such as a ball clutch and a roller clutch.

The structure is such that the torque transmission element is held by the torque transmission element holding penetrating portion formed on one of the hub and the driven plate, and the pressure plate presses the bottom portion of the torque transmission element holding formed on the other of the hub and the driven plate to apply torque. Transmission is performed, and torque transmission is interrupted by causing the torque transmission element to escape from the bottom portion having the torque transmission element holding portion against the pressing force at the time of overload.

Therefore, at the time of the escape, the torque transmission element holding through portion is shaped to have an outer shape such that the torque transmission element penetrates through the torque transmission element holding through portion so that the torque transmission element can be held and moved in the torque transmission element holding through portion (for example, of a ball). In the case of a circle, and in the case of a roller, a square hole was provided, and a certain gap was provided between them.

Therefore, the torque transmission element is held in a so-called loosely fitted state within the torque transmission element holding penetrating portion.

However, with such a configuration, when the rotation direction of the drive side of the overload clutch changes, the gap becomes backlash, the relative position of the hub and the driven plate is deviated, and the position between the drive side and the driven side is changed. There was a problem that deviation occurred.

Further, even if the rotation direction is constant, there is a problem that the position of reengagement of the torque transmission element with respect to the bottom portion holding the torque transmission element is not determined after the overload is eliminated.

Further, in order to reduce the influence of the gap, if the processing precision is increased by performing strain removal after the heat treatment in order to reduce the gap, there is a problem that the processing is time-consuming and costly. .

Therefore, in view of the above problems, the applicant has already proposed Japanese Patent Application No.
No. 262764, we have applied for an invention relating to overload chilatch that eliminates backlash. In the overload clutch as described above, the configuration forms an inclined portion that presses the torque transmission element in a direction intersecting the rotation center axis of the overload clutch in the portion of the pressure plate that contacts the torque transmission element. The torque transmission element holding penetrating portion is an overload clutch having a V-shape when viewed from the axial direction, and the torque transmission element holding bottom portion is a V-shaped groove.

In the overload clutch, a component force generated by pressing the torque transmission element by the inclined portion causes the torque transmission element to transmit the torque, and the V-shaped portion of the torque transmission element holding penetration portion and the torque transmission element holding bottom portion. Is pressed into the V-shaped groove of the V-shaped groove and is supported by two points in contact with each V-shaped portion. At the time of overload, the V-shaped groove of the bottom portion with the torque transmission element holding is resisted against the pressing force of the inclined portion. Escape and move to the flat part of the driven plate to release the overload.

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 in contact with and pressed by two points, so that backlash does not occur.

However, even when overloaded, the ball is pinched between the driving side and the driven side and contacts the V-shaped part at two points, so rolling is prevented and the ball makes sliding contact in the V-shaped part. Alternatively, the sliding contact with the driven plate causes the friction to transmit a so-called "twitching torque" to the driven side even when the overload is cut off.

Therefore, when the set torque for overload is low, the driven side rotates together, which makes it difficult to re-engage, and when used for a long time in such a condition, seizure or wear may occur due to friction. There is a problem of doing.

Means for Solving the Problems The present invention provides an overload clutch in which the above-mentioned backlash is eliminated, in a two-point contact state with a torque transmission element holding penetration portion in a flat portion between the torque transmission element holding bottom portions. The above problem is solved by a configuration in which an inclined step portion having an angle larger than the inclination angle of the inclined portion of the pressure plate is provided on the valley side of the torque transmission element holding through portion with respect to the pitch circle of the torque transmission element.

During operation torque transmission, the torque transmission element is held between the bottom portion of the torque transmission element holding portion and the pressure plate, and rotational torque is transmitted from the hub to the driven plate.

At the time of overload, the torque transmission element rides on the flat portion from the bottom portion with the torque transmission element holding. The torque transmission element receives a component force in the direction away from the two-point contact of the torque transmission element holding penetrating portion from the inclined step portion provided in the flat portion. As a result, the torque transmission element is held by the pressure plate, the flat portion and the inclined step portion, and is held without making two-point contact with the torque transmission element holding penetration portion.

Therefore, the torque transmission element can freely roll.

As described above, the rolling contact facilitates the alignment for re-engagement.

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

As shown in FIG. 1, the hub 10 has a flange 13 formed at the center of a tubular portion 11, and a set screw 12 for rotating in cooperation with the shaft A is projected on the inner peripheral surface thereof. .

As shown in FIG. 2, a plurality of V-shaped notches (torque transmission element holding penetrating portions) 14 that spread toward the outer periphery are radially formed in the collar 13 at unequal intervals. The reason for unequal spacing is to limit the meshing point in one rotation to one place.) The valley portion 14a of each notch 14
A ball (steel ball) 15 which is a torque transmission element is pushed into this by a configuration described later.

Referring back to FIG. 1, a disk-shaped driven plate 17 is provided on the cylindrical portion 11 on the left side of the collar 13 so as to rotate with a radial bearing 16 interposed.

