JPH0129310Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement of a centrifugal belt transmission.

(Prior art and its problems) Among motorcycles, motorcycles have a relatively small engine output and a small torque transmitted to the drive wheels, and rubber is mainly used as a means to transmit the rotation of the engine crankshaft to the drive wheels. A drive belt is used, and the transmission uses the centrifugal force generated as the engine speed increases to automatically change the pitch of the pulley on the crankshaft side, and the pitch on the drive wheel side changes accordingly. A centrifugal belt transmission with a variable rotation ratio is generally used to make driving easier.

As shown in FIG. 1, such a centrifugal belt transmission conventionally includes a fixed pulley half 2 fixed to a rotating shaft 1, and a central cylindrical boss portion 4a attached to the rotating shaft 1 in the axial direction via a bearing 5. A movable bowl-shaped member is slidably fitted, and the inner side of the outer circumferential wall 4b is connected to the outer circumferential portion of the inclined plate 3 by spline coupling means 6 such that it is movable in the axial direction but cannot be moved in the circumferential direction. The rotating shaft 1 of the inclined plate 3 is disposed between the pulley half 4 and the annular inclined plate 3 fixed to the back surface of the movable pulley half 4 and the rotating shaft 1, and is rotated by the centrifugal force during rotation. a weight 7 that moves the movable pulley half 4 toward the fixed pulley half 2 by moving along the inclined portion 3b on the outer peripheral side from the attachment portion 3a to the fixed pulley half 2 and the fixed pulley half 2; There is known a device in which the pitch of the belt 8 attached between the movable pulley half body 4 is changed (Japanese Utility Model Publication No. 152847/1983).

In such a conventional centrifugal belt transmission, the attachment part 3a of the inclined plate 3 to the rotating shaft 1 is flat and connected to the inclined part 3b without a step, so that the rigidity of the inclined plate 3 is reduced. Due to the wedge effect caused by the weight 7 during rotation, the inclined plate 3 is slightly bent. The cylindrical boss portion 4a is distorted, and its axis cannot be kept parallel to the axis of the rotating shaft 1, causing the intersection angle between the belt sliding surface of the movable pulley half 4 and the axis of the rotating shaft 1 to become ``This phenomenon is hereinafter referred to as (falling down)'' where the angle is deviated from the initial setting angle. As the belt groove width between the fixed pulley half 2 and the movable pulley half 4 changes due to the tilting of the movable pulley half 4, the position of the belt 8 with respect to the belt groove becomes inaccurate. However, there was a problem in that the belt speed ratio was likely to become unstable. In order to solve this problem, the movable pulley half 4
It is conceivable to extend the axial length of the central cylindrical boss portion 4a and the bearing 5 toward the side opposite to the movable pulley half 2, but extending the axial length toward the opposite to the movable pulley half 2 side is
This is impossible because the mounting portion 3a of the inclined plate 3 will get in the way. However, the only way to solve the above problem is to increase the rigidity of the movable pulley half 4. In order to increase the rigidity of the movable pulley half 4, the axial length of the outer peripheral wall 4b must be made longer than the axial length of the central cylindrical boss portion 4a of the movable pulley half 4. In this case, the weight of the movable pulley half 4 increases and its rotational mass increases, so the rotating shaft 1
There is a problem in that the belt speed ratio has a poor ability to follow rotational fluctuations.

(Purpose of the invention) The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a centrifugal belt transmission device which stabilizes a belt transmission ratio by preventing the position of the belt from becoming inaccurate, and improves the ability of the belt transmission ratio to follow rotational fluctuations.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, a fixed pulley half is fixed to a rotating shaft, and a central cylindrical boss is attached to the rotating shaft via a bearing. a bowl-shaped movable pulley half fitted to be slidable in a direction; a weight disposed between a back surface of the movable pulley half and an annular inclined plate fixed to the rotating shaft; In the centrifugal belt transmission device, wherein the pitch of the belt installed between the fixed pulley half and the movable pulley half is changed, the attachment portion of the inclined plate to the rotating shaft is connected to the inclined plate. providing a stepped portion from the inclined portion to bulge out over the entire circumference of the movable pulley half toward the side opposite to the movable pulley half, and to improve rigidity;
The central cylindrical boss portion of the movable pulley half extending from the end surface of the outer circumferential wall of the movable pulley half and the respective end surfaces of the bearing protrude from the bulging portion.

(Function) By bulging the mounting part of the inclined plate toward the opposite side of the movable pulley half by providing a stepped part from the inclined part to improve the rigidity, the rigidity of the inclined plate is increased and its convexity is suppressed. Of course, it is possible to extend the axial length of the central cylindrical boss portion of the movable pulley half and the bearing toward the side opposite to the movable pulley half by the amount of the bulge. Further, since the axial length of the central cylindrical boss portion of the movable pulley half and the bearing becomes longer by the length of the extension, the movable pulley half becomes less likely to fall. Therefore, the change in belt groove width between the fixed pulley half and the movable pulley half due to the tilting of the movable pulley half due to the convexity of the inclined plate is drastically reduced, and the position of the belt relative to the belt groove becomes accurate. The belt gear ratio becomes stable. Furthermore, since the movable pulley half does not easily fall down, the axial length of the outer circumferential wall of the movable pulley half can be made shorter than the axial length of the central cylindrical boss. Since the half body is lightweight, its rotating mass is reduced, and the belt speed ratio can better follow rotational fluctuations of the rotating shaft.

(Example) Hereinafter, an example of the present invention will be described in detail based on FIG. 2. FIG. 2 shows a cross section of the centrifugal belt transmission of the present invention. In the figure, 10 is a rotating shaft connected to an engine (not shown), and one end 10a of the rotating shaft has an inclined plate 11, a sleeve 12, and a fixed pulley. The halves 13 are fitted, and these are firmly tightened and fixed to the rotating shaft 10 by a nut 14. In the sleeve 12, a central cylindrical boss portion 16a of a bowl-shaped movable pulley half 16 is located between the inclined plate 11 and the fixed pulley half 13 and is movable in the axial direction via a bearing 15. It is fitted.
A weight 17 is disposed between the movable pulley half 16 and the inclined plate 11. A stepped portion 11c is formed around the entire circumference of the inclined plate 11 between the attachment portion 11a to the rotating shaft 10 and the inclined portion 11b on the outer circumferential side thereof, so that the attachment portion 11a is attached to the inclined plate. 11 and bulges out toward the side opposite to the movable pulley half 16. The inclined portion 11b of the inclined plate 11 is connected to the movable pulley half 1.
It is inclined toward the 6th side at a predetermined angle and formed into a substantially dish shape.

The inclined plate 11 having such a shape is integrally formed with a metal plate, and therefore, the rigidity (strength) of the inclined plate 11 itself is improved by providing the stepped portion 11c. Central cylindrical boss portion 1 of the movable pulley half 16
6a and each end face of the bearing 15 are connected to the movable pulley half 1.
6 protrudes from the end face of the outer peripheral wall 16b toward the side opposite to the fixed pulley half 13 and into the bulge of the inclined plate 11. The rigidity of the movable pulley half 16 is ensured by making it into a bowl shape.
As in the present invention, each end face of the central cylindrical boss portion 16a of the movable pulley half body 16 and the bearing 15 is made to protrude from the end face of the outer circumferential wall 16b of the movable pulley half body 16 to the side opposite to the movable pulley half body 16. , that is, the axial length of the central cylindrical boss portion 16a and the bearing 15 is set to the mounting portion 1.
(The axial length of the conventional central cylindrical boss 16a and bearing 1a is A in the figure, whereas the central cylindrical boss 16a and bearing 1 of the present invention
The axial length of No. 5 is B in the figure. ) Movable pulley half 16
By cutting the length of the outer peripheral wall 16b shown by the broken line in the figure, the length of the outer peripheral wall in the conventional case (C in the figure) is obtained.
The movable pulley half 16 can be made shorter as shown by D in the figure, thereby reducing the weight of the movable pulley half 16, reducing its rotational mass, and improving the followability of the belt speed ratio due to rotational fluctuations of the movable pulley half 16. The outer circumferential portion of the inclined plate 11 is coupled to the inner side of the outer circumferential wall 16b of the movable pulley half 16 by spline coupling means 18 so as to be movable in the axial direction but immovable in the circumferential direction. In addition, 19 in the figure is a belt.

Further, the inclined plate 11 has a stepped portion 1 between the mounting portion 11a and the inclined portion 11b due to the swelling of the mounting portion 11a.
Since the rigidity is improved by 1c, the weight 1
Even if a pressing force is applied to the inclined portion 11b by 7, the inclined plate 11 will not bend. Therefore, weight 17
As a result, the movable pulley half 16 is less likely to fall due to the movement of the fixed pulley half 1 due to the fall of the movable pulley half 16 due to the deflection of the inclined plate 11.
3 and the movable pulley half 16 is reduced so that the belt 19 with respect to this belt groove is
The position of the belt becomes accurate and the belt gear ratio becomes stable.
Further, the bearing 15 of the movable pulley half 16 and the central cylindrical boss portion 1 are separated by the distance of the stepped portion 11c of the inclined plate 11.
The axial length of the movable pulley half 16 is increased, and as a result, the slidability and durability of the sliding portion of the movable pulley half 16 including the spline coupling means 18 are improved.

(Effects of the Invention) As described above, the centrifugal belt transmission of the present invention has rigidity at the attachment part of the inclined plate to the rotating shaft over the entire circumference of the inclined plate and toward the side opposite to the movable pulley half. In order to improve this, a stepped portion is provided and bulged from the inclined portion, and the central cylindrical boss portion of the movable pulley half extending from the end surface of the outer peripheral wall of the movable pulley half and each of the bearings are attached to the bulged portion. It is characterized by having a protruding end surface.

Therefore, by providing a stepped portion and bulging out the mounting portion of the inclined plate toward the side opposite to the movable pulley half in order to improve the rigidity, the rigidity of the inclined plate is increased and its canopy is increased. Of course, this can be suppressed, and the axial length of the central cylindrical boss portion of the movable pulley half and the bearing can be extended toward the side opposite to the movable pulley half by the amount of the bulge. In addition, since the axial length of the central cylindrical boss part of the movable pulley half and the bearing becomes longer by the length of the extension, the movable pulley half becomes difficult to fall, and the movable pulley half falls due to the convexity of the inclined plate. Changes in the width of the belt groove caused by this are drastically reduced, the position of the belt relative to the belt groove becomes accurate, and the belt transmission ratio becomes stable. Furthermore, since the movable pulley half is difficult to fall over,
Therefore, the axial length of the outer peripheral wall of the movable pulley half is
It can be made shorter than the axial length of the central cylindrical boss, and the shorter movable pulley half becomes lighter, its rotating mass becomes smaller, and the belt speed ratio can better follow the rotational fluctuations of the rotating shaft. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional centrifugal belt transmission, and FIG. 2 is a longitudinal sectional view showing an embodiment of the centrifugal belt transmission according to the present invention. 10... Rotating shaft, 11... Inclined plate, 11a...
Mounting part, 11b...slanted part, 11c...stepped part,
13...Fixed pulley half, 15...Bearing, 16...
...Movable pulley half, 16a...Central cylindrical boss part,
16b...Outer peripheral wall.

Claims (1)

[Scope of utility model registration request] a fixed pulley half fixed to a rotating shaft; a bowl-shaped movable pulley half having a central cylindrical boss fitted to the rotating shaft so as to be slidable in the axial direction via a bearing;
a weight disposed between the back surface of the movable pulley half and an annular inclined plate fixed to the rotating shaft, the weight being mounted between the fixed pulley half and the movable pulley half; In a centrifugal belt transmission device in which the pitch of the belt is changed, the mounting portion of the inclined plate to the rotating shaft is made rigid by extending the entire circumference of the inclined plate toward the opposite side of the movable pulley half. In order to improve the appearance, a step part is provided from the slope part to bulge out,
A centrifugal belt transmission device characterized in that a central cylindrical boss portion of the movable pulley half extending from an end surface of an outer circumferential wall of the movable pulley half and each end surface of a bearing protrude from the bulging portion.