JPS633187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power transmission device that transmits the rotation of a driving pulley to a driven pulley via a belt. The present invention relates to a power transmission device that is effective for transmitting power to auxiliary equipment such as an alternator and a power steering pump.

An object of the present invention is to provide the power transmission device with:
Rotation can be transmitted so that the rotation speed of the driven shaft is approximately constant when the rotation speed of the drive shaft is within a predetermined range. Another object of the present invention is to provide a device that can prevent belt slippage by increasing the pressing force against the belt at the driving pulley and the driven pulley.

Preferred embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the number 1 indicates a drive shaft, and the drive shaft 1 is a crankshaft of an automobile engine in this example, and its rotation direction is indicated by P. A drive-side pulley 10 is attached to the drive shaft 1, and the drive-side pulley 1
0 has a belt 40 wrapped around it. Also code 21
indicates a driven shaft, and the driven shaft 21 is supported on an engine block or the like by a bearing or the like (not shown).
A driven pulley 20 is attached to the driven shaft 21, and a belt 40 is similarly wound around the driven pulley 20. Therefore, by transmitting the rotation of the drive pulley 10 to the driven pulley 20 via the belt 40, the rotation of the drive shaft 1 is transmitted to the driven shaft 21.

The driving pulley 10 includes a fixed pulley 13 and a movable pulley 14, and the driven pulley 20 also includes a fixed pulley 23 and a movable pulley 24.
These fixed pulleys 13, 23 and movable pulleys 14, 24 are respectively connected to the drive shaft 1 and the driven shaft 21 in the manner described below.

First, the structure of the drive shaft pulley 10 will be explained. The main shaft 11 is integrally fixed to the drive shaft 1 with a bolt 15 and a key (not shown). It is screwed onto the main shaft 11, thereby being integrally fixed to the main shaft 11. A portion of the central inner surface of the fixed pulley 13 without the threaded portion 13a is fitted with the main shaft 11 to prevent the fixed pulley 13 from wobbling. The end 13b of the fixed pulley 13 comes into contact with the step 11a of the main shaft 11. By tightening the fixed pulley 13, the end 13b of the fixed pulley and the step 11a of the main shaft come into close contact, preventing water, mud, etc. prevents infiltration.

The main shaft 11 is also provided with a drive-side cam mechanism 19 that biases the movable pulley 14 toward the fixed pulley 13 in accordance with the magnitude of the load torque, that is, in the direction in which the drive-side pulley 10 becomes narrower. ing. The drive-side cam mechanism 19 consists of a fixed cam 17 and a movable cam 18. The fixed cam 17 is integrally fixed to the main shaft 11 by press fitting or the like, and the movable cam 18 is fixed to the main shaft 11 by a bolt 5.
2 is integrally fixed to the movable pulley 14. A dry bearing 12 is driven into the inner peripheral surface of the ring portion 18c of the movable cam 18, and the movable cam 18 and the movable pulley 14 are driven by the dry bearing 12.
At the same time, it can slide on the main shaft 11 in the axial direction. A spring 16 is disposed between the fixed cam 17 and the movable pulley 14, and the spring 16 causes the movable pulley 14 to move towards the fixed pulley 13 due to its initial setting load.
In other words, the drive pulley 10 is biased in a direction in which the width of the drive pulley 10 becomes narrower. Note that the movable pulley 14 is made of a relatively lightweight metal material such as aluminum alloy in order to reduce the weight of the device.

The fixed cam 17 and the movable cam 18 of the drive-side cam mechanism 19 each have operating surfaces 17a and 18a that are in constant contact with each other during power transmission. The working surfaces 17a, 18a are formed into straight lines as seen in the developed view of FIG. 2, and the angle α thereof is a calculated appropriate angle. With this structure, when a force is applied between the fixed cam 17 and the movable cam 18 in a direction that causes the working surfaces 17a, 18a to strongly contact each other due to changes in load, the working surfaces 17a, 18a
A thrust component in the axial direction is generated according to the angle of , and the movable cam 18 moves in a direction away from the fixed cam 17. Therefore, the movable pulley 14 integrally fixed to the movable cam 18 is pushed in a direction closer to the fixed pulley 13, and the width of the driving pulley 10 becomes narrower.