The right side surface 1 of the driven plate 17 facing the brim 13
As shown in FIG. 3 to FIG.
A plurality of ball-holding bottom portions 18, which are V-shaped grooves in which 5 is inserted, are radially cut at the same position facing the notch 14. A flat portion 19 is formed between the cutouts 14. An inclined stepped portion 19a is formed on the flat portion 19. The inclined step portion 19a has a starting point at a diameter D2 smaller than the diameter D1 of the engagement pitch circle of the ball, and is inclined toward the ball holding bottom portion 18 side and is continuous with the flat portion 19. The diameter D1 is a diameter that intersects the center of the ball 15 in a state where the ball 15 is in two-point contact with the notch 14. The inclination direction is the same as the inclination direction of the pressure plate 30 described later. The inclination angle φ of the inclined step portion 19a is larger than the inclination angle θ (Fig. 1) of the pressure plate. The edge 19c of the inclined surface 19b is flush with the ball holding bottom portion 18 so that the ball 15 can smoothly ride on the inclined surface 19b when the overload is cut off. A thrust bearing 20 is interposed between the right side surface 17a and the collar 13.

A screw 21 is formed on the left end of the cylindrical portion 11 of the hub 10, and a fixing nut 22 is screwed into the screw 21. Fixing nut 22
Is for holding the driven plate 17 in close contact with the pressure plate 30 with the thrust bearing 20 interposed therebetween. The set screw 23 provided on the fixed nut 22 presses the lock plug 24 against the screw 21 at the tip thereof to prevent the fixed nut 22 from loosening.
A thrust bearing 25 is interposed between the fixed nut 22 and the driven plate 17.

A pressure plate 30 is loosely fitted in the tubular portion 11 on the right side of the collar 13 of the hub 10. Pressure plate 3
Near the outer periphery of the surface 30a where 0 faces the collar 13, an inclined portion 31 formed of a conical surface having a downward slope toward the axis A is formed. The inclined portion 31 is formed by cutting the ball 15 with a coil spring 34, which will be described later, and the valley portion 14a of the notch 14 and the ball holding bottom portion 1.
8 is pressed.

A screw 32 is formed on the right end of the hub 10, and an adjusting nut 33 is screwed into the screw 32.

The adjusting nut 33 adjusts the force with which the pressure plate 30 presses the ball 15 by interposing a plurality of coil springs 34 and thrust bearings 35 with the pressure plate 30, and the lock plug at the tip of the set screw 36. 37 is pressed and engaged with the screw 32 to prevent loosening.

Next, the operation will be described with the axis A as the driving side and the driven plate 17 as the driven side.

First, when no overload is applied, that is, when meshing,
The ball 15 is notched by the component force P (FIG. 1) parallel to the axis A among the component forces generated by the pressing of the inclined portion 31 to the ball holding bottom portion 18 and by the component force F perpendicular to the axis A. 14
Are simultaneously pressed by the valley portions 14a of the hub 10, and the valley portions 14a of the hub 10 and 2 points, the ball holding bottom portion 18 and 2 points of the driven plate 17, and the inclined portion 31 and 1 point of the pressure plate 30 at a total of 5 points. It is supported. Therefore,
Since the ball 15 is pressed and settled by the ball holding bottom portion 18 which is a V-shaped groove, the entire ball clutch rotates integrally, and the rotation torque of the shaft A is connected to the driven plate 17 ( (Not shown).

Next, when the driven plate 17 is overloaded, the shaft A continues to rotate despite the rotation of the driven plate 17 being blocked, so that the ball 15 resists the component force P and the valley 14a. Using the inside as a guide, it moves to the right in FIG. 1, escapes from the ball holding bottom portion 18, and transfers to the flat portion 19. This transfer occurs when the ball 15 rides on the boundary 18a (FIG. 5) of the flat portion 19 from the ball-holding specific bottom portion 18 and moves axially by the length L shown in FIG. When the ball 15 rides on the flat portion 19, it hits the edge 19c of the inclined stepped portion 19a and is guided by this portion and rides on the inclined surface 19b. D3 indicates the pitch circle diameter of the ball 15 after transfer.

In this way, the ball 15 has the inclined surface 19b of the stepped portion 19a.
Get on. At this time, since the inclination angle φ of the inclined surface 19b is larger than the inclination angle θ of the fresher plate 30, the ball 15 receives a component force outward in the radial direction and moves in the same direction as indicated by H in FIG. . And the ball 15
Pressure plate 30, flat portion 18, inclined step portion 19
It is supported by a.

7 and 8 show the amount of displacement of the ball 15, the ball 15 and the notch 1 when the ball 15 rides on the stepped portion 19a.
4 shows the relationship. The ball 15, which has moved in the radial direction by the length H, is released from the strong wedge action of being pressed by the notch 14 at two points. In this state, the ball 15
Is the pressure plate 30, the flat portion 19 and the step portion 1.
It is held by the three members 9a and can roll freely.
When the ball 15 rolls, the ball 15 and the notch 14
Since the gap C is secured between the two, the rotation of the ball 15 is not restricted.

As a result, the hub 10 can rotate idly, and the rotational torque can be reliably released.

