JP5403704B2 - Low backlash gear mechanism and device - Google Patents

Description

  The present invention relates to a low backlash gear mechanism and apparatus for automatically reducing backlash between a gear and a gear tooth surface when the gear is stopped.

In order for the pair of gears to operate smoothly, backlash between the tooth surfaces is necessary. However, in a device that requires high accuracy, a device with less backlash is required. For example, this tendency is remarkable in a reduction gear used for a conveying device that requires repeated positioning accuracy. When the output shaft stops when the backlash is large, the reaction force of the inertial force of the conveyed object As a result, when the torque opposite to the direction in which the output shaft has been rotated is generated, the stop position slightly fluctuates, and thus there is a problem that the work cannot be stopped accurately and reliably at the fixed position. For this reason, there is a demand for automatically eliminating backlash when stopping. Further, when the forward rotation and reverse drive of the motor are repeated, a low backlash gear mechanism and device that can cope with the forward rotation and reverse rotation of the motor are required.
Many low backlash gear mechanisms and devices have been developed so far, examples of which include the following.

JP 2001-74126 A JP 2007-198600 A JP-A-8-74972

Patent Document 1 discloses a low backlash gear which includes two gears on the same axis and a torsion coil spring which is biased in the rotational direction with respect to the other gear by one adjusting member and a set screw. A mechanism is disclosed. According to this configuration, the strength of the reaction force of the torsion coil spring can be easily adjusted by rotating the adjusting member and fixing it with the set screw in a state where a torsional moment is applied to the torsion coil spring.
In Patent Document 2, two gears are provided on the same axis, a long hole is provided in one gear, and a pressing mechanism including a steel ball, an elastic body, and an adjusting means is provided in the hole, The guide portion provided in the gear is inserted into the pressing mechanism, and the groove provided in the guide portion is in contact with the steel ball of the pressing mechanism. When the gear rotates, the guide portion is rotated from the guide portion to the elastic body via the steel ball. Disclosed is a low backlash gear mechanism that reduces the backlash by applying a moment to compress the elastic body and applying a reaction force of the elastic body to the guide portion when the gear stops and rotating the gear provided with the guide portion. Yes. In addition, it is supposed that the pressure applied to an elastic body can be adjusted beforehand by the adjustment means provided in a press mechanism.
Patent Document 3 includes a drive gear, two neutral gears that mesh with drive gears provided on separate shafts, a driven gear that is provided coaxially with each neutral gear, and an output gear that meshes with the driven gear. A desired torsional torque is applied to one of the shafts on which the neutral gear and the driven gear for connecting these gears are provided with a torque wrench, etc., and in this state, the shaft is fixed by a wedge-shaped clamping member and engaged with the output gear. A low backlash gear device for generating a phase difference is disclosed. According to this device, a phase difference occurs between the two driven gears due to the torsional torque applied to one shaft, and a pressing force acts in a direction away from each other, thereby reducing backlash. ing.

In the case of a low backlash gear mechanism such as that disclosed in Patent Document 1, it is desirable that the gear rotates in the direction in which the coil is wound because of the characteristics of the torsion coil spring. In addition, since the torsional moment of the torsion coil spring is adjusted by the adjusting member and then fixed by the set screw, it is difficult to assemble.
In the low backlash gear mechanism as in Patent Document 2, when adjusting the pressure applied to the elastic body by the adjusting means, it is inconvenient because the pressing mechanism must be detached from the gear each time it is adjusted, and then reassembled after adjustment. . Also, the smaller the size of the gear, the more difficult it will be to handle since it will handle a much smaller pressing mechanism than the gear.
A low backlash gear device such as that of Patent Document 3 is difficult to assemble because it must be fixed by a wedge-shaped clamping member in a state where a torsion torque is applied to one of the shafts with a torque wrench or the like. In addition, this configuration has a problem that it is difficult to adjust torsional torque.

  Therefore, in view of the problems of the prior art described above, the present invention provides a low backlash gear mechanism and apparatus that can cope with the case where the motor is rotated forward and backward, is easy to assemble, and can easily adjust torsional torque. Its purpose is to provide.

