JPH0674307A - Auto-tension mechanism of belt transmission gear - Google Patents

Abstract

PURPOSE:To miniaturize and lighten a belt transmission gear and adjust tension by stable operation. CONSTITUTION:An internal shaft 1 is provided with an internal orbit face 1a having a single blade rotary hyperboloid and fixes a mounting member 10 and rotatably supports an outer ring 2 through the connecting members 4 and 5 fixed to an arm 200. The outer ring 2 forms an orbit 8 between the internal shaft 1 and itself and is pushed by a preload spring 6 in a direction to narrow orbit width, and torque is also transmitted from the outer ring to the internal shaft 1 through the supporting bearing 4. A plurality of rollers 3 having a cylindrical shape are arranged inclined at fixed angle from a cross section including a center shaft 1b. A thrust bearing 7 is adjusted by an adjusting screw 12 through a belleville spring 11 and stops the motion of the outer ring 2 at the position of a clutch torque to be given. The arm pushes the pulley mounted on a spring 500 by the spring 500. This constitution stably absorbs the fluctuation of tension and excessive tension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tension mechanism for a belt transmission device that adjusts the tension of a belt that is rotated by being hung on a plurality of pulleys.

[0002]

2. Description of the Related Art A belt transmission device is sometimes provided with a mechanism for applying tension to a belt and automatically adjusting the tension so that the tension is released when an excessive tension is applied. For example, from the crankshaft of an automobile engine,
As a mechanism for transmitting rotation to a camshaft, a cooler, a dynamo, etc., a timing belt is used instead of the conventional silent chain, and an automatic tension mechanism is provided to adjust the tension of this belt. That is, in such a belt, a sudden torque change at the time of starting the engine or a momentary reverse rotation causes a belt tooth breakage, or a flapping of the belt due to a rotation fluctuation of the engine causes a tooth breakage, or As the temperature rises gradually after the engine starts to reach steady operation, the members may expand due to thermal expansion and the pulley spacing may expand, and excessive tension may be applied to the belt to cut it, so it is necessary to prevent such accidents. Because there is.

As an auto-tension mechanism of such a belt transmission device, conventionally, an arm is pulled by a tension spring, a tension pulley attached to the tip of the arm is pressed against the belt, and a hydraulic mechanism is provided on the other end side of the arm. Devices were provided to maintain the tension applied to the belt and to relieve tension when it was too high. However, since such a conventional device uses a hydraulic mechanism, it has a large shape and weight,
There are problems such as being expensive, having a complicated mechanism, changing the viscosity of oil with temperature, and having unstable performance due to the mechanism itself.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems in the prior art and to provide an auto-tension mechanism for a belt transmission device which is small in size, low in cost and stable in performance.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention according to claim 1 is an auto-tension mechanism for a belt transmission device for adjusting the tension of a belt which is hung on a plurality of pulleys and rotated. In, a tension pulley that contacts the belt, an arm that rotatably supports the tension pulley at one end side, and a first biasing unit that biases the tension pulley in a direction of contacting the belt,
A torque relief device coupled to the other end of the arm,
And the torque relief device has an inner rotating body having an inner raceway surface forming a single-leaf rotation hyperboloid about the central axis, and the inner raceway around the central axis so as to form a raceway between the inner raceway surface and the inner raceway surface. An outer ring having an outer ring raceway surface that forms a single-leaf rotation hyperboloid, and is connected to the outer ring via torque transmitting means so that the outer ring is movable in the central axis direction and torque is transmitted between the outer ring and the outer ring. And a connecting member that is connected to the inner rotating body so as to be rotatable at a constant position in the central axis direction, and has a cylindrical rolling surface, and the center line of the track is inclined at a constant angle from a section including the central axis. And a plurality of rollers arranged in the circumferential direction of the raceway, the surfaces of which are in linear contact with the inner raceway surface and the outer raceway surface, and the outer race in the central axis direction, with a space between the raceways. No. 1 that biases in the direction of narrowing Urging means and movement stopping means for stopping the movement of the outer ring in the direction of narrowing the track spacing at a predetermined position, and one of the inner rotating body or the connecting member is provided with the arm. Is coupled to the other end side of the above so as to transmit torque, and the rotation of the other one of the above is fixed, so that when the arm rotates in the direction of coming into contact with the belt, the space between the tracks widens. In addition to the above, the invention according to claim 2 is characterized in that the roller is inclined to the third, and the third urging means for urging the movement stopping means in a direction in which the distance between the tracks widens, Adjusting means for adjusting the position of the three urging means in the central axis direction, and the invention according to claim 3 is characterized in that, in addition to the characteristics of the invention according to claim 1 or 2, Is the other end of the arm And butterflies.

