JPS6224659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power transmission device using a belt, which is used, for example, in an automobile to transmit engine rotation to auxiliary equipment such as an air pump, water pump, fan, compressor, alternator, etc. and is valid. Another object of the present invention is to provide a power transmission device that is lightweight, easy to process, and has excellent durability.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes a drive shaft, which in this example is a crankshaft of an automobile engine (the direction of rotation is represented by P). A main shaft 11 is integrally fixed to the drive shaft 1 with a bolt 15 and a key (not shown).

A dry bearing 12 is driven into the movable pulley 14 and slides on the main shaft 11 in the axial direction as the movable pulley 14 moves. A fixed pulley 13 is integrally fixed to the main shaft 11 with a bolt 15 and a key (not shown). The drive side pulley 1 is connected to the fixed pulley 13 and the movable pulley 14.
0 is formed. Therefore, the width and diameter of the driving pulley 13 is variable, and the spring 16 applies an initial setting load to move the movable pulley 14 toward the fixed pulley 13. In other words, the driving pulley 10 changes in width. It acts in the direction of narrowing. Note that both the fixed and movable pulleys 14 are made of a relatively lightweight metal material such as an aluminum alloy in order to reduce the weight of the device.

Further, reference numeral 17 denotes a stationary cam that is integrally fixed to the main shaft 11 and has an operating surface 17a. A movable cam 18 is integrally fixed to the movable pulley 14 and has an operating surface 18a having the same angle as the operating surface 17a of the fixed cam 17. A driving cam mechanism 19 is formed by the fixed cam 17 and the movable cam 18. In this cam mechanism 19, the working surfaces 17a and 17b of both the cams 17 and 18 are in constant contact, so when a relative movement occurs between the two cams 17 and 18, the working surfaces 17a and 17b correspond to the load torque. A force determined by the angle of 18a is applied to the working surfaces 17a, 18a.

Reference numeral 21 is a driven shaft supported by a bearing (not shown) and mounted on an engine block or the like.
A dry bearing 22 is driven into the movable pulley 24 similarly to the drive side unit 10, and is capable of sliding on the driven shaft 21 in the axial direction. 23
is a fixed pulley, and the driven shaft 21 is connected with a key (not shown).
It is integrally fixed to. A V-groove portion 23a is cut into the fixed pulley 23, and power is transmitted to automobile auxiliary equipment such as an air pump, water pump, fan, compressor, and alternator via a V-belt 41. In addition,
In FIG. 1, only two V-grooves 23a are shown, but in reality, a large number of V-grooves 23a are provided.

And this fixed pulley 23 and movable pulley 2
4 forms a driven pulley 20. Like the driving pulley 10, this driven pulley 20 is also made of a relatively lightweight aluminum alloy and has a variable width and diameter. A spring 27 is used for initial setting and acts in a direction to move the movable pulley 24 away from the fixed pulley 23, that is, in a direction to make the driven pulley 20 wider.

An annular protrusion 24a is formed on a portion of the movable pulley 24 opposite to the surface that contacts the belt 40, and the outer side surface of the annular protrusion 24a has a second surface that coincides with the radial direction of the driven shaft 21. It forms a flange surface 24b, and on the inner circumferential side of the second flange surface 24b, there are grooves at three locations equidistantly spaced in the circumferential direction at positions shifted from the belt 40 side in the axial direction of the driven shaft 21. 24d is formed, and the bottom surface of this groove 24d forms a first flange surface 24c that coincides with the radial direction of the driven shaft 21.

A holder 29 is fitted into each groove 24d of the movable pulley 24, as shown in FIG. It comes into close contact with the flange surfaces 24c and 24b of.
As shown in FIG. 2, the holder 29 has an arc shape that follows the shape of the movable pulley 24, and has two inclined surfaces 29a in the radial direction of the movable pulley 24.
is formed.

A fixed plate 25 is fixed to the driven shaft 21 with a nut 26 so as to cover the holder 29. Therefore, although the fixed plate 25 rotates together with the driven shaft 21, it does not move in the axial direction of the driven shaft 21.

Reference numeral 28 denotes a flyweight held between the fixed plate 25 and the inclined surface 29a of the holder 29. The flyweight 28 rotates together with the movable pulley 24 and pushes the holder 29 with centrifugal force caused by rotation. Therefore, the fly weight 2
8 requires a predetermined amount of weight, and the coefficient of friction between the flyweight 28 and the holder 29 needs to be small.

Therefore, in this example, the fly weight 28 is made of steel, and carbon fiber is bonded to the outer periphery of the fly weight 28. Specifically, a cloth-like carbon fiber with a wall thickness of about 0.1 to 0.2 mm whose surface is coated with epoxy resin is placed so that the direction of the fiber is inclined at 45 degrees with respect to the central axis direction of the fly weight 28, and the fiber is Approximately four layers are wound around the outer periphery of the flyweight 28 so that the directions are perpendicular to each other, and the carbon fibers are heated and compressed in this state to melt the epoxy resin and bond the carbon fibers to the outer periphery of the flyweight 28. However, this flyweight 28 only needs to be made of a material that has excellent self-lubricating properties and has a predetermined weight. Therefore, in addition to the above-mentioned materials, self-lubricating materials such as spheroidal graphite cast iron or oil-impregnated sintered metal may be used. Of course, a metal material may also be used.

At the same time, the holder 29 and the fixing plate 25 are also required to have considerable strength and wear resistance in order to retain the centrifugal force of the fly weight 28. Therefore, in this example, carburized and quenched carbon steel is used as the material for the holder 29 and the fixing plate 25.

A fixed cam 31 is integrally formed with the fixed pulley 23, and like the fixed cam 17 of the drive unit 10, it has an operating surface 31a formed into a calculated straight line and at a constant angle. There is.
(As shown in FIG. 3) However, this working surface 31a is in the opposite direction to the fixed side cam 17 on the drive side. 32
is a movable side cam, which is integrally formed with the movable pulley 24, and has an operating surface 32a having the same angle as the operating surface 31a. A driven side cam mechanism 33 is formed by these cams 31 and 32, and like the driving side cams 17 and 18, the driven side cams 31 and 32 are
Made of material with excellent durability and wear resistance.

40 is a driving pulley 10 and a driven pulley 2
This is a variable speed V-belt that is stretched between the drive pulley 10 and the driven pulley 20, and is made of rubber with a strong core.

The driven pulley 20 having the above configuration is assembled as follows.

That is, first, the dry bearing 22 and the movable side cam 32 are driven and fixed to the inner circumference of the movable pulley 24, and the holder 2 is attached to the first flange surface 24c and the second flange surface 24b of the movable pulley 24.
9, the holder 29 is inserted into the groove 2 of the movable pulley 24 with both ends 29b and 29c of the inner and outer peripheries of the
4d and fix it.

Thereafter, the fixed pulley 23 is keyed to the driven shaft 21, and the spring 27 is inserted from the end of the shaft 21. Next, the fly weight 28 is arranged so as to be in contact with the inclined surface 29a of the holder 29, and finally, the fly weight 28 is covered from the outside with the fixing plate 25, and the fixing plate 25 is fixed to the driven shaft 21 with the nut 26. to finish the assembly.

Next, the operation of the power transmission device having the above configuration will be explained.

As the engine speed increases from idling, the driving pulley 10 and driven pulley 20 also rotate at high speeds, and as a result, the centrifugal force of the flyweights 28 increases, acting on the inclined surface 29a of the holder 29, causing the holder 29 to The component of the force that presses the movable pulley 24 toward the fixed pulley 23 through In a range smaller than the proportional force, the movable pulley 24 does not move in the axial direction, and transmission is performed at a predetermined constant speed ratio.