Reference numeral 54 denotes a timing plate for checking the ignition timing of the engine, which is integrally fixed to the fixed cam 17. Reference numeral 50 designates a first oil seal for sealing between the main shaft 11 and the movable pulley 14, and is assembled into a groove 54a integrally formed in the timing plate 54. and the first oil seal 50
The outer periphery of the movable pulley 14 is in sliding contact with the inner circumferential surface 51a of the ring 51 press-fitted into the inner circumferential surface 14a of the movable pulley 14 to prevent water, muddy water, and dust from entering into the driving pulley from the outside. The ring 51 is made of a material different from that of the movable pulley 14 and is made of a relatively hard metal, such as iron. 53 is a second oil seal for sealing between the fixed pulley 13 and the movable pulley 14;
It is assembled into a groove 14b integrally formed in the. Similarly to the first oil seal 50, the outer circumference of the second oil seal 53 is in sliding contact with the inner circumferential surface 13c of the fixed pulley 13 to prevent water, muddy water, and dust from entering from the outside into the drive-side pulley. There is.

Reference numerals 18b and 14c are ventilation holes provided in the movable cam 18 and the movable pulley 14 to prevent the pressure inside the drive pulley from increasing or decreasing due to a change in volume due to movement of the movable pulley. 13d and 14d are fixed pulleys 1
4 and a rib protruding from the surface of the movable pulley 13 opposite to the surface that contacts the belt 40,
A plurality of them are formed radially.

Next, the structure of the driven pulley 20 side will be explained. The fixed pulley 23 has a plurality of (in this example, four) together with the plate 37 and the ring seal 38.
The plate 37 is press-fitted onto the driven shaft 21. The fixed pulley 23 may be directly fixed to the driven shaft. This fixed pulley 23 has a plurality of V grooves 23.
a is engraved, and power is transmitted to automobile auxiliary equipment such as air pumps, water pumps, fans, compressors, alternators, power steering pumps, etc. via a poly V-belt 41 having a plurality of V-shaped ribs. ing.

Similarly to the driving pulley 10, the driven shaft 21 is also provided with a shaft that moves the movable pulley 24 closer to the fixed pulley 23 depending on the magnitude of the load torque, that is, in the direction that the driven pulley 20 becomes narrower. A driven side cam mechanism 33 for urging is provided. The driven side cam mechanism 33 consists of a fixed cam 31 and a movable cam 32, and the fixed cam 31 is connected to the driven shaft 2.
The movable cam 32 is integrally fixed with a bolt 61 to a fixed plate 25 which is press-fitted into the fixed plate 25.
is integrally fixed to the movable pulley 24 with bolts 60. A dry bearing 22 is driven into the inner peripheral surface of the ring portion 32b of the movable cam 32, and the dry bearing 22 causes the movable cam 32 and the movable pulley 24 to move along the driven shaft 21 in the axial direction together with the dry bearing 22. It is designed to be able to glide.

A spring 27 is disposed between the fixed pulley 23 and the movable pulley 24, and the initial setting load of this spring causes the movable pulley 24 to
The driven pulley 20 is biased in a direction away from the fixed pulley 23, that is, in a direction in which the driven pulley 20 becomes wider.

Note that the movable pulley 24 is similar to the drive pulley 10.
Similar to the above, it is made of a relatively lightweight metal material such as aluminum alloy in order to reduce the weight of the device and facilitate its movement.

The fixed cam 31 and the movable cam 32 of the driven side cam mechanism 33 have working surfaces 31a and 32a, respectively, which are in constant contact with each other during power transmission, as in the driving side cam mechanism 19.
is formed in a straight line as shown in the developed view of FIG. 4, and its angle β is a calculated appropriate angle. With this structure, when a force is applied between the fixed cam 31 and the movable cam 32 in a direction that causes the working surfaces 31a, 32a to strongly contact each other due to fluctuations in load torque, the axis of the working surfaces 31a, 32a changes depending on the angle of the working surfaces 31a, 32a. A thrust component in the direction is generated, and the movable cam 32
moves in a direction away from the fixed cam 31. Therefore, the movable pulley 2 is integrally fixed to the movable cam 32.
4 is pushed in the direction closer to the fixed pulley 23, and the driven pulley 20 becomes narrower.

A flyweight 28 is also disposed on the side of the driven pulley 20, which urges the driven pulley 20 in a direction in which the width thereof becomes narrower by centrifugal force accompanying the rotation of the driven pulley. fly weight 2
0 has a roller shape, and as shown in FIG. 4, a plurality of rollers are housed in a space formed by a holder 29 having an inclined surface 29a and a fixing plate 25. In this example, four holders 29 for storing two flyweights 20 are provided, and a total of eight flyweights are arranged. Each holder 29 is fixed to the movable pulley 24 with a pin 30. Here, a plurality of oil grooves 2 are provided on the outer periphery of the flyweight 28.
8a (two in this example) are installed to reliably hold lubricating oil filled near the outer periphery of the flyweight 28 for lubrication. Further, the holder 29 is formed with a holding surface 29b that is continuous with the inclined surface 29a and parallel to the driven shaft 21, so that when the flyweight 28 moves to the outermost radial direction due to centrifugal force, the apex of the flyweight 28 is It comes into contact with this holding surface 29b. Further, a flange 29d is formed on the side of the holder 29 to support movement of the flyweight.

A cover 35 covers the outer surface of the fixed plate 25, and is fixed to the outer peripheral surface of the movable pulley 24 with machine screws 62. Further, an O-ring groove is provided on the outer peripheral surface of the movable pulley 24, and an O-ring 36 inserted into this groove connects the flyweight 28 and the holder 29, and the flyweight 28 and the fixed plate 2.
This prevents the lubricating oil filled between the holes 5 and 5 from scattering to the outside. Further, reference numerals 24b and 25a are ventilation holes provided in the movable pulley 24 and the fixed plate 25 to prevent pressure from increasing and decreasing due to a volume change inside the driven pulley as the movable pulley 24 moves. A plurality of ribs 23b are formed in a radial manner and project from the surface of the fixed pulley 23 opposite to the surface that contacts the belt 40. Reference numeral 63 denotes an oil seal for sealing between the movable pulley 24 and the fixed pulley 23, and is assembled into a groove 24c integrally formed on the movable pulley 24. The inner periphery of the oil seal 63 is in sliding contact with the outer periphery 38a of the seal ring 38 which is integrally fixed to the fixed pulley 23.
Water, mud, dust, etc. are prevented from entering the driven pulley from the outside. The variable speed V-belt 40 is suspended between the driving pulley 10 and the driven pulley 20 and transmits the rotation of the driving pulley 10 to the driven pulley 20, and is made of rubber with a strong core.

Next, the operation of the power transmission device having the above structure will be explained. As the engine speed increases from an idling state, the driving side pulley 10 and the driven side pulley 20 also increase the speed, and as a result, the centrifugal force of the flyweight 28 increases and acts on the inclined surface 29a of the holder 29. Holder 29
The component of the force that presses the movable pulley 24 toward the stationary pulley 23 via the force increases. Then, due to the centrifugal force of this flyweight 28, the movable pulley 24
The force acting to move the springs 16, 27
In a range smaller than the force proportional to the total load, the movable pulley 24 does not move in the axial direction, the rotation transmission ratio between the driving pulley 10 and the driven pulley 20 does not change, and transmission is performed at a predetermined constant ratio. It is done.

Next, the engine speed increases further, and the force acting to move the movable pulley 24 due to the centrifugal force of the flyweight 28 is increased by the springs 16 and 2.
7, the movable pulley 24 moves toward the fixed pulley 23, and as a result, the driven pulley 20 becomes narrower, and the V-belt 40
The contact area of the V-belt 40 moves away from the driven shaft 21 (the pulley effective diameter becomes larger), and the contact position of the V-belt 40 on the drive side pulley 10 approaches the main shaft 11 to compensate for this (the pulley effective diameter becomes smaller). ), therefore, in order to make the drive side pulley 10 wider, the movable pulley 14 is wider than the fixed pulley 1.
It will be further away than 3. Therefore, in this state, the distance from the abutting position of the V-belt 40 to the central axis changes sequentially in both the driving and driven pulleys 10 and 20, so that rotation transmission between the driving and driven pulleys 10 and 20 is reduced. The ratio becomes smaller, and the driven pulley 20 always has a constant rotation speed regardless of the increase in the rotation speed of the driving pulley 10.

As the engine speed increases further, the driving pulley 10 eventually becomes the widest and stops there, the driven pulley 20 becomes the narrowest and stops, 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 speed change V-belt 40 is small at the drive side pulley 10, and the distance from the driven side pulley 2 is small.
Since the rotation speed of the engine is large at 0, the engine speed is transmitted to the driven pulley 20 even at a constant reduction ratio.

Next, the cam mechanisms 19 and 33 on the drive side and the driven side
The operation of this will be explained.

When the load on the auxiliary equipment received via the poly V belt changes suddenly, such as when the compressor suddenly starts operating, or when the load on other auxiliary equipment such as the power steering pump is large, the driven side cam mechanism 33 A load torque acts on the fixed cam 31 to stop its rotation, and depending on the magnitude of the load torque, the working surfaces of both the fixed and movable cams 31 and 32 that are in contact with each other are affected as described above. 31a and 32a try to make stronger contact. Then, a thrust component in the axial direction corresponding to the angle β of the working surfaces 31a and 32a is generated, and this force is used to assist the force acting to move the movable pulley 24 toward the fixed pulley 23 due to the centrifugal force of the flyweight 28. , biases the driven pulley 20 in the direction of narrowing the width. Therefore, when the load on the auxiliary machine suddenly changes or is very large, the cam mechanism 33 increases the force of the driven pulley 20 that presses the belt, thereby preventing the belt from slipping due to a sudden change or very large load. In addition, the driven side cam mechanism 33, through the above-described operation, significantly reduces changes in the rotational speed of the driven pulley 20 due to sudden changes in load or changes in load between low and high loads.

Similarly, sudden changes in the load of auxiliary equipment or extremely large loads may be applied to the drive pulley 10 via the V-belt 40.
, a load torque acts on the movable cam 18 of the drive side cam mechanism 19 to stop its rotation, and as described above, depending on the magnitude of the load torque, both the fixed and movable cams 17 , 18, which are in contact with each other, try to contact each other more strongly, and the working surfaces 17a, 32a
A thrust component in the axial direction corresponding to α is generated, and this force pushes the movable pulley 14 in a direction closer to the fixed pulley 13, making the driving pulley 10 narrower. Therefore, the cam mechanism 19 increases the force with which the drive pulley 10 presses the belt, thereby preventing slippage due to sudden changes in load or extremely large loads. Further, through the above-described operation, the drive-side cam mechanism 19 significantly reduces changes in the rotational speed of the drive-side pulley 10 due to sudden changes in load or changes in load between low and high loads.

Figure 5 shows the change in the rotational speed of the driven pulley 20 when the driving pulley 10 is accelerated (indicated by a in the figure) or decelerated (indicated by b in the figure). The figure shows the state when a load torque of 2 kgm is suddenly applied at the drive side rotation speed at point c during deceleration. Here, the solid line shows the cam mechanism of the present invention on the drive side and the driven side. Especially during deceleration, even if a load is suddenly applied at point C, the rotation speed of the driven side pulley 20 will only slightly fluctuate. It can be seen that the belt 40 hardly slips. On the other hand, the broken line does not have a cam mechanism, but is equipped with a general mechanism such as a linear spline for transmitting torque, and the number of rotations of the driven pulley 20 at point C where a sudden load is applied especially during deceleration. It can be seen that the belt 40 is slipping. From the above results, it can be seen that the belt provided with the driving side and driven side cam mechanisms 19, 33 of the present invention does not cause belt slip and can operate stably.

Next, FIG. 6 shows a device equipped with the cam mechanisms 19 and 33 of the present invention (indicated by solid lines in the figure), and a device not equipped with a cam mechanism but with an increased initial setting load for the springs 16 and 27 (indicated by solid lines in the figure). Figure 6 shows the change in the rotational speed of the driven pulley 20 as the load changes with respect to the load (indicated by the broken line). It can be seen that in all cases (indicated by B in the figure), the one equipped with the cam mechanism of the present invention is much improved.

Furthermore, the fly weight 2 of the driven pulley 20
The functions of 8 and holder 29 will be explained.
When the fly weight 28 is at the outermost position, that is, when the engine (drive side pulley 10) is rotating at high speed,
When the driven pulley 20 is at its narrowest width,
The apex portion of the fly weight 28 comes into contact with the holding surface 29b of the holder 29 and is held in that state. Therefore, in this state, the force that the movable pulley 24 pushes the speed change belt 40 in the axial direction is only a force that corresponds to the load of the auxiliary equipment, regardless of the rotation of the engine (drive side pulley 10). It can be the same as a pulley. As a result, unnecessary large axial force is not applied to the belt 40, and the durability of the V-belt 40 can be greatly improved.

Furthermore, a predetermined amount of lubricating oil is sealed in the sliding surfaces between the flyweight 28 and the holder 29 and between the flyweight 28 and the fixed plate 25, and this lubricating oil is provided around the outer periphery of the flyweight 28. Since it is reliably held by the oil groove 28a, the flyweight 28 can slide smoothly without seizing on the sliding surface.

In the above embodiment, the driven side cam mechanism 33 was provided between the movable pulley 24 and the fixed plate 25, but the fixed cam 31 may be placed at any position as long as it is not movable in the axial direction. A configuration may also be used. Further, the driven side cam mechanism may be arranged as shown in FIG. That is, a fixed cam 70 in FIG. 7 is integrally fixed to the driven shaft 21 by a method such as press fitting, and is fixed together with the seal ring 38 and the fixed pulley 23 by bolts 39. On the other hand, the movable cam 72 is integrally fixed to the movable pulley 24 with bolts 74, and the two cams 70 and 72 are respectively provided with working surfaces 70a and 72a having the same angle, as shown in the exploded view of FIG. , the fixed cam 70 and the movable cam 72 form a driven cam mechanism 68. In the above example, the fixed cam 70 is integrally fixed to the driven shaft 21 by press-fitting, but the fixed cam 70 may be provided at any position as long as it does not move in the axial direction, for example, on the fixed pulley 23. In the above description, the arrangement position of the driven side cam mechanism has been described, but the same applies to the driving side cam mechanism 19. Furthermore, although the description has been made regarding the case where the spring 27 is provided on the driven side, the above-mentioned operating performance can be obtained even without the spring 27, although the responsiveness during deceleration is somewhat inferior.

Furthermore, in the above-described embodiment, the fixed cams 31 and 70 are fixed to the fixed pulley 23 with bolts, etc., but they may also be fixed by press fitting, keys, or pins, or they may be integrally cast with the same material as the fixed pulley 23 or made of a different material. It may also be cast with an insert.

Also, to explain the movable cams 32 and 72,
In the above-mentioned embodiment, the movable cams 32, 72 were fixed by driving the dry bearings 22 into their inner peripheral surfaces, but as shown in FIG. It is also possible to mold the ring 76b and slide it directly on the driven shaft on the inner peripheral surface of the ring 76b. Furthermore, metal may be inserted only in the screw hole portion 76c. This eliminates the need for dry bearings in the movable cam, resulting in a lightweight and inexpensive structure.

Alternatively, as shown in FIG. 10, only the sliding portion that provides the working surface may be bonded with resin such as carbon fiber, or may be outsert molded onto a base material such as metal. That is, in FIG. 10, 80 is a cam base material having a groove 80a, and a resin chip 81 is inserted into the groove 80a.
are assembled by adhesive or molding. The tip 81 has a working surface 81a and is adapted to come into contact with the working surface of the mating fixed cam 31. Further, the dry bearing 22 is driven into the inner peripheral surface of the cam base material 80, but similarly to the case of the chip 81, the dry bearing 22 may be made of the same material as the chip 81 or a different material and fixed by molding. . This allows the movable cam to have a lightweight and inexpensive structure.