[0006]

According to the invention of claim 1, the following action is brought about by the configuration as described above. For example, if the inner rotating body is fixed and its rotation is restrained, and the other end side of the arm is connected to the connecting member, the tension pulley attached to one end side of the arm may change depending on the tension of the belt in the belt transmission device. When the arm moves, the arm swings and the outer ring rotates via the connecting member. When the inner rotating body and the other end side of the arm are connected, by fixing the connecting member and restraining the rotation thereof, when the tension pulley moves, the outer ring does not rotate but the inner ring rotates. .

Next, each of the surfaces of the inner rotating body and the outer ring facing each other is made into a single-leaf rotating hyperboloid, and a plurality of rollers are inclined in a raceway formed on both sides to make line contact with both raceway surfaces. Then, the outer ring is urged by the second urging means in the direction of narrowing the track interval, so that an action as a rolling bearing clutch occurs between the inner rotating body and the outer ring. That is, when the tension pulley moves and the outer ring rotates via the other end side of the arm and the connecting member, the rollers are guided by both raceways (inner and outer raceways) of the outer ring and the inner rotating body, and rotate on each of them. While revolving, the inclination causes the inner rotating body and the outer ring to move in opposite directions in the central axis direction. As a result, due to the relationship between the inclination direction of the rollers and the rotation direction of the rotating body, a separating force or a pulling force is generated between the inner rotating body and the outer ring in the central axis direction. When the outer ring, which is movable with respect to the connecting member, moves in the axial direction and a separation force is generated between the two, the track spacing increases, and free rotation between the inner rotating body and the outer ring becomes possible. When the pulling force is generated, the track spacing is narrowed, and the inner rotating body and the outer ring are clutched via rollers. In this case, since the tension pulley moves in the direction in which the tension pulley contacts the belt by the urging force of the first urging means and the one end side of the arm moves in that direction, the rollers are inclined so that the orbital interval is widened. When the tension pulley loosens and pushes the belt, the inner and outer wheels rotate freely, and when the tension of the belt increases and the tension pulley moves in the direction to push it back from the belt, the inner and outer wheels move in the clutch direction. Rotate.

As a result, if the belt has slack, the belt is freely pushed by the urging force of the first urging means and an appropriate tension is applied to the belt.

On the other hand, when the tension of the belt increases and the tension pulley is pushed back by the belt, the outer ring is rotated toward the clutch side, the track gap is narrowed, and the outer ring receives a clutch torque corresponding to the amount of advance in the axial direction. Given,
This torque is transmitted to the tension pulley via the connecting member and the arm, and a force that balances the pushing-back force by the belt is generated to give an appropriate tension to the belt.

Here, this clutch torque becomes large in accordance with the twist angle generated between the inner rotating body and the outer ring due to relative rotation, and thus the amount of movement of the outer ring. However, according to the present invention, since the movement stopping means for stopping the movement of the outer ring at the predetermined position is provided, the outer ring is not twisted and moved further, so that the clutch torque generated at the position of the outer ring is , The maximum clutch torque. Therefore, if the belt is too tight and excessive tension is applied to the belt, and the belt pushes the tension pulley in response to this tension and the torque that rotates the outer ring exceeds the maximum clutch torque, the outer ring rotates with that torque and the tension The pulley moves in the direction of being pushed by the belt, and the tension on the belt is not further applied, so that accidents such as cutting of the belt are prevented.