The present invention relates to a main gear connected to a shaft, a sub gear provided rotatably on the same axis and provided with at least one hemispherical hole, a ball fitted into the hemispherical hole, and the ball fitted therein. A groove having a V-shaped circumferential section having a size that can be coupled is provided, and is connected to the shaft and is movable in the axial direction, a nut that is screwed into the shaft, and between the nut and the driven plate Comprising an elastic body provided,
In order from one end of the shaft, the nut, elastic body, driven plate, ball, sub gear, main gear are arranged,
In the driven plate, the deepest part of the hemispherical hole into which the ball of the sub gear is fitted and the deepest part of the groove are displaced in the rotation direction, and the ball is in contact with one inclined surface of the groove. In the state, pressed by the elastic body ,
The ball moves in a direction that eliminates a positional shift between the deepest portion of the hemispherical hole and the deepest portion of the groove, and generates a torsion torque in the main gear and the sub gear to reduce backlash. The above problem was solved by the low backlash gear mechanism.

  Further, according to claim 2, a driven flange having a hemispherical hole into which at least one ball is fitted, and an elliptical long hole for inserting the screw, which are attached to the sub gear with a screw. It is suitable to provide.

  Further, as in claim 3, an output gear or an input gear having two gears provided on the output shaft or the input shaft that meshes with the input gear or the output gear and the input gear or the output gear provided on the input shaft or the output shaft. A low backlash in which one of the output gear or the input gear is a main gear and the other gear is a sub gear, and the low backlash gear mechanism of claim 1 or 2 is incorporated in the output gear or the input gear. A gear device is preferable.

  Further, as in claim 4, an input gear provided on the input shaft, an output gear provided on the output shaft, an intermediate output gear provided between the input gear and the output gear and meshing with the input gear, and the output gear A first intermediate gear and a second intermediate gear, the intermediate input gear of the first intermediate gear or the second intermediate gear is a main gear or a sub gear, and the intermediate output gear is a sub gear or a main gear. The low backlash gear device according to claim 1 or 2 is preferably incorporated into the first intermediate gear or the second intermediate gear.

  According to the present invention, in the driven plate, the deepest part of the hemispherical hole into which the ball of the sub gear is fitted and the deepest part of the groove having a V-shaped cross section in the circumferential direction are displaced in the rotation direction. Since it is configured to be pressed by the elastic body in contact with one of the slopes, the driven plate is pressed by the reaction force of the elastic body, so that the ball moves in a direction to fit into the groove, An attempt is made to eliminate the positional shift between the deepest part of the hemispherical hole and the deepest part of the groove. For this reason, torque in the relative rotational direction, that is, torsional torque is generated in the driven plate and the sub gear. Since this driven plate is connected to the shaft, the torsional torque applied to the driven plate is communicated to the main gear connected to the shaft through the shaft. As a result, the torsional torque is applied to the main gear and the sub gear, The gear and sub-gear try to rotate in relative directions. Thus, when the main gear and the sub gear are engaged with the other gear, either the main gear or the sub gear comes into contact with the tooth surfaces on both sides of the other gear, so that the backlash can be reduced.

  Further, in order from one end of the output shaft, a nut, an elastic body, a driven plate, a ball, a sub-gear, and a main gear are arranged, and the driven plate has a deepest portion of a hemispherical hole into which the sub-gear ball is fitted and a cross section V Because it is a simple structure in which the ball is in contact with one of the slopes of the groove and is attached to be pressed by an elastic body, with the deepest part of the letter-shaped groove being shifted in the rotational direction. Can be assembled.

  In addition, since the reaction force of the elastic body, that is, the force pressing the driven plate can be adjusted by the screwing angle of the nut screwed into the output shaft, the magnitude of the torsion torque can be easily adjusted.

  Further, as in claim 2, a configuration is provided that includes a driven flange that is attached to the sub-gear with a screw and has a hemispherical hole into which the ball is fitted and an elliptical oblong hole as viewed from the front for inserting the screw. If so, the mounting position of the screw can be changed within the range of the long hole and the mounting angle of the driven flange to the sub gear can be adjusted. As a result, the circumferential position of the hemispherical hole can be adjusted. It is possible to easily adjust the deviation between the deepest part of the hemispherical hole and the deepest part of the V-shaped groove.