Next, when the force acting to move the movable pulley 24 due to the centrifugal force of the flyweight 28 exceeds a force proportional to the total load of the springs 16 and 27, the movable pulley 24 moves toward the fixed pulley 23, and as a result, the driven pulley 24 moves toward the fixed pulley 23. The width of the side pulley 20 becomes narrower, and the part where the V-belt 40 contacts becomes farther away from the driven shaft 21, and the drive side pulley 1 becomes narrower to compensate for this.
The contact position of the V-belt 40 at 0 is closer to the drive shaft 1, and therefore, the movable pulley 14 is separated from the fixed pulley 13 in order to make the drive-side pulley 10 wider.

Therefore, in this state, the distance from the V-belt 40 abutting position to the central axis changes sequentially in both the driving and driven pulleys 10 and 20, and regardless of the change in the rotational speed of the driving pulley 10, The side pulley 20 always rotates at a constant rotation speed.

As the engine speed increases further, the driving pulley 10 becomes the widest and stops at that state, the driven pulley 20 becomes the narrowest and stops at that state, and from then on, the engine (driving pulley The rotation speed of the driven pulley 20 also increases in accordance with the rotation speed of the driven pulley 20. However, in this case, the distance from the central axis to the variable speed V-belt 40 is smaller at the driving pulley 10 and larger at the driven pulley 20, so the engine speed is transmitted to the driven pulley 20 at a constant reduction ratio. become.

As is clear from the above explanation, in the device of the present invention, the reduction ratio is controlled by the centrifugal force of the flyweight 28, and for this purpose, in order to operate the device of the present invention well, it is necessary to control the flyweight. The centrifugal force of 28 must be accurately transmitted to the movable pulley 24. In other words, holder 29
It is necessary to arrange them point-symmetrically around the driven shaft 21 so that the centrifugal force of the flyweight 28 can be distributed without eccentricity in the circumferential direction.

Therefore, in the device of the present invention, the movable pulley 24 is provided with the annular projection 24a as described above, the outer peripheral end 29b of the holder 29 is locked to the second flange surface 24b of the annular projection 24a, and the inner peripheral end 29c of the holder 29 is is also locked to the first flange surface 24c of the movable pulley 24. Moreover, in the device of the present invention, the first and second flange surfaces 24 of the movable pulley 24
c, 24b and the inner and outer peripheral edges 29 of the holder 29
c and 29b are both surfaces that coincide with the radial direction of the driven shaft 21, so that after the centrifugal force of the flyweight 28 is transmitted to the inclined surface 29 of the holder 29, it is transmitted through the first and second flange surfaces 24c and 24b. This means that the information is reliably and accurately transmitted to the movable pulley 24 side.

Moreover, the holder 29 is located in the groove 2 of the movable pulley 24.
Since it is designed to be fitted and fixed within 4d,
It is securely held and does not shift in the radial and circumferential directions no matter how much the movable pulley 24 rotates.

Next, the operation of the driven side cam mechanism 14 will be briefly explained.

When the load on the auxiliary equipment that is received via the V-belt 41 suddenly increases, a load corresponding to the load torque acts on the working surfaces 31a and 32a of both the fixed side and movable side cams 31 and 32 of the driven side cam mechanism 33. It's summery.
That is, in this case, as shown in FIG.
a, 32a are inclined with respect to the axial center of the driven shaft 21, so that the load component in the axial direction of the driven shaft 21 urges the driven pulley 20 in the wider direction to help the set load of the spring 27. It becomes power. Therefore, when the load on the auxiliary machine suddenly increases, the cam mechanism 3 acts to bias the spring 27, thereby reducing the change in the rotational speed of the driven pulley 20 due to the sudden change in load.

Although the above-described embodiments are desirable embodiments of the present invention, the present invention is not limited to this one embodiment, and various other embodiments are conceivable.

That is, in the above-described embodiment, the cam mechanisms 19, 33 and the flyweight 28 were made of materials with high self-lubricating properties, but if necessary, forced lubrication using lubricating oil such as grease may be provided. Good too. In addition to the above-mentioned materials, the holder 29 may also be made of a material with a small coefficient of wear such as carbon graphite.

Further, in the above example, the groove 24d allows the holder 2 to
However, for example, the inner circumference of the holder 29 is attached to the movable pulley 24 using a pin or the like.
A similar effect can be obtained by fixing it to the first flange surface 24c.

Further, in the above example, the fly weight 28 is provided on the driven pulley 20, but the fly weight 28 may be provided on the driving pulley 10 if necessary.

Furthermore, in the above embodiments, the device of the present invention was used for power transmission between an automobile engine and an auxiliary machine, but it goes without saying that the device of the present invention can be applied to other uses. Of course, if there is only one rotating machine to be connected, the V-groove 23a may be omitted and the rotation may be directly transmitted through the driven shaft 21.

As explained above, in the device of the present invention, the movable pulley is formed with first and second flange surfaces that coincide with the radial direction of the shaft and are shifted from each other in the axial direction of the shaft, and the inner and outer peripheral ends of the holder are also aligned with the shaft. Since the holder is fixed to the movable pulley with the inner and outer circumferential edges in close contact with the first and second flange surfaces as a plane that coincides with the radial direction, the holder can be held well and the holder can be received through the holder. This has an excellent effect in that the centrifugal force of the fly weight is reliably transmitted to the movable pulley side. At the same time, the centrifugal force of the flyweights is transmitted to the movable pulley via the inclined surface of this holder, making manufacturing easier as there is no need to directly form the inclined surface that requires precise dimensional accuracy on the movable pulley. Furthermore, while using a lightweight material for the pulley, only the holder can be made of a material with excellent strength and wear resistance, which also has the effect of reducing the weight and improving the durability of the device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention;
FIG. 2 is a front view of the main part of the flyweight section of the device shown in FIG. 1, and FIG. 3 is an exploded view showing the driven side cam mechanism of the device shown in FIG. 1... Drive shaft, 13, 23... Fixed pulley,
14, 24... Movable pulley, 21... Driven shaft,
25... Fixed plate, 28... Fly weight, 29
...Holder, 40...Belt.

Claims (1)

[Scope of Claims] 1. A belt is held between a fixed pulley that is fixed to a shaft and rotates integrally with the shaft, and a movable pulley that is arranged opposite to this fixed pulley and is movable in the axial direction of the shaft to transmit power. the movable pulley has first and second flange surfaces that are aligned with the radial direction of the shaft and spaced apart from each other in the axial direction of the shaft, on a surface of the movable pulley opposite to the contact surface with the belt; The holder has flat surfaces coinciding with the radial direction of the shaft at the inner and outer circumferential ends and an inclined surface at the intermediate portion, and the flat surfaces at the outer circumferential ends are in contact with the first and second flange surfaces, respectively. A fixed plate fixed to the movable pulley so as to be in contact with the movable pulley and configured not to move in the axial direction of the shaft is disposed so as to cover the holder, and an inclined surface of the fixed plate and the holder. A flyweight is disposed between the fixed plate and the inclined surface so as to contact both the fixed plate and the inclined surface at the same time, and when the pulley rotates, the centrifugal force generated in the flyweight is applied to the movable pulley via the inclined surface of the holder. A power transmission device characterized in that the movable pulley is biased in the axial direction of the shaft by transmitting a force to the movable pulley. 2. The power transmission according to claim 1, wherein the movable pulley is made of a relatively lightweight metal material, and the holder and the fixed plate are made of a metal material with high hardness and excellent wear resistance. Device. 3. The power transmission device according to claim 1 or 2, wherein the holder is made of a steel material whose inclined surface has been heat-treated or surface-treated to increase hardness.