JP4922854B2 - Belt drive - Google Patents

Description

  The present invention relates to a belt transmission device provided with a torque limiter.

  2. Description of the Related Art Conventionally, for example, a power transmission mechanism in an agricultural machine or the like is provided with a torque limiter that cuts off a predetermined or higher torque transmission. As an example of such a torque limiter, for example, a break type that breaks a pin or the like with a predetermined torque is known. Although the breaking torque limiter is inexpensive, the torque (limit torque) at which the torque limiter operates is unstable (that is, the accuracy of the limit torque is low), and the pin must be replaced after the torque limiter is activated. There is a problem that it cannot be easily restored and takes a long time for restoration (that is, poor repeatability and returnability).

  On the other hand, for example, in Patent Document 1, when the displacement of the transmission belt occurs, the pulley body is displaced by utilizing the change in the position of the axial load applied to the pulley shaft, thereby causing the transmission belt to meander. A belt-type power transmission mechanism that realizes a torque limiter by providing a self-aligning pulley that prevents the above is disclosed. That is, this self-aligning pulley has a pulley body around which a transmission belt is wound, and a supporting means for supporting the pulley body so as to be rotatable about its pulley axis and swingable about a predetermined pivot axis. The pivot is tilted at a predetermined tilt angle on the front side in the rotational direction of the pulley body with respect to the axial load direction when viewed along the pulley axis direction. With this configuration, the self-aligning pulley imparts a predetermined aligning force to the transmission belt when the transmission belt is offset.

The transmission belt in this belt transmission device is adapted to receive a thrust force that urges it in one direction of the pulley width by adjusting the winding direction of the core wire, etc. The vehicle travels in a state where the alignment force from the alignment pulley and the thrust force are balanced. On the other hand, when the drive pulley slips and the transmission belt stops running, the aligning force from the self-aligning pulley disappears, so that the transmission belt moves in one direction of the pulley width by the thrust force, and the drive pulley It will fall off the pulley surface. That is, the torque limiter is activated.
JP 2006-300154 A

  The torque limiter disclosed in Patent Document 1 has high repeatability / returnability and relatively high accuracy of limit torque. However, in this belt transmission device, when the traveling speed of the transmission belt is relatively high, the kinetic energy of the transmission belt becomes relatively high. Therefore, when the drive pulley slips, the transmission belt instantaneously drops from the pulley. When the running speed of the belt is relatively low, the kinetic energy of the transmission belt is relatively low. Therefore, even when the drive pulley slips, there is a problem that the transmission belt is difficult to drop off from the pulley.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a belt transmission device that includes a self-aligning pulley and realizes a torque limiter. Is to ensure that it operates.

According to one aspect of the present invention, a belt transmission includes a drive flat pulley, a driven flat pulley, a self-aligning pulley, and the drive flat pulley, the driven flat pulley, and the self-aligning pulley wound around the drive pulley. and a transmission flat belt for transmitting power of the flat pulley to the driven flat pulley, the self-aligning pulley, rotating the pulley body, wherein the transmission flat belt is wound, the pulley body, around the pulley shaft Supporting means that freely and swingably supports a predetermined pivot axis, and the pivot axis is located on the front side in the rotational direction of the pulley body with respect to the direction of the axial load when viewed along the pulley axis direction. A spiral groove is formed on the pulley surface of the drive flat pulley so as to advance in one direction in the width direction of the pulley.

According to this configuration, since the belt transmission device includes the self-aligning pulley, the transmission flat belt is prevented from meandering by the aligning force applied from the self-aligning pulley to the transmission flat belt.

In other words, if the transmission flat belt is offset on the pulley body of the self-aligning pulley and the axial load is shifted from the pivot position in the width direction of the pulley body, the axial load generates a rotational moment around the pivot axis. Thus, the pulley body is rotationally displaced. Since the pivot axis is tilted forward in the rotational direction of the pulley body with respect to the axial load direction (that is, the tilt angle is more than 0 degree and less than 90 degrees), the pulley body is offset by the transmission flat belt. As the side moves in the direction of the axial load, that is, if the height in the axial load direction is viewed, the transmission flat belt is inclined so that the side on which the transmission flat belt is offset is low and the opposite side is high, and before and after being orthogonal to the axial load direction When viewed in the direction (the direction in which the flat belt is in contact with the pulley body), the offset side of the flat belt moves to the front in the belt traveling direction, and is oblique to the flat belt. It comes into contact.

When the pulley main body is inclined in the axial load direction, a return force in a direction opposite to the offset direction acts on the transmission flat belt. At the same time, by the pulley body is rotated at Hasukai state to the transmission flat belt, so that the return force in the opposite direction acts in the direction offset from said pulley body for transmission flat belt. By this way the centering force applied to the transmission flat belt from the self-aligning pulley, meandering of the transmission flat belt is prevented.

The self-aligning pulley, whereas during belt running can impart aligning power for that transmission flat belt, can not impart the aligning force to the transmission flat belt when the belt run is stopped. For this reason, as the load of the driven flat pulley exceeds a predetermined level, the driving flat pulley slips and the traveling of the transmission flat belt stops, and the aligning force from the self-aligning pulley disappears.

Here, wherein the pulley surface of the drive flat pulley, since the helical grooves going in one direction of the pulley width direction is formed, when the driving flat pulley is slipping, the spiral groove, the transmission flat belt, A biasing force in the direction in which the spiral advances is applied. By this urging force, the transmission flat belt to which no aligning force is applied is dropped from the driving flat pulley. Thus, power transmission flat belt, since the driving spur pulley spiral groove is formed may drop by slipping, even driving flat pulley when the running speed of the transmission flat belt is relatively low slips, transmission Rights The belt will surely fall off the drive flat pulley. Thus, the torque limiter in the belt transmission device is reliably operated.

Here, it is preferable that the diameter of the driving flat pulley is set smaller than the diameter of the driven flat pulley. By doing so, the contact area of the drive flat pulley (contact angle), when compared with the contact area at the driven flat pulley, with who the contact area of the drive flat pulley is reduced, by forming the spiral groove Accordingly, the contact area of the driving flat pulley is further reduced, so that when the load of the driven flat pulley exceeds a predetermined value, the driving flat pulley side surely slips. Consequently, as explained above, by the spiral groove of the drive flat pulley, transmission flat belt is securely from falling from the driving flat pulley.

As described above, according to the present invention, in a belt drive system that realizes a torque limiter by providing a self-aligning pulley, by forming a helical groove in the pulley surface of the driving flat pulley, when the driving flat pulley is slipping The transmission flat belt can be reliably detached from the driving flat pulley, and the torque limiter of the belt transmission can be reliably operated.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  1 and 2, 1 is a drive pulley (flat pulley), 2 is a driven pulley (flat pulley), 4 is a self-aligning pulley, and the drive pulley 1 and the driven pulley 2 are connected to a transmission belt. A flat belt 3 is wound around. The self-aligning pulley 4 is pressed against the back surface of the flat belt 3 on the slack side of the belt by an urging arm 41 so as to apply tension to the flat belt 3 as a tension pulley. Although the flat belt 3 is not shown, the flat belt 3 may be a cord flat belt, for example.

  The drive pulley 1 is fitted into a drive shaft (not shown) and is integrally rotated with the drive shaft. The pulley diameter of the driving pulley is set to be smaller than the pulley diameter of the driven pulley, whereby the contact angle θ1 of the driving pulley 1 is set to be relatively small.

  A spiral groove 11 is formed on the pulley surface of the drive pulley 1 as shown in FIGS. 3 and 6B, and this spiral groove 11 is one direction in the pulley width direction (in FIG. It is formed so as to proceed in the downward direction. Therefore, as indicated by an arrow in FIG. 3, the spiral groove 11 is inclined with respect to the left-right direction orthogonal to the pulley axis in the plan view of the drive pulley 1.

  The driven pulley 2 is fitted into a driven shaft (not shown) arranged in parallel to the drive shaft, and is integrally rotated with the driven shaft. As described above, the pulley diameter of the driven pulley 2 is set to be larger than the pulley diameter of the drive pulley 1, and the contact angle θ2 is set to be relatively large. Further, no groove is formed on the pulley surface of the driven pulley 2, and the pulley surface is flattened (see FIG. 6A).

  As shown in FIGS. 4 and 5, the self-aligning pulley 4 includes a cylindrical pulley body 5 around which a flat belt 3 is wound, and a pulley body 5 that is rotatable about a pulley axis C1 and about a pivot axis C2. And support means 10 for supporting the movement freely.

  The support means 10 includes a cylindrical shaft member 11 that supports the pulley body 5 via bearings 12 and 12, a support rod 13, and a pin 17 that forms a pivot C2.

  The support rod 13 has a base end portion fixed to the biasing arm 41 and a distal end side serving as a support portion 13 b that is inserted into the cylindrical hole of the shaft member 11. The support portion 13b is formed by cutting a portion corresponding to the diametrical direction of the cross-sectional circular rod into a D shape, and flat sliding surfaces 13c and 13c that are parallel to each other are formed by the D cut. Has been.

  As shown in FIG. 1, the urging arm 41 has one end rotatably attached to an apparatus main body (not shown) and the other end to which the support rod 13 is fixed. A tension coil spring 42 is attached. The biasing arm 41 presses the self-aligning pulley 4 against the flat belt 3 so that tension is applied to the flat belt 3 by the biasing force of the tension coil spring 42.

  The inner peripheral surface constituting the cylindrical hole of the shaft member 11 is opposed to flat sliding surfaces 11a and 11a which are slidably in contact with the sliding surfaces 13c and 13c of the support rod 13, and this sliding Two arcuate surfaces connecting both side edges of the surfaces 11a and 11a are formed to face each other.

  The pins 17 of the support means 10 are disposed so as to penetrate the support portion 13b of the support rod 13 in a direction perpendicular to the sliding surfaces 13c and 13c, and both ends thereof are slidable on the shaft member 11. It is fixed to the shaft member 11 by being inserted into a support hole formed orthogonal to the moving surfaces 11a, 11a. Then, as shown in FIG. 5, the pin 17 is positioned at the center position of the pulley body 5 with respect to the pulley width direction, and with respect to the axial load direction L with respect to the rotation direction of the pulley body 5. The pulley body 5 is tilted at a predetermined tilt angle α on the front side in the rotational direction (see FIG. 1).

  Between the arc surface on both sides of the support portion 13 b of the support rod 13 and the arc surface on both sides of the cylindrical hole of the shaft member 11, the shaft member 11 swings with the pulley body 5 around the pin 17. Allowable gaps 15 and 15 are formed. Accordingly, the pulley body 5 is supported by the support means 10 so as to be rotatable about the pulley axis (rotation center axis) C1 and swingable about the pivot axis C2 orthogonal to the pulley axis C1.

  Next, the operation of this belt transmission device will be described. 1 and 2, that is, in the normal state where the flat belt 3 is wound around the driving pulley 1 and the driven pulley 2 and power transmission is performed by the flat belt 3, near the center in the pulley width direction. When the flat belt 3 on the pulley body 5 approaches one side of the pulley body 5, the shaft load is shifted from the position of the pin 17 to one side of the pulley body 5 and acts on the shaft member 11. As a result, a rotational moment about the pin 17 acts on the shaft member 11, and the shaft member 11 rotates and displaces around the pin 17 together with the pulley body 5. Specifically, the pulley body 5 is in an oblique state with respect to the flat belt 3 such that the side on which the flat belt 3 is offset becomes the front side in the belt traveling direction, and the side on which the flat belt 3 is offset is low. , And incline in the direction of the axial load L so that the opposite side becomes higher.

  As described above, when the pulley body 5 is rotationally displaced, the flat belt 3 receives a return force in a direction in which the pulley body 5 returns to the offset direction due to the inclination of the pulley body 5 in the axial load direction, and the pulley body 5 is obliquely crossed. Thus, it is twisted in the direction to return the offset, and receives a return force in the direction to return the offset.

  Therefore, both the force (alignment force) of the returning force due to the pulley body 5 being inclined and the returning force due to the inclination of the pulley body 5 act on the traveling flat belt 3, Accordingly, the flat belt 3 travels stably at a position where the alignment force and the offset force are balanced.

  On the other hand, when the load of the driven pulley 2 increases to a predetermined value or more (such as when an impact torque is applied to the driven pulley 2), the drive pulley 1 slips. That is, in this belt transmission device, as described above, the diameter of the drive pulley 1 is smaller than the diameter of the driven pulley 2, and the contact area of the drive pulley 1 is smaller (θ1 <θ2). 6 (a) and 6 (b), since the spiral groove 11 is formed on the pulley surface of the drive pulley 1, the contact area is further reduced by the amount of the groove. For this reason, when the load of the driven pulley 2 increases and exceeds a predetermined value, the drive pulley 1 slips. In the belt transmission device provided with the flat belt 3, the relationship between the tension of the flat belt 3 and the maximum torque of the drive pulley 1 is constant. In this belt transmission device, a predetermined and constant tension is applied to the flat belt 3 by the self-aligning pulley 4 (tension pulley), so that the belt transmission device, in other words, the belt transmission device. The limit torque of the torque limiter at is set with high accuracy.

  Since the traveling of the flat belt 3 is stopped by the slip of the drive pulley 1, the aligning force applied to the flat belt 3 from the self-aligning pulley 4 is lost. On the other hand, since the driving pulley 1 has a spiral groove 11, the spiral groove 11 imparts a biasing force in the spiral advance direction to the flat belt 3. Due to this urging force, the flat belt 3 moves in one direction in the pulley width direction, specifically, as shown by a white arrow in FIG. . Thus, the torque limiter is activated.

  When returning after the torque limiter is activated, it is only necessary to return the flat belt 3 onto the drive pulley 1.

  Therefore, in this belt transmission device, by using the self-aligning pulley 4, the flat belt 3 can stably travel during normal times, and high transmission efficiency by the flat belt 3 can be obtained.

  On the other hand, when the driving pulley 1 slips due to the load on the driven pulley 2 and the belt 3 stops traveling, the self-aligning pulley 4 does not function and is formed on the pulley surface of the driving pulley 1. Due to the spiral groove 11, a biasing force in the pulley width direction is applied to the flat belt 3. Together, even if the running speed of the flat belt 3 is relatively low and its kinetic energy is relatively small, the flat belt 3 can be reliably detached from the drive pulley 1. In addition, when the advance direction of the spiral groove 11 on the pulley surface is reversed, the dropping direction of the flat belt 3 is reversed. For this reason, this configuration has an advantage that the falling direction of the flat belt can be arbitrarily set.

  Further, as described above, in this belt transmission device, the return after the operation of the torque limiter is extremely easy, and the repeatability and returnability are high. Accordingly, since the torque limiter having high repeatability and resetting performance is configured with a simple structure using the self-aligning pulley 4 while achieving high accuracy of the limit torque, the cost can be greatly reduced. it can.

  A gentle crown may be attached to the outer peripheral surface of the pulley body 5. If the crown is gentle, it is possible to avoid applying a large load to the flat belt 3.

  The self-aligning pulley 4 has the pivot C2 formed by the pin 17. However, the present invention is not limited to this, and any configuration can be used as long as the pulley body 5 can be rotated around the pivot C2. May be adopted.

  In addition, in the self-aligning pulley 4, the pivot axis C2 is orthogonal to the pulley axis C1 of the pulley body 5. However, the present invention is not limited to this. In other words, it may be tilted by a predetermined angle α with respect to the axial load direction L.

  In the above-described embodiment, the self-aligning pulley 4 is used as a tension pulley. However, a tension pulley is separately provided, and the self-aligning pulley 4 is used to adjust a belt length, a contact angle, a belt traveling direction, and the like. You may make it use for the other use of a belt transmission.

  As described above, in the belt transmission device according to the present invention, the torque limiter is configured by the self-aligning pulley, and the operation of the torque limiter covers a wide range from the low speed to the high speed of the belt. For example, it is useful in that it can be used for automobiles, agricultural machines, various industrial machines, home appliances, and other devices.

It is a front view of a belt transmission device. It is a top view of the apparatus. It is a top view of a drive pulley. It is a front view of a self-aligning pulley. It is a longitudinal cross-sectional view (VV sectional drawing of FIG. 4) of a self-aligning pulley. (A) It is sectional drawing which shows the belt winding state in a driven pulley, (b) The belt winding state in a drive pulley.

1 Drive pulley 2 Driven pulley 3 Flat belt (power transmission belt)
4 Self-aligning pulley 5 Pulley body 10 Support means 11 Spiral groove C1 Pulley shaft C2 Axis α Inclination angle

Claims (2)

A driving flat pulley,
A driven flat pulley,
A self-aligning pulley;
A transmission flat belt wound around the driving flat pulley, driven flat pulley and self-aligning pulley and transmitting the power of the driving flat pulley to the driven flat pulley;
The self-aligning pulley is
A pulley body around which the transmission flat belt is wound;
Supporting means for supporting the pulley body so as to be rotatable around a pulley axis and swingable around a predetermined pivot axis;
The pivot is tilted at a predetermined tilt angle on the front side in the rotational direction of the pulley body with respect to the direction of the axial load as viewed along the pulley axis direction;
A belt transmission device in which a helical groove is formed on a pulley surface of the driving flat pulley so as to advance in one direction in the pulley width direction. The belt transmission device according to claim 1,
A belt transmission device in which a diameter of the driving flat pulley is set smaller than a diameter of the driven flat pulley.

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