  According to a third aspect of the present invention, in the low backlash gear device comprising the output gear having the input gear provided on the input shaft and the two gears provided on the output shaft meshing with the input gear, one of the output gears is provided. The low backlash gear mechanism according to claim 1 or 2 is preferably incorporated in the output gear with the gear as the main gear and the other gear as the sub gear. In this case, the torque when the input gear rotates is clockwise. In either case of rotation or counterclockwise rotation, it acts in the opposite direction to the torsional torque applied to the main gear or sub gear. Specifically, when torque is applied from the input gear to the main gear, the torque from the input gear is immediately transmitted to the output shaft because the main gear is connected to the output shaft. At this time, the input gear and the output gear rotate in the state at the time of assembly, that is, in a state where there is little backlash, and when the rotation stops, the state where backlash remains low. On the other hand, when torque is applied from the input gear to the sub gear, the sub gear is rotatably provided on the output shaft, so that torque from the input gear is not immediately transmitted to the output shaft. Therefore, when the torque from the input shaft exceeds the torsional torque applied to the subgear, a force in the direction opposite to the torsional torque acts on the subgear, and the direction in which the ball tends to escape from the groove. In other words, a force is applied in a direction in which the deepest portion of the hemispherical hole and the deepest portion of the V-shaped groove are further shifted. Accordingly, an axial force is applied to the driven plate as the ball moves so as to escape through the V-shaped groove. Since the driven plate is movable in the axial direction, the driven plate moves in the axial direction, and the elastic body in contact with the driven plate is compressed by the amount of movement. When the input gear stops, the driven plate is pushed back in the axial direction by the reaction force of the elastic body, so that the ball tends to fit into the V-shaped groove, that is, the deepest part and the cross section of the hemispherical hole. Since it moves in a direction that eliminates the positional deviation from the deepest part of the V-shaped groove and generates a torsion torque in the main gear and sub gear, it automatically returns to the state at the time of assembly, that is, the state with less backlash. It will be. Here, when the main gear connected to the output shaft rotates in a direction that reduces backlash, the output shaft rotates. For this reason, the output shaft may rotate slightly in the process of reducing backlash after the motor is stopped. When the sub gear, not the main gear, rotates in a direction that reduces backlash, the sub gear is rotatably provided on the output shaft, so the output shaft does not rotate. Note that when the input shaft is directly connected to the motor, when the motor is stopped, the input shaft is fixed so as not to rotate due to the servo lock. Therefore, when the motor is stopped, the main gear or sub gear is backlashed by torsion torque. The input shaft does not rotate through the input gear even if it rotates in the direction to reduce the rotation.

  In another aspect of the present invention, the low backlash gear device includes an input gear having an output gear provided on the output shaft and two gears provided on the input shaft meshing with the output gear. One of the gears may be a main gear, the other gear may be a sub-gear, and the low backlash gear mechanism of claim 1 or 2 may be incorporated in the input gear. The basic operating principle in this case is the same as that when a low backlash gear mechanism is incorporated in the output gear on the output shaft. When the input shaft is directly connected to the motor, the input shaft is fixed so that it does not rotate by the servo lock of the motor when the motor is stopped. The main gear to be connected may not be able to rotate in a direction that reduces backlash. At this time, the sub gear is rotated by the torsional torque, and the output gear is rotated until the tooth surface of the output gear contacts the main gear to reduce backlash. Therefore, the output shaft may rotate slightly.

  Further, as in claim 4, an input gear provided on the input shaft, an output gear provided on the output shaft, an intermediate output gear provided between the input gear and the output gear and meshing with the input gear, and the output gear A first intermediate gear and a second intermediate gear, the intermediate input gear of the first intermediate gear or the second intermediate gear is a main gear or a sub gear, and the intermediate output gear is a sub gear or a main gear. According to the configuration in which the low backlash gear mechanism of claim 1 or 2 is incorporated in the first intermediate gear or the second intermediate gear, the low backlash gear mechanism of the present invention is also applied to the two-stage gear. be able to.

  Further, as in the case of claim 3, the output shaft may rotate slightly after the motor stops depending on whether the main gear or the sub gear rotates when reducing backlash.

The front view of the low backlash gear mechanism of 1st Embodiment of this invention. FIG. 2 is a circumferential cross-sectional view of the main part of FIG. 1. The front view at the time of a stop (assembly | attachment) at the time of incorporating 2nd Embodiment of this invention in the gear of 1 step | paragraph. The principal part expanded horizontal sectional view at the time of the stop (assembly) of FIG. FIG. 4 is an enlarged cross-sectional view of a main part at the time of rotation in FIG. 3. The front view at the time of a stop (assembly | attachment) at the time of incorporating 3rd Embodiment of this invention in a two-stage gear. The front view at the time of the fixed direction rotation of FIG. (A) The front view of the reduction gear device using this invention, (b) The principal part side surface sectional drawing of (a). FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 8.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. However, the present invention is not limited to this embodiment. In each figure, backlash is exaggerated for convenience.

  The low backlash gear mechanism 10 of FIG. 1 is provided with a main gear 15 connected to a shaft 12 and a sub gear 25 rotatably provided on the shaft 12, provided with one hemispherical hole 17, and a hemispherical hole. 17 is provided with a ball 24 to be fitted to 17, a groove 18 a having a V-shaped circumferential section that is large enough to fit the ball 24, connected to the shaft 12, and driven to the axially movable plate 18 and shaft 12. A nut 14 to be screwed and a disc spring 16 which is an elastic body provided between the nut 14 and the driven plate 18 are provided. The hemispherical hole 17 may have a shape other than the hemispherical shape, such as a concave groove shape, as long as it can hold the ball 24. Further, the groove 18 a may have a V-shaped circumferential cross section, and a roller may be used instead of the ball 24.

  As shown in FIG. 2, the shaft 12 and the driven plate 18 are connected by being key-fastened by a key portion 18b. For this reason, the main gear 15 connected to the shaft 12 and the driven plate 18 rotate in the same direction. Further, since the positions of the deepest portion of the hemispherical hole 17 and the deepest portion of the groove 18a are shifted in the circumferential direction, the ball 24 is assembled in a state of being in contact with one inclined surface of the groove 18a. At this time, when the driven plate 18 is pressed in the axial direction by the disc spring 16, the ball 24 moves in a direction to fit into the groove 18 a, so that the driven plate 18 is in the left rotation direction and the sub gear 25 is in the right rotation direction. Try to rotate. As a result, the torque in the counterclockwise direction of the driven plate 18 is transmitted to the main gear 15 via the shaft 12, so that a relative torque, that is, a torsion torque, can be applied to the main gear 15 and the sub gear 25. As shown in FIG. 1, the main gear 15 and the sub gear 25 are engaged with the other gear 55 in accordance with the positional relationship between the deepest portion of the hemispherical hole 17 where the torsional torque is generated and the deepest portion of the groove 18a. Any one of the main gear 15 and the sub gear 25 is pressed against the tooth surfaces 56 and 57 of the gear 55, so that backlash can be reduced. Further, when the main gear 15 or the sub gear 25 is in contact with the tooth surface 56 or 57 of the other gear 55, the positions of the main gear 15, that is, the driven plate 18, and the sub gear 25 are fixed, and the ball 24 is further in the groove 18a. Since it cannot move in the direction to be fitted, it is stable in the state shown in FIG. In FIG. 2, when the position of the deepest part of the hemispherical hole 17 and the deepest part of the groove 18a is small and the ball 24 is in contact with both slopes of the groove 18a, the disc spring 16 drives the driven plate. Since no torsional torque is generated even when 18 is pressed, the state shown in FIG. 2 is required when assembled (stopped). In FIG. 2, the deepest part of the hemispherical hole 17 is located on the left side and the deepest part of the groove 18a is located on the right side. However, if this is reversed, it is possible to apply a torsional torque in the opposite direction. Not too long. Moreover, since the force with which the disc spring 16 presses the driven plate 18 can be adjusted by changing the tightening angle of the nut 14 depending on how the nut 14 is screwed into the shaft 12, the magnitude of the torsion torque can be easily reduced. Can be adjusted. Therefore, it is possible to easily realize a torsion torque according to the use application and environment of the low backlash gear mechanism 10. It is obvious from the laws of mechanics that the moment decreases as the distance between the position where the hemispherical hole 17 and the groove 18a are provided and the shaft 12 is shorter, and the moment increases as the distance is longer.

Next, FIG. 3 is a front view when the one-stage low backlash gear device 100 using the low backlash gear mechanism 10a is stopped (assembled). In the low backlash gear device 100, an input gear 55a provided on an input shaft 52a connected to a motor (not shown) and a main gear 15a and a sub gear 25a of a low backlash gear mechanism 10a provided on an output shaft 12a are engaged with each other. doing. In addition, although the structure which reversed the input shaft 52a and the output shaft 12a, ie, the low backlash gear mechanism 10a can also be provided on the input shaft 52a, since the structure is fundamentally the same, the description is abbreviate | omitted. .
The sub gear 25a includes a hemispherical hole 28a into which the ball 24 is fitted, and a driven flange 28 having an elliptical long hole 28b as viewed from the front for inserting the screw 26. In this way, by interposing the driven flange 28, the mounting position of the screw 26 on the sub gear 25a is changed within the range of the long hole 28b, and the mounting angle of the driven flange 28 on the sub gear 25a is adjusted, so that the hemisphere The position of the mold hole 28a can be shifted. On the other hand, as shown in FIG. 4, the driven plate 18 is key-fastened to the output shaft 12 a by the key portion 18 b after the driven flange 28 is attached to the sub gear 25 a by the screw 26. For this reason, the position of the groove 18a provided in the driven plate 18 is fixed. Accordingly, by adjusting the mounting position of the driven flange 28 and adjusting the position of the hemispherical hole 28a, the degree of displacement between the deepest part of the hemispherical hole 28a and the deepest part of the V-shaped groove 18a in section. Can be easily adjusted. The low backlash gear mechanism 10a presses the driven plate 18 by pressing the plurality of coil springs 16a with the nuts 14a. Thus, springs such as a disc spring and a coil spring can be applied as the elastic body, and an elastic body such as rubber can also be applied depending on the case.

