JPH0716917Y2 - Friction transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a power transmission acceleration / deceleration device, and more particularly to a friction transmission device that transmits rotational power by frictional force between rollers.

[Prior Art] FIG. 6 is a longitudinal sectional view of a conventional friction transmission device, and FIG. 7 is a transverse sectional view thereof. However, the dimensional relationships do not match. In the figure, 1 and 2 are casings, 3 and 4 are shaft holes, 5 and 6 are bearings, 7 and 8 are rotating shafts, and 77 and 88 are rollers.

The rollers 77 and 88 are integrally or integrally fixed to the rotary shafts 7 and 8, respectively. The rotary shaft 7 is supported by bearings 5, 5 provided in the shaft holes 3, 3 of the casing 1, and the rotary shaft 8 is supported by bearings 6, 6 provided in the shaft holes 4, 4 of the casing 2. Make sure that the outer peripheral surfaces of both rollers 77 and 88 are in strong contact with each other.
As shown in FIG. 7, casings 1 and 2 are tightened with bolts and nuts.

As shown in FIG. 8, if the rollers 77 and 88 are pressed by the force P, the contact point between the rollers 77 and 88 is fP.
Then, the rotational torque of one roller is transmitted to the other roller. However, f is a kind of friction coefficient called a traction coefficient.

[Problems to be solved by the invention] The conventional friction transmission device is as described above.
The transmission force is determined by the frictional force, which is the product fP of the pressing load P of 8 and the traction coefficient f. However, as shown in FIG. 9, the traction coefficient f changes depending on the slip rate S, and the maximum traction coefficient fm at a certain slip rate Sm.
It becomes ax. Therefore, in Fig. 9, when the slip rate S is on the right side of Sm, the traction coefficient decreases with the increase of the slip rate, so that power cannot be transmitted. Therefore, the load should be set so that the slip rate S is on the left side of Sm. Determine P.

However, at startup, the slip rate S is small, the traction coefficient f is small, and even if the rotation on the drive side increases, the driven side also has an inertial force and the rotation does not increase, and the slip rate S rapidly increases. The maximum traction coefficient fmax at the point is exceeded, the traction coefficient f becomes small and becomes unstable, torque cannot be transmitted, and the start fails.

In order to prevent this, it is sufficient to increase fP, but since it is difficult to increase the traction coefficient f, the load P may be increased. However, if the load P increases, the contact stress between the rollers increases, shortening the rolling life of the rollers,
There was a problem that bearing loss and the like would also increase.

The present invention has been made in order to solve such a problem, and an object thereof is to obtain a friction transmission that can be activated without increasing the load P and without the above-mentioned adverse effects.

[Means for Solving the Problems] In the friction transmission device according to the present invention, it is possible to make the direction of the line connecting the centers of both rollers different from the direction of the load pressing the both rollers. The shape of the shaft hole for supporting the rotary shaft of one roller is an arc-shaped elongated hole formed by an arc centered on the center of the other roller.

[Operation] In the friction transmission device according to the present invention, at the time of start-up, the center of one roller is moved along the arc-shaped long hole, and the direction of the line connecting the centers of both rollers is the direction of the load pressing both rollers. If the directions are different, the frictional force increases due to the component force of the pressing force and the frictional force, and the torque transmission at the time of starting becomes easy. Also, during steady operation, if the center of one roller is moved along the arcuate slot and the direction of the line connecting the centers of both rollers is made to match the direction of the load that pushes both rollers, the above component force Is eliminated, the load during steady operation is reduced, and wear of bearings and the like is reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a friction transmission device according to an embodiment showing the basic concept of the present invention. In the figure, 1 and 2 are casings, 3 and 4 are shaft holes, 5 and 6 are bearings, 7 and 8 are rotating shafts, and 77 and 88 are rollers.