As described above, according to the first aspect of the present invention, the normal tension fluctuation of the belt is absorbed by the torque absorbing capacity of the torque relief device, and when the tension becomes excessive, it is moved by the moving means. No more tension is applied, preventing accidents. In this case, the clutch torque is stable because there is no variation because it is obtained by the action of rolling friction due to microdeformation between the roller and the inner rotating body and outer ring, and the sliding friction in the axial direction of the roller. . Furthermore, since the torque relief device has a rolling bearing shape, it does not require a large sliding part or a part that retains fluid, unlike the conventional braking device that uses sliding friction and fluid resistance. It becomes small.

According to the invention of claim 2, in addition to the constitution of the invention of claim 1, third urging means for urging the movement stopping means in the direction of widening the track interval, and the third urging means. Since the adjusting means for adjusting the position of the bearing in the central axis direction is provided, the position of the bearing can be finely adjusted via the third urging means. That is, by adjusting the position of the third urging means by the adjusting means, it is possible to adjust the bearing position via the urging force, so that it is determined by the axial position of the bearing by utilizing the characteristics of the urging means. Fine adjustment of clutch torque is possible.

According to the invention of claim 3, since the connecting member and the outer ring are made of the same member, the number of parts of the product is reduced.

[0014]

EXAMPLES FIGS. 1A and 1B show a schematic structure of a belt transmission device to which an auto-tension mechanism of the belt transmission device of the embodiment is applied. The present auto-tension mechanism includes a tension pulley 200 that comes into contact with a belt 104 that is wound around a plurality of pulleys 101, 102, 103, and an arm 3 that rotatably supports the tension pulley 200 at one end side.
00 and a torque relief device 400 coupled to the other end of the arm 300. Also, tension pulley 2
As a first urging means for urging 00 in the direction of contacting the belt 104, in the example of FIG. 1A, a coil spring 500 built in the torque relief device 400 is provided as shown in FIG. In the example of 1 (b), the arm 300 is attached with the coil spring 500 ′ whose one end side is fixed. Reference numeral 105 is a fixed tension pulley. With such a configuration, the tension pulley 200 moves in a direction perpendicular to the belt surface due to the tension or slack of the belt 104, and the arm 300 swings around the center of the torque relief device 400.

FIG. 2 shows an example of the configuration of the torque relief device 400. The torque relief device 400 includes an inner shaft 1 as an inner rotating body, an outer ring 2, rollers 3, a connecting member 4,
A preload spring 6 as torque transmitting means and second urging means,
The thrust bearing 7 as the movement stopping means, the disc spring 11 as the third urging means for urging the thrust bearing 7 in the direction to widen the space between the raceways, and the position of the disc spring 11 in the direction of the central axis 1b. And an adjusting screw 12 as an adjusting means that enables adjustment.

The inner shaft 1 is provided with an inner raceway surface 1a which forms a single-leaf rotating hyperboloid around the central axis 1b, and is fixed to the support member 10 at both ends 1c, and the support member 10 is fixed to the frame of the belt transmission device or the like. By doing so, the rotation is restricted. Reference numerals 10a, 10b, and 10c are mounting holes for the support member 10. The inner shaft 1 supports the connecting member 4 and the arm supporting member 5 rotatably at a fixed position in the direction of the central shaft 1b.

