JPH0451223Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention includes a clutch drum, a radially movable member disposed within the clutch drum, and a radially movable member that moves radially outwardly under the action of centrifugal force to move the clutch drum. A plurality of clutch shoes that can come into frictional contact with the inner peripheral surface, and a plurality of clutch shoes that are disposed in an arcuate groove formed in the clutch shoes and bias the clutch shoes radially inward to normally separate the clutch shoes from the inner peripheral surface of the clutch drum. The present invention relates to a centrifugal clutch of the type having an annular coil spring that maintains the centrifugal clutch.

BACKGROUND OF THE INVENTION In conventional centrifugal clutches of this type, an annular coil spring is placed in direct contact with the radially inner surface of a circumferential groove of the clutch. When such a centrifugal clutch is used in a high-speed rotating machine such as a chainsaw, in a rotational speed range where the centrifugal force acting on the annular coil spring exceeds the mounting load of the annular coil spring, the annular coil spring will move into the circumferential groove of the clutch. is raised radially outward from the radially inner surface of the clutch, creating a relative sliding friction motion between the annular coil spring and the inner surface of the circumferential groove of the clutch, which accelerates wear of the annular coil spring. This has the disadvantage that the annular coil spring is prematurely broken and its durability is impaired.

Problems to be Solved by the Invention Therefore, the object of the present invention is to eliminate the drawbacks of the conventional centrifugal clutch and provide a simple and convenient centrifugal clutch.

Means for Solving the Problems That is, the centrifugal clutch according to the present invention prevents the annular coil spring from floating radially outward from the arcuate groove due to centrifugal force between the clutch groove and the annular coil spring. It is characterized by a structure in which a covering member made of a non-slip elastic material is interposed.

Function Therefore, according to the configuration of the present invention, the annular coil spring does not come into direct contact with the inner surface of the groove of the clutch shoe, but indirectly through the tubular covering member made of a non-slip elastic material. , sliding frictional motion is suppressed, and early wear and breakage of the annular coil spring can be prevented.

Embodiments Next, the present invention will be explained based on embodiments shown in the drawings.

The centrifugal clutch 1 of this embodiment is of a type suitable for being installed in a power transmission device of a working machine such as a chainsaw that is required to transmit rotational force at a relatively high speed. 1 has a clutch boss 2 attached to a drive side such as an output shaft D of an internal combustion engine, and a clutch drum 3 attached to a driven side connected to a saw chain sprocket S of a chainsaw or the like, and the clutch boss 2 and The clutch drum 3 is arranged coaxially with the output shaft D and rotatable independently of each other. In this example, the clutch boss 2 has four radially outwardly projecting protrusions 4 integrally formed and having a rectangular cross section and spaced apart from each other at an angle of 90 degrees.
are each mounted for radial movement as described below. Since these four sets of protrusions 4 and clutches 5 are constructed in the same way, only one set will be described.

The clutch 5 has a cut groove 7 formed in the center of its radially inner end 6 to extend in the radial direction, and a cut groove 7 that is spaced radially outward from a radially bottom end 8 of the cut groove 7. The axial ends 9 on both sides
and circumferential arcuate grooves 11 and 12 formed at positions 10. Further, the clutch 5 has a pair of axial holes 13 on both sides of the cut groove 7.
and 14, and these holes 13, 14
Appropriate screws (not shown) are inserted through these screws, and the fan-shaped side plates 15 and 16 are fixed to both ends 9 and 10 of the clutch shoe 5, respectively. One side plate 15 closes one of the axially open surfaces of the cut groove 7 of the clutch shoe 5 and also closes the open surface of one arcuate groove 11, and the other side plate 16 closes the open surface of the cut groove 7 of the clutch shoe 5. It is arranged so as to close the other axially open surface of the arcuate groove 12 and to close the open surface of the other arcuate groove 12 . In this way, the cut groove 7 of the clutch shoe 5 defines a radial hole with a square cross section together with the side plates 15 and 16, into which the protrusion 4 of the clutch boss 2 fits, thereby moving the clutch shoe 5 in the radial direction. It is guided so that it can be moved relative to. The radially outer end 17 of the clutch shoe 5 is formed in a shape complementary to the inner circumferential surface 18 of the clutch drum 3, so that when the clutch shoe 5 moves radially outward due to the action of centrifugal force during operation, the clutch shoe 5 The radially outer end 17 of the clutch drum 3 is in pressure contact with the inner circumferential surface 18 of the clutch drum 3 over substantially its entire surface.

With this configuration, the arcuate groove 11 on one side of the four clutches 5 forms one continuous circular groove 19 in the circumferential direction, and at the same time, the arcuate groove 12 on the other side of the four clutches 5 forms one continuous circular groove 19 in the circumferential direction. One continuous circumferential circular groove 20 is formed.

Annular coil springs 21 and 22 are installed in the circular grooves 19 and 20 on both sides, respectively. Each of the annular coil springs 21 and 22 is made of arcuate grooves 11 and 1 made of silicone rubber, for example.
2 is covered by tubular covering members 23 and 24 made of a non-slip elastic material. Therefore, the annular coil springs 21 and 22 do not come into direct contact with the inner surfaces of the arcuate grooves 11 and 12 formed in the clutch shoe 5, but rather come into contact via the non-slip tubular covering members 23 and 24, which causes sliding friction. is suppressed, and all the clutches 5 are biased radially inward to maintain a position radially inwardly away from the clutch drum 3 under normal conditions.

The covering member may partially cover the annular coil spring, or may be filled with a non-slip elastic material after the annular coil spring is installed in the arcuate groove.

Effects of the invention With the structure of the invention explained above, the invention has the following effects:
By interposing a covering member made of a non-slip elastic material between the annular coil spring and the arcuate groove, the annular coil spring is lifted radially outward from the radially inner surface of the groove of the clutch shoe. Since it effectively prevents relative sliding movement and abnormal vibration between the clutch and the clutch, it prevents premature wear and breakage of the annular coil spring and greatly increases its durability. play.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of a centrifugal clutch according to the present invention, and FIG. 2 is a front view of an essential part of the centrifugal clutch shown in FIG. 1... Centrifugal clutch, 3... Clutch drum,
5... Clutch shoe, 11, 12... Arc-shaped groove, 18... Inner peripheral surface, 21, 22... Annular coil spring, 23... Covering member made of a non-slip elastic material.

Claims (1)

[Scope of utility model registration request] a clutch drum 3; a plurality of clutches 5 disposed radially movably within the clutch drum and capable of moving radially outwardly under the action of centrifugal force into frictional contact with the inner circumferential surface 18 of said clutch drum; The clutch is disposed in arcuate grooves 11 and 12 formed in the clutch, and biases the clutch inward in the radial direction so that the clutch is in the inner circumferential surface 1 of the clutch drum in a normal state.
annular coil springs 21, 22 maintained apart from 8;
In the centrifugal clutch 1 of the type having the arcuate grooves 11, 12 and the annular coil spring 21,
Covering members 23 and 24 made of a non-slip elastic material are interposed between the annular coil springs 21 and 22 to prevent them from floating radially outward from the arcuate grooves 11 and 12 due to the centrifugal force of the annular coil springs 21 and 22. A centrifugal clutch characterized by: