JPH02203052A - Belt transmission device having automatic tension adjusting mechanism - Google Patents

Abstract

PURPOSE:To reduce arranging space and weight further enabling reduction to be attained of friction torque less, noise and wearing by continuously decreasing an eccentric amount of the second pulley member from the first pulley member following an increase of driving force of the first pulley member. CONSTITUTION:When a device is placed in a loaded condition by applying a load to a driven pulley 11 and drive power to a drive pulley 3, the first pulley member 4 is rotated in a direction equal to the drive power relatively to the second pulley member 5, and a flexible member 10 changes a direction of its span in a circumferential direction. Consequently, the drive power is transmitted from the pulley member 4 to the pulley member 5 through the first pulley side pins 8, 8..., member 10 and the second pulley side pins 9, 9.... Simultaneously, the pulley member 5 moves along a plane p, passing through axial centers O1, O2 of both the pulley members 4, 5, to a belt tightened side so as to decrease an eccentric amount of the pulley member 4, and following the above, a timing belt B distributes to its tightened side and loosened side always fixed tension. As the result, skip reduction can be suppressed of the timing belt B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a belt transmission device that automatically adjusts the tension of a timing belt according to driving force to suppress the skip phenomenon. .

(Prior art) Conventionally, in belt transmission devices that perform belt transmission by winding a timing belt (synchronous belt) around a toothed pulley, when the belt tension decreases, the contact between the teeth of the belt and the peaks of the pulley increases. There is a problem in that meshing is lost and a so-called skip phenomenon occurs.

As a device for suppressing such a skip phenomenon, a tension mechanism is conventionally known in which a tension roller biased by a spring or the like presses the back surface of the slack side of the belt to apply tension to the belt according to the driving force. . However, in this case, since the belt is bent by the tension roller in the back direction opposite to the normal bending direction, fatigue of the belt center body is accelerated and the durability of the belt is reduced. In addition, if a large torque is applied or if the belt stretches over time, the tension roller's spring returns and the pressing force decreases, making it possible to reliably prevent the skip phenomenon from occurring. do not have.

Therefore, in order to eliminate the above-mentioned problems, the
A belt transmission device equipped with an automatic tension adjustment mechanism disclosed in Japanese Patent No. 47592 has been proposed.

That is, in this proposal, for example, as shown in FIG. 4, a pair of mutually parallel rotation axes a, b, etc.
Driving and driven pulleys e and d each consisting of a toothed pulley are supported by the pulleys c and d, and a timing belt e is provided which is wound between the pulleys c and d and transmits power between the rotating shafts a and b. , one of the driving or driven pulleys c, d is connected to a first pulley member g which is rotationally integrally supported by the rotating shafts a and b and has a gear f on the outer periphery, and a first pulley member g on the outer periphery of the first pulley member g. The gear f of the first pulley member g is arranged eccentrically with respect to the axis a1 of the first pulley member g.
a second pulley member j having a gear h on its inner periphery that meshes with the timing belt e, and a second pulley member j having teeth i on its outer periphery that mesh with the timing belt e;

A straight line 2A connecting the axes al+bl of b and the straight line 9A
The axis i1 of the second pulley member i is located eccentrically by a predetermined amount in a slack side 1-center zone Z defined by a straight line IHe that is perpendicular to the line IHe and passes through the axis a1 of the first pulley member g. , the length of the belt e is set.

(Problem to be Solved by the Invention) However, in this proposal, when the driving pulley C side is composed of the first and second pulley members g11 as shown in the figure, the diameters of the two pulley members g and i are different. Therefore, the number of gears h on the second pulley member i side is necessarily ′! The number is greater than the number of gears f of the B1 pulley member g, and the rotation of the rotating shaft a is decelerated to reach the second pulley member 1, that is, the belt et:i. Therefore, from the driving pulley C to the driven pulley d
When applied to a bicycle drive system that needs to transmit l'JiD rotation at an increased speed, the diameter of the drive pulley C must be made larger than necessary in anticipation of the above deceleration in order to ensure the increased speed transmission. This may cause the installation space to become larger, or
There are problems such as an increase in weight.

Also, both pulley members g and i are rigid bodies with one tooth 'l! Since l'1lTh, all of the driving force is concentrated on one tooth, which increases torque loss and noise due to friction during meshing, and there are also problems such as reduced durability due to wear.

Moreover, if foreign matter gets into the gears 1 and 6 of both pulley members g and L, there is a risk that the pulleys will be damaged.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a belt transmission device in which a first pulley member coupled and supported by a rotating shaft and a second pulley member meshingly connected to a belt are connected to a gear. By connecting the first pulley member at multiple points instead of at one point on the circumference using a predetermined means other than a mechanism, the rotation of the first pulley member remains unchanged without deceleration, and concentration of driving force is avoided. This drive system is capable of transmitting torque while reducing torque loss, noise, wear, etc., and also eliminates the adverse effects of foreign matter contamination, and increases the rotation speed of the drive side pulley and transmits it to the driven side pulley. Another objective is to keep the diameter of the pulley on the drive side small, thereby reducing the installation space and weight.

(Means for Solving the Problems) In order to achieve this object, the solution means of the present invention is to replace the first and second pulley members of the drive-side pulley with endless high-tensile flexible members. Concatenate using .

Specifically, in the invention described in claim (1), a pair of rotating shafts parallel to each other, a driving and driven pulley consisting of a toothed pulley respectively supported by the rotating shafts, and a winding between the two pulleys are provided. For a belt transmission device equipped with a timing belt that is hung and transmits power between both rotating shafts, the drive pulley has the following configuration.

That is, the drive pulley includes a first pulley member rotatably supported by the rotating shaft, and a first pulley member on the outer periphery of the first pulley member.
a second pulley member that is arranged eccentrically with respect to the axis of the pulley member and has a peak on its outer periphery that engages with the timing belt; A plurality of first pulley side pins and a plurality of first pulley side pins are arranged on a concentric circle having a diameter larger than the diameter within the arrangement of the plurality of first pulley side pins on the side surface of the second pulley member at an angle equal to the arrangement angle of the first pulley side pins. The endless high tension rods are protruded at angular intervals, and are applied to second pulley side pins of the same number as the first pulley side pins, and to each of the first and second pulley side pins alternately and over the entire circumference. A flexible member.

The endless high-tensile strength flexible member is set to a length that allows loosening when both the pulley members are in a concentric position.

In addition, in the invention described in claim (2), specific examples of the endless high-tensile strength flexible member include a flat belt made of an elastic body with high-tensile threads embedded, an endless film made of metal or synthetic resin, or an endless film made of metal or synthetic resin. The rope is twisted into a shape.

Furthermore, in the invention described in claim (3), a rotatable sliding bearing is provided on each of the first and second pulley side pins for the purpose of reducing torque loss.

Further, in the invention described in claim (4), the first and second
In order to suppress displacement of the pulley members, one of the pulley members is provided with a flange that receives the other member and restricts relative movement in the axial direction between the two.

(effect) With the above configuration, the invention according to claim 11.

When a timing belt is wound between the driving and driven pulleys, the axial center of the second pulley is on the driven pulley side with respect to the axial center of the first pulley member due to the bending rigidity of the belt and the weight of the 21st pulley member. And the belt is eccentric to the slack side. The length of the endless high-tensile flexible member is set such that slack occurs when both pulley members are concentric, so that as the second pulley member becomes eccentric, the belt slack decreases. becomes zero. At this time, the eccentricity of the second pulley member is stopped by the flexible member. That is, in the no-load state, the second pulley member is at its maximum amount (-centered).

In this state, when a load is applied to the driven pulley and a driving force is placed on the driving pulley, when the driving force acts on the first pulley member, the driving force is distributed to the plurality of first pulley side pins of the first pulley member. is then transmitted from that pin to a second pulley-side pin via a high-tensile flexible member. In the unloaded state where the second pulley member is eccentric by the maximum amount, the span of the flexible member is approximately oriented in the axial direction, whereas the driving force is generated in the circumferential direction with respect to the axial center. In order to transmit the driving force, the first pulley member rotates in the same direction as the direction of the driving force with respect to the second pulley part.

Due to this rotation, the relative angle between the first pulley member and the second pulley member shifts, the span of the flexible member changes from the axial direction to the circumferential direction, and the driving force is transmitted through the plurality of second pulley side pins. and is transmitted to the second pulley member. At this time, since the length of the flexible member is constant, the axis of the second pulley member moves toward the axis of the first pulley member due to the relative rotation of the first pulley member with respect to the second pulley member. In this way, the second pulley member receives the driving force from the first pulley member and moves along a plane passing through the axes of both pulley members,
This movement increases the pitch circumference of the timing belt. Here, when a larger load is applied to the driven pulley and a larger driving force is applied to the driving pulley, the span of the flexible member needs to be oriented in the circumferential direction according to the driving force. The relative angle change between both pulley members further increases, and the axis of the second pulley member approaches the axis of the first pulley member. In this way, the amount of eccentricity of the second pulley member relative to the first pulley member changes depending on the magnitude of the driving force, so the tension side and slack side of the timing belt are adjusted at a constant ratio depending on the magnitude of the driving force. The tension can be distributed, and the belt skipping phenomenon can therefore be suppressed.

In that case, since both pulley members are connected by one endless high-tensile flexible member, the rotation of the rotation shaft can be transmitted to the drive pulley at a transmission ratio of 1=1, and the rotation of the drive pulley can be transmitted to the drive pulley at a transmission ratio of 1=1. Even when the speed is increased and the power is transmitted to the driven pulley, the drive pulley does not need to be made larger than necessary, so the space for disposing the drive pulley can be reduced and its QQ can be reduced.

In addition, as mentioned above, since the driving force is transmitted almost equally across the spans of multiple pins and flexible members, the friction Torque loss and noise are low, wear is suppressed and durability is improved, and the pulley members are not easily damaged even if foreign matter gets mixed in between the pulley members.

In the invention according to claim 2, the high-tensile flexible member is a flat belt made of a high-tensile thread embedded in an elastic body, an endless film made of metal or synthetic resin, or an endlessly twisted rope. Therefore, it is possible to satisfactorily satisfy the function of transmitting the driving force from the first pulley member to the second pulley member and the function of relatively displacing the axes of both pulley members.

Furthermore, in the invention described in claim (3), since the first and second pulley side pins are each provided with a rotatable sliding bearing, the torque loss is further reduced and the driving force transmission efficiency is further increased. At the same time, wear can be suppressed and durability can be further improved.

Furthermore, in the invention set forth in claim (4), since one of the first and second pulley members is provided with a flange that receives the other and restricts the relative movement of both in the axial direction, both pulley members can move in the axial direction. It is possible to prevent the pulley members from shifting relative to each other, and it is possible to reliably maintain the appropriate arrangement positions of both pulley members.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 and 2 show an embodiment in which the present invention is applied to a bicycle drive system, in which 1 is a drive shaft rotatably supported on a bicycle frame (not shown), 2 is the drive shaft 1 and A driven shaft is arranged in parallel and rotatably supported by a frame, and a crank pedal (not shown) is connected to the drive shaft 1. On the other hand, the driven shaft 2 supports a rear wheel (not shown) of the bicycle.

A drive pulley 3 with a ridge is attached to the drive shaft 1 so as to rotate integrally therewith. Further, a driven pulley 11 having a smaller diameter than the driving pulley 3 and having teeth 11a on the outer periphery is rotatably supported on the driven shaft 2, and the second driven pulley 11 and the rear wheel are connected in the driving rotation direction by a one-way clutch mechanism (not shown). In both figures, they are connected to rotate integrally only in the counterclockwise one-turn direction). A timing belt B is wound between the pulleys 3 and 11 and has a toothed portion B1 on the bottom surface (inner peripheral surface), and this belt B transmits power from the drive shaft to the driven shaft 2. It is done like this.

The drive pulley 3 includes a substantially disc-shaped first pulley member 4 that is rotatably supported by the drive shaft 1, and a first pulley member 4 that is rotatably supported by the drive shaft 1.
The main component is a substantially disc-shaped second pulley member 5 disposed on the outer periphery of the second pulley member 5 with respect to the axis 01 of the first pulley member 4 (-atrial function).

On the side surface of the first pulley member 4 facing the second pulley member 5, there are six first pulley side pins 8, 8. ... are provided protrudingly on the circumference centered on the axis 01 of the first pulley member 4 at equal angular intervals of 60''.

On the other hand, the second pulley member 5 includes a disc-shaped side plate 6 in which a center hole 6a having an inner diameter larger than the outer diameter of the first pulley member 4 opens, and a pulley portion integrally fixed to the outer periphery of the side plate 6. 7
A southern portion 7a that engages with the timing belt B is formed on the outer periphery of the pulley portion 7. Then, on the side surface of the side plate 6 facing the first pulley member 4, the plurality of first pulley side pins 8, 8. On the concentric circumference with a diameter larger than the diameter of the arrangement opening, there are the same number (six) of second pulley side pins 9゜9 as the number of first pulley side pins 8゜8゜.・is the first pulley side pin 8.8. They are protruded at equal angular intervals of 60 degrees, which is the same as the arrangement angle of ....

Further, the first pulley side pins 8, 8. ...and the second
Pulley side pin 9, 9. . . . One endless high-tensile strength flexible member 10 is attached to each pin 8, 9 alternately and over the entire circumference, and this endless high-tensile strength flexible member 10 The length (circumferential length) of is set to a length at which a predetermined loosening occurs when both pulley members 4.5 are in a concentric position, in order to enable eccentricity of both pulley members 4.5. .

The flexible member 10 is made of a flat belt, a film, or a rope. For example, the flat belt is made of an elastic material such as rubber or polyurethane in which high-tensile threads such as steel cables, aramid fibers, and glass fibers are embedded. Further, when a film is used, it is an endless film of metal, synthetic resin, etc. formed into an endless shape. Further, in the case of a rope, an endlessly twisted steel cable or a rope made of aramid fiber is preferable.

It is also defined by a straight line 9A connecting the axes 01 and 03 of the drive and driven shafts 1 and 2, and a straight line 9B that is orthogonal to the straight line 9A and passes through the axis 01 of the first pulley member 4. The length of the timing belt B is set so that the axis 0 of the second pulley member 5 is located eccentrically by a predetermined amount in the slack side eccentric zone 2.

Note that the number of each of the pins 8.9 may be increased or decreased to a plurality of pins other than the six in the illustrated row.

Therefore, in the above embodiment, both pulleys 3.11
In a no-load state where no power is transmitted between the two, the tension of the timing belt B becomes zero, as shown in FIG.
The maximum amount (-centered) with respect to the pulley axis 01.

From this state, when a load is applied to the driven pulley 11 and a driving force is applied to the driving pulley 3, resulting in a loaded state, the first pulley member 4 is driven relative to the second pulley member 5, as shown in FIG. The flexible member 1 rotates in the same direction as the direction of the force.
The direction of the 0 span changes in the circumferential direction. Therefore, the driving force is transferred from the first pulley member 4 to the first pulley side pin 8,
8. ...Flexible member 10 and second pulley side pin 9.9
．． ... is transmitted to the second pulley member 5. At the same time, the second pulley member 5 is moved to the axis 0 of both pulley members 4.5.
1.02, the timing belt B moves toward the belt tension side (in the direction of increasing the pitch circumference of belt B) so that the amount of eccentricity with respect to the first pulley member 4 decreases. A constant tension is always distributed between the tension side and the slack side. As a result, the decrease in skips in the timing belt B can be suppressed.

When the timing belt B is in the same state, the axes 01 and 0 of the two pulley members 4.5 substantially coincide with each other, thereby allowing the drive pulley 3 to rotate smoothly.

In this case, since both the pulley members 4 and 5 are connected by the endless high-tensile flexible member 10, the rotation of the drive shaft 1 can be transmitted to the drive pulley 3 at a transmission ratio of 1:1. Even when the rotation speed of the drive pulley 3 is increased and transmitted to the driven pulley 11, the drive pulley 3 does not need to be made larger than necessary, thereby reducing the installation space of the drive pulley 3 and its weight. be able to.

Further, the driving force is applied to a plurality of pins 8, 8. ...and 9゜9,
. . . and the plurality of pins 8, 8° . . . and 9, 9 . ... transmits 1/6 of the driving force, and each span of the flexible member 10 transmits 1/12 of the driving force. Therefore, compared to transmission by gear meshing where the driving force is concentrated on one tooth, frictional torque loss and noise can be suppressed to a low level, there is less wear, and durability can be improved, and foreign matter can get in between both pulley members 4 and 5. Even if this happens, it is possible to prevent the pulley members 4 and 5 from being damaged.

Further, as shown in FIG. 1, the tension of the timing belt B is zero in the no-load state, so the timing belt B
There is no need to apply initial tension when installing the tube, and the tube can be easily installed. What's more, the torque loss at startup is low, making it possible to reduce the force required to pedal the bicycle.

FIG. 3 shows another embodiment of the invention. Incidentally, the same parts as those corresponding to the first embodiment are given the same reference numerals, and detailed explanation thereof will be omitted.

In this embodiment, a flange 12 having a center hole 12g having a smaller diameter than the outer diameter of the first pulley member 4 is provided on the outer peripheral edge of the side surface of the second pulley member 5 on the side of the first pulley member 4 in the drive pulley 3'. It is arranged concentrically with the pulley member 5 and joined together. With this structure, both pulley members 4, 5
Even when the flange 12 and the second pulley member 5 are eccentric,
The ff1l pulley member 4 is eccentrically received between the side plate 6 of the pulley member 4, and the relative movement of both pulley members 4.5 in the axial direction is restricted. Furthermore, a rotatable sliding bearing 13 is attached to each of the first and second pulley side pins 8 and 9.

In the figure, reference numeral 14 denotes a bicycle frame that rotatably supports the drive shaft 1 and the driven shaft 2 (the support structure for the driven shaft 2 with respect to the frame 1 is not shown).

Further, at one end of the drive shaft 1, there is formed a mounting part 1a having a rectangular cross-section and a threaded part 1b formed at the tip of the mounting part 1a, which is formed by cutting parallel to each other diametrically opposing parts of the outer circumferential surface, and a threaded part 1b is formed at the tip of the mounting part 1a. The arm 15 is attached to the mounting portion 1a together with the first pulley member 4.
It is attached to the screw portion 1b and is screwed together to rotate integrally.

Therefore, in the case of this embodiment, since the flange 12 prevents the pulley members 4.5 from shifting in the axial direction, the pulley members 4.5, even though they are connected by the flexible member 10, There is an advantage in that it is possible to stably hold the .degree. 5 at a proper placement position.

In addition, since each pin 8, 9 is provided with a freely rotatable sliding bearing 13, the frictional resistance between each pin 8, 9 and the flexible member 10 is reduced, which further reduces torque loss and provides a smooth Not only can rotation be obtained, but also wear can be reduced and durability can be improved.

In each of the above embodiments, the present invention is applied to a bicycle drive system, but the present invention can also be applied to various belt transmission devices that require high durability.

(Effects of the Invention) As explained above, according to the invention set forth in claim (1), the drive pulley that transmits power between the driven pulley and the driven pulley by the timing belt is connected to the drive pulley that is rotatably supported by the rotating shaft of the drive pulley. a second pulley member that is connected to the first pulley member via a plurality of pins and one endless high-tensile flexible member and meshes with the timing belt at the outer periphery; As the driving force of the first pulley member increases, the second
By continuously decreasing and changing the amount of eccentricity of the pulley member relative to the first pulley member, the rotation of the first pulley member can be transmitted to the second pulley member at a rotation ratio of 1:1 without deceleration, and the drive Even in a drive system that increases the rotation speed of the pulley and transmits it to the driven pulley, the diameter of the drive pulley can be kept small, thereby making it possible to reduce the installation space and weight of the drive pulley and, by extension, the belt transmission device.

Furthermore, since the driving force transmitted from the first pulley member to the second pulley member is almost equally distributed across the spans of the plurality of pins and flexible members, the frictional torque loss is lower than transmission by gears. In addition to reducing noise, wear, and the like, it is also possible to improve durability by suppressing damage caused by foreign matter entering the drive force between the two pulley members.

In particular, when applied to the drive system of a bicycle, it has excellent practical effects, such as not only increasing the durability of the drive system but also reducing the force required to press the pedal.

According to the invention described in claim ('2J), the endless high-tensile-strength flexible member is a flat belt formed by embedding high-tensile threads in an elastic body, an endless film made of metal or synthetic resin, or an endless twisted thread. Since the pulley member is constructed of a rope having a shape of 100 mm, it is possible to satisfactorily satisfy the function of transmitting the driving force from the first pulley member to the second pulley member and the function of relatively displacing the axes of both pulley members.

Furthermore, according to the invention set forth in claim (3), since a rotatable sliding bearing is provided on each of the first and second pulley side pins, torque loss can be further reduced and driving force transmission efficiency can be improved. In addition, it is possible to further improve durability by suppressing wear.

Further, according to the invention described in claim (4), the first or second
By providing a flange on one of the pulley members to receive the other and restrict relative movement in the axial direction of both pulley members, it is possible to control misalignment of both pulley members in the axial direction, and to maintain the proper arrangement position of both pulley members. be able to.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 is a partially cutaway front view showing the belt transmission device in an unloaded state, and FIG.
The figure is a partially broken pressure surface view showing the same load condition. FIG. 3 is an exploded perspective view of a drive pulley in another embodiment. FIG. 4 is a diagram corresponding to FIG. 2 showing a conventional example. 1... Drive shaft (rotating shaft) 2... Driven wheel (rotating shaft) 3.3'... Drive pulley 4... First pulley member 5... Second pulley member 7... Pulley Part 7a... Teeth 8... First pulley side pin 9... Second pulley side pin 10... Endless high tensile strength flexible member 11... Driven pulley 11a... Teeth 12... ... Flange 13 ... Sliding bearing B ... Timing belt 01 ... Axis center of first pulley part 02 ... Axis center of second pulley member 03 ... Axis center of driven wheel Patent applicant Band - Kagaku Co., Ltd.

Claims (4)

[Claims] (1) A pair of rotating shafts parallel to each other, a driving and driven pulley consisting of a toothed pulley supported by the rotating shafts, and a drive and driven pulley that is wound between the two pulleys to transmit power between the two rotating shafts. and a timing belt, the driving pulley comprising: a first pulley member rotatably supported by a rotating shaft; and a first pulley member disposed on the outer periphery of the first pulley member so as to be eccentric with respect to the axis of the first pulley member; a second pulley member having teeth on its outer periphery that mesh with the timing belt; a plurality of first pulley side pins protruding from a side surface of the first pulley member at equal angular intervals on a concentric circumference; and the second pulley member. protrudingly provided on a concentric circumference having a diameter larger than the diameter of the arrangement circle of the plurality of first pulley side pins at the same angular intervals as the arrangement angle of the first pulley side pins on the side surface of the plurality of first pulley side pins; The same number of second pulley side pins, and an endless high tensile strength flexible member stretched alternately and over the entire circumference of each of the first and second pulley side pins, A belt transmission device having an automatic tension adjustment mechanism, wherein the flexible member has a length such that the flexible member is loosened when both the pulley members are in a concentric position. (2) A claim characterized in that the endless high-tensile strength flexible member is a flat belt made of a high-tensile thread embedded in an elastic body, an endless film made of metal or synthetic resin, or an endlessly twisted rope. A belt transmission device having the automatic tension adjustment mechanism according to item (1). (3) Claim (1) characterized in that each of the first and second pulley side pins is provided with a rotatable sliding bearing.
Or a belt transmission device having an automatic tension adjustment mechanism according to (2). (4) Claims (1), (2) or (
3) A belt transmission device having the automatic tension adjustment mechanism described above.