According to the above ball clutch, the ball 1
5 is a valley portion 14a of the notch 14 due to the inclined portion 31,
The hub 1 is pressed by the ball holding bottom portion 18 which is a V-shaped groove,
The structure in which two points are respectively supported between 0 and the driven plate 17 does not cause a phase shift between the hub 10 and the driven plate 17 even if the rotation direction of the hub 10 changes.

Further, when the overload is cut off, the ball 15 starts to move with the valley 14a as a guide. Supported by and released from the two-point contact with the valley 14a of the hub notch 14 to make a rolling contact.

When the re-engagement position is reached after the overload is released, the ball 15 surely falls into the ball holding bottom portion 18 of the driven plate 17 and comes into two-point contact with the trough portion 14a. That is, they mesh without backlash.

Further, the balls 15 are connected to the hub 1 by a wedge action during torque transmission.
Since it is always in contact with 0 at two points, it will settle at a predetermined position regardless of the processing accuracy of the notch 14, and it becomes unnecessary to remove strain after heat treatment and the notch 14 can be manufactured at low cost.

The notch 14 may be a divergent penetrating portion.

Further, as shown in FIG. 9, the position of the collar of the hub and the position of the driven plate may be reversed from those in FIG. In this case, the V-shaped penetrating portion 5 having the ball holding bottom portion 52 on the flange 51 of the hub 50 and the trough portion 54a on the driven plate 53.
4 are formed respectively. Reference numeral 55 is a retaining ring that regulates the position of the driven plate 53. In the case of this embodiment, the penetrating portion 54
Is a penetrating portion and is not a notch literally, so it is not necessary to prevent the ball from coming out by forming the left end of the pressure plate 30 into a sleeve shape as in the case of FIG.

Further, the notch 14, the through portion 54, the ball holding bottomed groove 1
The 8, 52 may be formed at equal intervals.

EFFECTS OF THE INVENTION As described above, according to the overload clutch of the present invention, at the time of meshing, the torque transmission element does not loosely fit into the torque transmission element holding through portion and is always in contact with two points. The position with respect to the element holding penetrating portion is always constant, and the relative position between the hub and the driven plate does not deviate. Further, even after the overload is removed, the torque transmission element surely enters the bottom portion of the torque transmission element holding portion, so that the re-engagement is ensured.

Further, since the shape of the torque transmission element holding penetrating portion is a shape that does not require precision, machining becomes easier and cost can be reduced.

Further, when the overload is cut off, the torque transmission element is released from the two-point contact with the torque transmission element holding penetrating portion, and comes into rolling contact between the pressure plate and the driven plate. Therefore, the phase alignment for returning to the re-engagement becomes extremely light, and seizure and wear phenomenon at high speed rotation can be suppressed.

[Brief description of drawings]

1 to 9 show an embodiment of an overload clutch according to the present invention, wherein FIG. 1 is an axial cross-sectional view, and FIG. 2 is a view of a hub as viewed in the direction of line 2-2 in FIG. FIG. 3 is a view of the driven plate taken along line 3-3 of FIG. 1, FIG. 4 is a view of FIG. 3 taken along line 4-4, and FIG. 5 is a partially enlarged perspective view of the driven plate. FIG. 6 is a partial cross-sectional view showing the relationship between the torque transmission element at the time of meshing and the torque transmission element holding bottom portion, and FIG. 7 is a partial cross-sectional view of the torque transmission element at the time of overload cutoff and the flat portion and inclined step portion, FIG. 8 is a front view showing the relationship between the torque transmission element and the torque transmission element holding penetrating portion when the overload is cut off, and FIG. 9 is an axial sectional view showing another embodiment. 10, 50 ... Hub 13, 51 ... Collar 14 ... Notch (torque transmitting element holding penetrating portion) 14a ... Valley 15 ... Ball (torque transmitting element) 17, 53 ... Driven plate 18 ... Ball holding bottom (torque transmitting element holding) Bottom part) 19 ... Flat part 19a ... Inclined step part 30 ... Pressure plate 31 ... Inclined part 54 ... Penetration part (torque transmission element holding penetration part)

Claims (1)

[Claims] 1. A torque transmission element holding through portion formed on one of a hub and a driven plate holds a torque transmission element, and a pressure plate presses a torque transmission element holding bottom portion formed on the other of the hub and the driven plate. In an overload clutch that performs torque transmission and that the torque transmission element escapes from the torque transmission element holding bottom portion against the pressing at the time of overload, in the portion of the pressure plate that contacts the torque transmission element. The torque transmission element is formed with an inclined portion that presses the torque transmission element in a direction intersecting with the rotation center axis of the overload clutch, and the torque transmission element holding penetrating portion has a V shape when viewed in the axial direction. The holding bottom portion is a V-shaped groove, and is provided between the torque transmission element holding bottom portion. On the carrier part, the angle of inclination of the inclined part of the pressure plate is larger than the pitch circle of the torque transmission element in the two-point contact state with the torque transmission element holding penetration part on the valley side of the torque transmission element holding penetration part. Overload clutch with angled ramps.