Since the general structure and function are similar to those of the conventional example, the description thereof will be omitted. The direction of the load applied from the bearings 5 and 6 mounted in the shaft holes 3 and 4 of the casings 1 and 2 by the bolts and nuts to the contact portions of the rollers 77 and 88 through the rotating shafts 7 and 8 is the vertical direction 1 in the figure.
This is the direction of the dashed line. As a feature of the structure, the bearing 5 and the shaft hole 3 are laterally displaced, and the rotary shaft 7 and the roller 77 are laterally displaced. Laura 88 center O ₂
And the line connecting the center O _{1 of the} roller 77 and the load direction line are θ
It makes an angle.

Since the load direction line and the line connecting the centers O ₂ and O ₁ of both rollers form an angle of θ, in addition to the pressing load, a component force of tan θ is generated at the contact part of both rollers, increasing the frictional force. And start up easily.

Since the traction coefficient fmax is usually smaller than 0.1, it is practical to set the angle θ to 6 degrees or less.

FIG. 2 shows a concrete embodiment of this invention. In this embodiment, the shaft hole 3 of the casing 1 has a horizontally elongated hole shape.
The shape of the shaft hole 3, in FIG, AB is O ₂ A about the O ₂
Arc with BC as radius, BC with O ₀ as center and O ₀ B with radius, CD with O ₂ as center and O ₂ C with radius, D-
A is an arc whose center is O ₁ and whose radius is O ₁ D. However, O ₂ is the center of the roller 88 and O ₀ is the roller on the load direction.
The center of 77, O ₁ is the center of the roller 77 in the direction deviated by θ from the load direction. The length between O ₂ -O ₀ and the length between O ₂ -O ₁ are equal, A and D are on the O ₂ O ₁ line, and B and C are on the O ₂ O ₁ line.

In this embodiment, the center of the roller 77 is placed at the position of O ₁ which is deviated from the load direction by θ and is started, and is returned to the position of O ₀ in the steady operation. As a result, a large frictional force is obtained at the time of starting, and a normal frictional force is obtained at the time of steady operation.

FIG. 4 shows changes in the frictional force of the frictional transmission shown in FIG. 1, and FIG. 5 shows changes in the frictional force of the frictional transmission shown in FIG.

[Effect of the Invention] As described above, according to the present invention, the torque transmission at the time of starting can be facilitated by setting the direction of the line connecting the centers of both rollers to be different from the direction of the pressing load at the time of starting. By making the direction of the line connecting the centers of both rollers coincide with the direction of the pressing load during steady operation, the load during steady operation is reduced, and a friction transmission device with less wear of bearings and the like can be obtained.

[Brief description of drawings]

FIG. 1 is a transverse sectional view of a friction transmission device according to an embodiment showing the basic concept of the present invention, FIG. 2 is a transverse sectional view of a friction transmission device according to a concrete embodiment of the present invention, and FIG. ,
FIG. 4 is a diagram showing a change in friction force of the friction transmission device shown in FIG. 1, and FIG. 5 is a diagram showing a change in friction force of the friction transmission device shown in FIG. FIG. 6 is a vertical sectional view of a friction transmission device according to a conventional example, and FIG. 7 is a sectional view taken along line VII-VII of FIG.
FIG. 8 is an explanatory diagram of friction transmission, and FIG. 9 is a traction coefficient f.
FIG. In the figure, 1 and 2 are casings, 3 and 4 are shaft holes,
Reference numerals 5 and 6 are bearings, 7 and 8 are rotating shafts, and 77 and 88 are rollers.

Claims (1)

[Scope of utility model registration request] 1. In a friction transmission device in which rollers of both rotary shafts are pressed to transmit rotational power by frictional force, the direction of the line connecting the centers of both rollers is different from the direction of the load pressing the rollers. In order to be able to do so, the shape of the shaft hole for supporting the rotation shaft of one roller is an arc-shaped elongated hole formed by an arc centered on the center of the other roller. Friction transmission device.