The outer ring 2 has a raceway 8 between itself and the inner raceway surface 1a.
Is provided with an outer ring raceway surface 2a that forms a single-leaf rotational hyperboloid around the central axis 1b, and is connected by a preload spring 6 that is also torque transmitting means so that the outer ring raceway surface 2a is movable in the central axis 1b direction and torque is transmitted. It is connected to the member 4. In addition,
In the present embodiment, as will be described later, the preload spring 6 also serves as a torque transmission means, but the torque transmission means may be a ball spline, a torque transmission pin, or the like, and may be a component different from the preload spring. .

As shown in FIG. 3, the roller 3 has a cylindrical rolling surface, and in the raceway 8, the center line of the roller 3 is inclined with a constant angle β (for example, 15 °) from the cross section including the central axis 1b. A plurality of them are arranged in the circumferential direction, and their surfaces are in linear contact with the inner raceway surface 1a and the outer ring raceway surface 2a. Further, the rollers 3 are held in position by a cage 9 so that they can rotate smoothly without interfering with each other. The inclination direction of the roller 3 is a direction in which the distance between the raceways 8 is widened when the arm 300 rotates in the direction in which the arm 300 contacts the belt 104, that is, a direction in which the inner and outer races 1 and 2 are freely rotated. .

Raceways 1a and 2a of the inner shaft 1 and the outer ring 2
Is a single-leaf rotating hyperboloid obtained by rotating the hyperbola shown in the following equation around the center line 1b so as to linearly contact the roller 3. yi ² / ai ² −xi ² / bi ² = 1 yo ² / ao ² −xo ² / bo ² = 1 where x _i and x _o are the centers of the inner ring raceway surface 1 a and the outer ring raceway surface 2 a, respectively. Distance in the direction of line 1b, y _i ,
_yo is the distance from the center line 1b of the inner ring raceway surface 1a and the outer ring raceway surface 2a in an arbitrary section including the center line 1b, and ai, bi, ao, and bo are constants. F = 9, r =, where F is the distance from the center line 1b to the center of the raceway 4 on the reference surface (the origin surface of the hyperbola) on the small diameter side of the inner and outer rings, r is the radius of the roller 3, and β is the inclination angle. 1.5, β = 15
When the calculation in the case of ° is performed (the calculation is omitted because it is complicated), the values of ai, bi, ao, and bo are about 7.
5, 30.1, 10.5, 37 are given, and the shape of the single-leaf rotating hyperboloid of the inner and outer ring raceways is given.

The preload spring 6 as the urging means and torque transmitting means has a structure as shown in FIG. The preload spring 6 is made of an elastic body and transmits the urging force and the torque, and the protrusions 6a on the outer ring 2 side and the connecting member 4 side, respectively.
6b, the tip surfaces of the convex portions 6a and 6b and one side surface are in pressure contact with the front surface and one side surface of the concave portions 2b and 4a of the outer ring 2 and the connecting member 4, respectively, and the biasing force and torque are transmitted between them. It has become so. The biasing force acts in the direction of narrowing the track interval. The figure shows that the preload spring 6 applies thrust forces from the outer ring 2 and the connecting member 4 to the thrusts T ₁ and T ₂
And torques M ₁ and M ₂ (T ₁ and T ₂ and M ₁ and M ₂ are opposite in direction and equal in size, respectively) and deformed.

The thrust bearing 7 stops at a predetermined position the movement of the outer ring 2 in the direction of narrowing the track spacing in the direction of the central axis 1b. At a predetermined position of the bearing 7, the tension of the belt 104 becomes large, and the tension pulley 200 causes the belt 1 to move.
04, the arm 300 rotates, the outer ring 2 rotates via the connecting member 4, and the roller 3 moves the outer ring 2 into the central shaft 1b.
Is moved in a direction that narrows the space between the tracks 8 in the direction,
When the clutch torque gradually increases, the belt 10
It is a position where the outer ring 2 is stopped before the tension of 4 becomes excessive. In this case, in this embodiment, the thrust bearing 7 is attached to the inner shaft 1 so as to be movable in the direction of the central axis 1b, and the position of the disc spring 11 can be adjusted by the adjusting screw 12 to set the predetermined position. It is like this. As a result, the tension of the belt 104 increases, the disc spring 11 is compressed, the thrust bearing 7 moves on the inner shaft 1 and balancely stops at a predetermined position. Therefore, the maximum tension of the belt is The tension corresponds to the clutch torque.

With this structure, the operation of the present auto-tension mechanism is as follows. For example, when the belt 104 becomes loose, the urging force of the coil spring 500 causes the arm 30 to move.
0 pushes the tension pulley 200 and rotates in the right direction when viewed from the right side in FIG. 2, and rotates the outer ring 2 in the same direction via the connecting member 4. As a result, the rollers 3 are rotated in the same direction, a separation force is generated between the inner and outer wheels 1 and 2, and the outer ring 2 is freely rotated without clutching between them. Therefore, when the belt 104 is loosened, the tension pulley 200 follows it and the looseness of the belt is removed.

Next, when the belt 104 is stretched and the tension pulley 200 is pushed, the operation opposite to the above is performed and the inner and outer races 1 and 2 are clutched. Then, in opposition to the pushing back force of the tension pulley 200, a pushing force corresponding to the clutch torque is generated from the outer ring 2 via the arm 300, and these forces become a force corresponding to the tension of the belt 104, and the belt is balanced. An appropriate tension will be applied to 104. That is, the normal fluctuation of the belt tension is absorbed by the torque absorbing function between the inner and outer races 1 and 2 via the rollers 3. On the other hand, when the tension becomes higher than a certain level, the movement of the outer ring 2 is stopped at a predetermined position by the bearing 7, the torque above a certain level is not applied to the arm 300, and the tension pulley 200 is pushed back, as described above.
Excessive tension is prevented. Since such tension adjustment of the torque relief device is performed mainly by rolling of the roller, its operation is extremely reliable and stable.

The clutch torque as described above is given by the equation M = Aδ ^3/2 (M = A'α ^3/2 ) where δ is the amount of advance of the outer wheel after clutching (this corresponds to the twist angle α). Given in. Here, A and A ′ are torsion spring constants, which are values determined for each device and can be easily obtained by calculation or experiment. Since the clutch torque can be calculated in this way, if the allowable maximum tension of the belt 104 is given, the maximum clutch torque is calculated from this, the movement amount δ of the outer ring 2 is calculated from the above equation, and the predetermined value of the bearing 7 is calculated. The position can be determined.

The magnitude of such a clutch torque can be adjusted by adjusting the position of the thrust bearing 7 with a screw or the like. However, as shown in the example of the torque curve in FIG. 5, the clutch torque changes greatly with a slight axial displacement of the outer ring 2, and therefore, in order to accurately obtain the desired set torque (for example, the torque M _{1 in the} figure), The position of the thrust bearing 7 needs to be adjusted extremely finely. For this reason, even if the position of the thrust bearing 7 is adjusted with a screw or the like, the rotation thereof directly causes an angular displacement and hence an axial displacement, so that it may be difficult to accurately set the torque. In the apparatus of the present embodiment, the angle due to the screw, that is, the axial displacement is once applied to the disc spring 11, so that the position of the thrust bearing 7 can be finely adjusted by its characteristic.

FIG. 6 shows another embodiment of the torque relief device 400. Since the main structural portion is the same as that of the embodiment of FIG. 2, the description of such a portion will be omitted.
In the present embodiment, the outer ring 2 side is fixed and its rotation is restrained, and the inner shaft 1 is connected to the arm 300 to rotate. In addition, the coil spring 500 ′ is shown in FIG.
As shown in (b), it is directly connected to the arm 300.
Reference numeral 1c ′ is an arm fixing portion that is attached so as to transmit torque to the arm 300 and rotate it. Reference numeral 4'denotes a housing as a connecting member, which is fixed to a frame or the like of the belt transmission device shown by a chain double-dashed line in the drawing. Further, in this embodiment, the position of the bearing 7 is fixed. In the figure, the direction of arrow A is the clutch side, and the opposite direction is the free rotation side.

[0027]

As described above, according to the present invention, in the invention of claim 1, the device can be made compact and lightweight.
In addition, by a stable and reliable operation, it is possible to absorb the belt tension fluctuation and release the excessive tension. Claim 2
In the invention described above, in addition to the above, adjustment of the maximum tension of the belt can be facilitated. According to the invention of claim 3, the number of parts of the product can be reduced and the cost can be reduced.

[Brief description of drawings]

1A and 1B are explanatory views of a belt transmission device to which an auto-tension mechanism of the belt transmission device according to the embodiment is applied.

FIG. 2 is a sectional view of an auto-tension mechanism of the belt transmission device according to the embodiment.

FIG. 3 is a perspective view showing the arrangement of the rollers.

FIG. 4 is a perspective view of the preload spring.

FIG. 5 is a curve diagram showing the relationship between the twist angle or the outer ring displacement and the clutch torque.

FIG. 6 is a sectional view of an auto-tension mechanism of a belt transmission device according to another embodiment.

[Explanation of symbols]

 1 inner shaft (inner rotating body) 1a inner shaft raceway surface (inner raceway surface) 1b central shaft 1c blade mounting portion (joint portion) 2 outer ring 2a outer ring raceway surface 3 roller 4 connecting member 4'housing (connecting member) 6 preload spring (Torque transmitting means, second biasing means) 7 Thrust bearing (movement stopping means) 8 Orbit 11 Disc spring (third biasing means) 12 Adjusting screws (adjusting means) 101, 102, 103 Pulleys (plural pulleys) 104 Belt 200 Tension pulley 300 Arm 400 Torque relief device 500, 500 'Coil spring (first urging means)

Claims (3)

[Claims] 1. An auto-tension mechanism for a belt transmission device that adjusts tension of a belt that is hung on a plurality of pulleys and is rotated, and a tension pulley that contacts the belt and the tension pulley is rotatably supported at one end side. An arm, a first urging means for urging the tension pulley in the direction of contacting the belt, and a torque relief device coupled to the other end side of the arm, the torque relief device comprising: An inner rotating body having an inner raceway surface that forms a single-leaf rotation hyperboloid about the central axis, and an outer ring raceway surface that forms a single-leaf rotation hyperboloid about the central axis so as to form a trajectory between the inner raceway surface and the inner raceway surface. And an outer ring that has the outer ring, is movable in the central axis direction, and is coupled to the outer ring via torque transmission means so that torque is transmitted between the outer ring and the outer ring. A coupling member connected with the rotatable manner the inner rotating member at a predetermined position of the mandrel direction,
The rolling surface has a cylindrical shape, and a plurality of surfaces are provided in the inner raceway surface and the outer ring raceway surface with the center line of the raceway being inclined at a certain angle from the cross section including the central axis and arranged in the circumferential direction of the raceway. A linear contact roller, a second urging means for urging the outer ring in the direction of the central axis in the direction of narrowing the space between the raceways, and a movement of the outer ring in the direction of narrowing the space between the raceways. A movement stopping means for stopping at a predetermined position, and one of the inner rotating body and the connecting member is coupled to the other end side of the arm so as to transmit torque, and The rotation of the other of the rollers is fixed, and the rollers are inclined so that the distance between the tracks is widened when the arm rotates in a direction in which the arm contacts the belt. Tension machine . 2. A third urging means for urging the movement stopping means in a direction in which the space between the tracks widens, and an adjusting means for adjusting the position of the third urging means in the central axis direction. The auto-tension mechanism for the belt transmission device according to claim 1, further comprising: 3. The automatic tension mechanism for a belt transmission device according to claim 1, wherein the connecting member is on the other end side of the arm.