Further, in the above example, the movable cams 32, 72 are fixed to the movable pulley 24 by bolts or the like, but they may be press-fitted or fixed by keys, pins, etc. In the above description, the movable cam 32 on the driven side has been described, but it goes without saying that the invention can also be applied to the movable cam 18 on the driving side.

Further, in the above example, the flyweight 28 is provided on the driven pulley 20, but it may be provided on the driving pulley 10 if necessary. Furthermore,
In the embodiments described above, the device of the present invention was used as a power transmission device between the engine and auxiliary equipment of an automobile, but it goes without saying that the device of the present invention can be used for other purposes.

As described above, in the device of the present invention, the drive side cam mechanism and the driven side cam mechanism bias the drive side and driven side pulleys in the narrow direction according to the load torque of the auxiliary equipment. The belt does not slip even when there are sudden fluctuations in speed or when a very large load is applied.As a result, the load torque can be transmitted reliably, there is no slipping noise, and the durability of the belt is greatly improved. This has the excellent effect of improving fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the power transmission device of the present invention, FIG. 2 is an exploded view of a fixed cam and a movable cam of the drive side cam mechanism in the device shown in FIG. 1, and FIG. FIG. 1 is a developed view of the fixed cam and movable cam of the driven cam mechanism in the device shown in FIG. 6 is a graph showing the test results of the device shown in FIG. 1, FIG. 7 is a sectional view showing another embodiment of the driven side cam mechanism, and FIG. 8 is a graph showing the driven side shown in FIG. 7. A developed view of the fixed cam and the movable cam of the cam mechanism, and FIGS. 9 and 10 are perspective views showing other embodiments of the movable cam. In the figure, 1...drive shaft, 10...drive side pulley, 1
DESCRIPTION OF SYMBOLS 1... Main shaft, 13... Fixed pulley, 14... Movable pulley, 17... Fixed cam, 18... Movable cam, 19...
Drive side cam mechanism, 20... Driven side pulley, 21...
Driven shaft, 22...Dry bearing, 23...Fixed pulley, 24...Movable pulley, 25...Fixed plate, 2
5a... Inclined surface, 27... Spring, 28... Fly weight, 29... Holder, 29a... Inclined surface, 2
9b... Holding surface, 31... Fixed cam, 32... Movable cam, 33... Driven side cam mechanism.

Claims (1)

[Scope of Claims] 1. A power transmission device that transmits the rotation of a driving pulley to a driven pulley via a belt, which comprises: a fixed pulley that rotates the driving pulley integrally with a drive shaft; and a fixed pulley that is arranged opposite to the fixed pulley. and a movable pulley that is movable in the axial direction of the drive shaft, and a spring is arranged to bias the drive pulley in the direction of narrowing the width, and the driven pulley is fixed to rotate integrally with the driven shaft. It is formed by a pulley and a movable pulley that is arranged opposite to the fixed pulley and is movable in the axial direction of the driven shaft, and is provided with a spring that biases the driven pulley in a direction to make it wider, and
A flyweight is disposed that biases the driven pulley in the direction of narrowing the width by centrifugal force accompanying the rotation of the driven pulley, and the driving pulley is applied with a flyweight according to the magnitude of the load torque. A driving side cam mechanism is provided for biasing the driving side pulley in the narrow width direction according to the magnitude of the load torque, and a driven side cam mechanism is provided for the driven side pulley for biasing the driven side pulley in the narrow width direction according to the magnitude of the load torque. A power transmission device characterized by: 2. The driving side and driven side cam mechanisms are constituted by a fixed cam and a movable cam, the fixed cam is integrally fixed to a portion that does not move in the axial direction, and the movable cam is integrally fixed to the movable pulley. The power transmission device described in section. 3. The power transmission according to claim 2, wherein the movable cam is integrally molded with a resin reinforced with carbon fiber or the like, and is directly engaged with the driving shaft or the driven shaft so as to be slidable in the axial direction. Device.