JP4924263B2 - Timing belt drive mechanism - Google Patents

Description

  The present invention adjusts a predetermined belt transmission load with a parallel leaf spring so that the distance between the rotation shafts between the pulleys of the timing belt is shortened according to the belt tension in the rotation direction of the pulleys. The present invention relates to a timing belt driving technique that generates tooth skipping.

  In a torque transmission mechanism composed of a timing belt and pulley applied to a robot arm mechanism or the like, the tooth jumps between the timing belt and the pulley when it exceeds the allowable load on the predetermined belt, or reaches it. There is a demand for a small mechanism that protects the drive mechanism itself by realizing a mechanism that causes the positional fluctuation of the belt up to the above.

  In order to realize the above-described mechanism, conventionally, as a technique for adjusting the load applied to the timing belt, a method of adjusting the tension by urging the timing belt with an idler having a predetermined elasticity by a spring or the like can be considered ( For example, see Patent Documents 1 and 2).

  A general tension adjustment mechanism using an idler will be described with reference to FIG. FIG. 5- (1) shows a case in which an elastically supported idler 30 that urges the timing belt 20 suspended between the pulley a10 and the pulley b10 ′ is arranged on one side of the belt, and FIG. These show the case where the idler 30 is symmetrically arranged on both sides of the belt.

  However, when the idler 30 is provided on one side, the belt tension increases at the portion A of the timing belt 20 when the counterclockwise rotational torque as shown in FIG. As a result, the belt tension is loosened by an amount corresponding to the position shift of the idler 30 at the part or the B portion of the timing belt 20. On the other hand, with the clockwise rotational torque, the belt tension in the B portion increases, the belt tension in the A portion is less loose, and the idler 30 is hardly displaced. Thus, when there is one idler 30, there is a problem that depending on the rotation direction of the timing belt 20, there is a difference in the characteristics up to the tooth skipping of the belt and a difference in the protection capability of the transmission mechanism.

  In order to improve this, a method of arranging the two idlers 30 so as to oppose each other at the symmetrical position is effective. However, the mechanism becomes complicated, and at the same time, there are problems such as difficulty in adjustment for ensuring symmetry. Further, since a mechanism other than the pulley is required in the timing belt path, it is difficult to shorten the distance between the pulleys, and the actuator itself such as a drive motor needs to be fixed. Therefore, it is unsuitable for downsizing, for example, the space efficiency becomes poor.

  Further, as a simple method for making the tension of the timing belt uniform, as shown in FIG. 6, the motor 50 and the support member (base 90) are integrally moved relative to the frame by the coil spring 70, and are engaged with the drive pulley 50. A method of applying tension to a driving belt (timing belt 60) to be combined has been proposed. An external force is applied to the entire frame by the coil spring 70 to absorb the belt tension (for example, Patent Document 3). In other words, this is a method in which a single-axis force is applied to the pulley to make the tension characteristics of the left-right rotating belt uniform.

However, if this is attempted to be realized by the coil spring 70, the pulley's tilting moment is not constrained, so that the rotation shaft of the pulley shakes together with the motor or the like as in the example of FIG. Moreover, when the motor is fixed, there is a problem that the tension adjustment effect of the spring is lost.
JP 10-94986 A Japanese Patent Laid-Open No. 08-152050 JP 2001-334715 A

  In order to solve the above-described problem, in the present invention, a parallel leaf spring is used instead of the coil spring applied in FIG. 6, and a function of allowing the spring to extend and contract between the rotation shafts of the pulley and an actuator for rotating the pulley Provided is a timing belt drive mechanism having a lightweight and small belt tension adjustment function and a mechanism protection function by enabling the (motor) to be stably supported in a floating state in the air.

A first invention is a timing belt drive mechanism for transmitting torque between two pulleys comprising a drive pulley and a passive pulley that receives torque transmission , each having a rotation shaft parallel to each other, and the shaft belt between the two pulleys. distance comprising a deformable parallel plate spring is the direction that varies under tension of the timing belt, to match the position of the timing belt in the direction along the rotation axis of the pulley both an end portion of the parallel leaf spring The present invention relates to a timing belt drive mechanism that is fixed to a support member of the passive pulley and that the other end of the parallel leaf spring is joined to a base member that supports the rotation shaft of the drive pulley.

  That is, according to the first invention, one end of a parallel leaf spring that can be deformed in a direction in which the distance between the axes of the pulley fluctuates is joined to a motor or the like that serves as a rotating base of the pulley, By adopting a configuration in which the end is installed at a position where the belt tension is applied, the moment that tilts the rotating shaft of the pulley is balanced with the posture maintenance moment generated at the spring fixing point, and the posture of the motor is always in the direction of the shaft. Can be maintained.

  That is, a light and small belt tension adjustment function can be realized by using a leaf spring structure in which the pulley shaft can be expanded and contracted by a spring and the actuator that rotates the pulley is floating and stably supported in the air.

  According to a second aspect of the invention, two sets of the parallel leaf springs are arranged at positions symmetrical to each other with respect to a plane passing between the axes of the two pulleys. The present invention relates to a belt driving mechanism.

  That is, according to the second aspect of the invention, the parallel leaf springs are provided at symmetrical positions with the pulley interposed therebetween, and the torsional rigidity due to the torque around the pulley can be increased, thereby realizing more stable posture control of the entire timing belt drive mechanism. The

The third invention, the first and further comprising a fastening portion to enable distance adjustment of the one end portion and the driving pulley of the parallel plate springs in the position of the timing belt or The present invention relates to a timing belt drive mechanism described in the second invention.

  That is, according to the third invention, the tension of the timing belt can be easily adjusted by adopting a configuration in which the distance between the spring fixing portion of the parallel plate spring and the pulley can be adjusted with a bolt or the like.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the parallel leaf spring includes a strain gauge on the surface thereof that detects the tension of the timing belt as a surface strain. The present invention relates to a timing belt drive mechanism.

  That is, according to the fourth invention, the deformation and distortion of the leaf spring is due to the tension load of the belt, and there is no rubbing part such as friction. High belt tension can be measured.

Fifth invention, the timing belt according to the fourth invention, characterized in that to control the driving force of the motor of the drive pulley in accordance with the tension of the timing belt which is detected as a surface strain by the strain gauge The drive mechanism.

  That is, according to the fifth aspect of the invention, the drive having the function of turning off the servo of the motor when the tension of the timing belt increases according to the measurement result by the strain gauge, for example, exceeds a predetermined value of the tension. A system can be constructed.

  The following effects are produced by the present invention described above.

  A position where the motor is connected to the drive pulley, a parallel leaf spring that can be deformed in the direction in which the distance between the pulley axes changes is joined to the motor that is the pulley's rotating base, and the belt tension is applied to the other end of the parallel leaf spring. With this configuration, the moment that tilts the rotating shaft of the pulley is balanced with the posture maintenance moment generated at the spring fixing point, and the motor posture can always be maintained in the direction of the shaft.

  In addition, by adjusting the distance between the spring fixing point of the parallel leaf spring of this mechanism and the pulley with a bolt, etc., the tension of the timing belt can be easily adjusted, and when excessive torque is applied to the pulley. The distance between the pulley shafts is shortened due to the deformation of the spring, and as a result, the belt skipping phenomenon protects the mechanism joined to the pulley, and the person who contacts the transmission destination by cutting the transmission torque It is possible to provide a power generation environment within a safe range.

  Furthermore, it is possible to measure the belt tension with high accuracy by measuring the surface strain of the leaf spring with a strain gauge, and when the belt tension rises according to the measurement result, the servo of the motor is turned off, etc. A drive system having functions can be constructed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a basic configuration of a timing belt drive mechanism according to an embodiment of the present invention. As a belt tension adjustment method that does not depend on the rotation direction of the left and right, the simplest method is to apply a force to the pulley on the line connecting the centers of the pair of pulleys. When trying to achieve with a coil spring, the pulley's tilting moment is not constrained, and as shown in the example of FIG. 6, the pulley's rotating shaft sways together with the motor, etc. Adjustment effect disappears.

  Therefore, in the present invention, a lightweight and small-sized belt is achieved by adopting a leaf spring structure in which the function of allowing the pulley shaft to extend and retract with a spring and the actuator (motor) for rotating the pulley to be floating and stably supported in the air. Realizes tension adjustment function and mechanism protection function.

  As shown in the figure, a parallel leaf spring 4 is connected to the driving pulley 2 and becomes a rotating base of the pulley 2, for example, a parallel leaf spring 4 that can be deformed in the direction in which the distance between the axes of the pulley 2 changes. Further, one end of the parallel plate spring 4 is joined at the spring fixing point A6, and the other end of the parallel leaf spring 4 is installed at the position of the spring fixing point B5 where the tension of the timing belt 3 is applied. By thus constraining the parallel leaf spring 4 in a geometrical manner, the deformation characteristics of the parallel leaf springs 4 at the spring fixing point A and the spring fixing point B become translational motions without changing their postures.

  In the figure, X represents the tension of the timing belt, Y represents a spring force applied as an external force for adjusting the tension of the timing belt, and Z represents a posture maintenance moment generated at the spring fixing point A.

  With the above-described spring arrangement, a moment that tilts the rotating shaft of the pulley 2 is balanced with the posture maintenance moment Z generated at the spring fixing point A, and the posture of the motor 1 can always be maintained in the direction of the shaft.

  Further, by attaching one end portion (spring fixing portion B) of the parallel plate spring 4 of this driving mechanism to the support member 8 with a bolt 7, the distance between the spring fixing portion B and the pulley 2 can be adjusted, and the timing belt 3 is adjusted. Can be easily adjusted.

  Furthermore, when more torque than necessary is applied to the two pulleys, the distance between the shafts of the two pulleys is shortened by the deformation of the parallel leaf spring 4, resulting in a belt jumping phenomenon. It is possible to protect the mechanism joined to the pulley and to provide a safe environment for a person who contacts the transmission destination by cutting the transmission torque.

  FIG. 2 shows an example of attaching a parallel leaf spring in the timing belt drive mechanism according to the embodiment of the present invention. In this embodiment, in order to increase the torsional rigidity with respect to the torque around the pulley, a configuration example is shown in which two sets of parallel leaf springs 4 are arranged symmetrically with respect to the pulley 2.

  FIG. 3 shows a configuration example of belt tension detection by a strain gauge according to an embodiment of the present invention. In the embodiment, (a) is an example of attachment to a single parallel leaf spring, and shows an example in which strain gauges 9a and 9b are attached to the opposing surfaces of the parallel leaf spring 4, and (b) The case where the strain gauges 9a and 9b, and 9a 'and 9b' are affixed on two sets of parallel leaf | plate springs arrange | positioned in the symmetrical position on both sides of a pulley is shown. With this strain gauge, a highly accurate strain is measured by constructing a Wheatstone bridge circuit.

  The deformation or distortion of the parallel leaf spring 4 is due to the tension load of the timing belt 3 and there is no part rubbed by friction or the like. Therefore, by measuring the surface strain of the parallel leaf spring 3 with a strain gauge, a highly accurate timing is obtained. It is possible to measure the tension of the belt. Depending on the measurement result, when the tension of the timing belt 3 increases and exceeds a predetermined value set in advance, a drive system having a function of turning off the servo of the motor 1 can be constructed.

  The correspondence between the measured value by the strain gauge attached to the parallel leaf spring 4 and the tension of the timing belt 3 is experimentally obtained, and the set value as the load limit of the belt tension that causes tooth skipping is the experimental value. And are preset.

  FIG. 4 shows a processing flow of timing belt drive control by detecting the surface strain of the parallel leaf spring according to the embodiment of the present invention. First, in step S11, the motor that drives the pulley 2 is controlled. In step S12, it is determined from the output signal of the strain gauge whether the belt tension is in an overload state that causes tooth skipping.

  As a result, if the belt tension is equal to or less than a predetermined value (a preset value set in correspondence with the strain value), the process returns to step S11 to control the rotation of the motor. If it exceeds the predetermined value, in step S13, the motor rotation is temporarily stopped, and in step S14, a recovery process for changing the set value of the belt tension is performed. In step S15, it is determined whether or not it is possible to continue with the changed recovery process. If it is possible, the process proceeds to step S11 to perform a motor rotation control process. If the continuation is impossible, the recovery process is stopped in step S16. As described above, from the detection result by the strain gauge, the motor is controlled according to the belt tension, and when the overload is applied to the timing belt, the drive mechanism can be protected by turning off the servo of the motor.

It is a figure which shows the basic composition of the timing belt drive mechanism which becomes embodiment of this invention. It is a figure which shows the example of attachment of the parallel leaf | plate spring in the timing belt drive mechanism which becomes embodiment of this invention. It is a figure which shows the structural example of the belt tension detection by the strain gauge which becomes embodiment of this invention. It is a figure which shows the processing flow of the timing belt drive control by the surface distortion detection of the parallel leaf | plate spring which becomes embodiment of this invention. It is a figure which shows the drive mechanism example 1 of the conventional timing belt. It is a figure which shows the drive mechanism example 2 of the conventional timing belt.

Explanation of symbols

1 motor 2, 2 'pulley a (for driving), pulley b
3 Timing belt 4 Parallel leaf spring 5 Spring fixing part B
6 Spring fixing part A
7 Bolt 8 Support member 9a, 9b, 9a ', 9b' Strain gauge

Claims (5)

A timing belt drive mechanism for transmitting torque between two pulleys comprising a drive pulley and a passive pulley receiving torque transmission, each having a rotation axis parallel to each other;
A parallel leaf spring that is deformable in a direction in which the distance between the axes of the two pulleys varies under the tension of the timing belt;
Said to coincide with the position of the timing belt in the direction of an end portion along the axis of rotation of both the pulleys of parallel leaf springs, fixed to a support member of the pulley, the drive pulley and the other end of the parallel leaf springs A timing belt drive mechanism characterized in that it is joined to a base member that supports a rotating shaft.   2. The timing belt drive mechanism according to claim 1, wherein two sets of the parallel leaf springs are arranged at positions symmetrical to each other with respect to a plane passing between the axes of the two pulleys. Timing belt according to claim 1 or 2, further comprising a fastening portion to enable distance adjustment of the drive pulley and the one end of the parallel leaf springs at the position of the timing belt Drive mechanism.   The timing belt driving mechanism according to claim 1, wherein the parallel plate spring includes a strain gauge on the surface for detecting the tension of the timing belt as a surface strain. Timing belt drive mechanism according to claim 4, characterized in that to control the driving force of the motor of the drive pulley in accordance with the tension of the timing belt which is detected as a surface strain by the strain gauge.

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