  4 and 5 are enlarged cross-sectional views of main parts of the low backlash gear mechanism 10a when the low backlash gear device 100 is stopped (assembled) and rotated. For convenience of explanation, hatching is not performed. When the low backlash gear device 100 is stopped (assembled), as shown in FIG. 4, the nut 14a is screwed into the output shaft 12a and presses the coil spring 16a, so that the driven plate 18 is pressed by the coil spring 16a. Will be. Accordingly, the ball 24 fitted in the hemispherical hole 28a tends to move in a direction to fit in the groove 18a, so that the main gear 15a is passed through the output shaft 12a key-fastened from the driven plate 18 by the key portion 18b. Torque is generated in the left rotation direction indicated by the arrow A, and in the right rotation direction indicated by the arrow B in the sub gear 25a. As shown in FIG. 3, when the main gear 15a contacts the tooth surface 56a of the input gear 55a and the sub gear 25a contacts the tooth surface 57a of the input gear 55a, the ball 24 of FIG. 4 tends to fit into the groove 18a. 4, when the low backlash gear device 100 is stopped (assembled), the positions of the deepest part of the hemispherical hole 28a and the deepest part of the groove 18a are shown in FIG. Is shifted in the circumferential direction. That is, since the main gear 15a is pressed against the tooth surface 56a of the input gear 55a and the sub gear 25a is pressed against the tooth surface 57a of the input gear 55a by the torsional torque, backlash is reduced. When the position of the deepest portion of the hemispherical hole 28a and the deepest portion of the groove 18a is small and the ball 24 is in contact with both slopes of the groove 18a, the driven plate 18 is pressed by the coil spring 16a. However, since no torsional torque is generated, the low backlash function cannot be obtained unless the state shown in FIG.

  Even if the input gear 55a of the low backlash gear device 100 shown in FIG. 3 rotates in the left or right direction, a torque in the direction opposite to the torsional torque applied to the main gear 15a or the sub gear 25a acts. . Specifically, when the input gear 55a rotates counterclockwise and gives torque to the main gear 15a, the main gear 15a is connected to the output shaft 12a, so the torque from the input gear 55a is immediately transmitted to the output shaft 12a. Will be. At this time, as shown in FIG. 4, the input gear 55a and the output gear 10a are rotated in the assembled state, that is, in a state where there is little backlash, and when the rotation stops, backlash is also generated. It remains few. On the other hand, when the input gear 55a rotates to the right and gives torque to the sub gear 25a, the sub gear 25a is rotatably provided on the output shaft 12a, so that the torque from the input gear 55a is immediately transmitted to the output shaft 12a. When the torque from the input shaft 52a exceeds the torsional torque applied to the sub-gear 25a, the sub-gear 25a starts to rotate in the direction opposite to the torsional torque. The main part of the low backlash gear mechanism 10a during rotation of the low backlash gear device 100 at this time is the direction in which the ball 24 exits the groove 18a opposite to the direction in which the torsion torque is generated, as shown in FIG. The driven plate 18 is moved in the axial direction by the moving distance, and the coil spring 16a is compressed. At this time, the ball 24 is in the position of the position of the main gear 15a and the sub gear 25a until the force that the ball 24 tries to escape from the groove 18a and the reaction force of the coil spring 16a are balanced by the torque transmitted from the input gear 55a. The tooth surface 57a of the input gear 55a is in contact with the main gear 15a and the sub gear 25a so that the position of the deepest part of the hemispherical hole 28a and the deepest part of the groove 18a is not displaced any more until it is removed from the groove 18a. Move in the direction you want. Then, when the rotation of the input gear 55a stops, the reaction force of the compressed coil spring 16a automatically returns to the state shown in FIG. If the ball 24 is completely removed from the groove 18a at the time of rotation, a torsional torque cannot be generated even if a reaction force of the elastic body is applied. Therefore, the ball 24 is not completely removed from the groove 18a at the time of rotation. It is necessary to set the strength of the reaction force of the elastic body or the degree of displacement between the deepest part of the hemispherical hole 28a and the deepest part of the groove 18a.

  Next, the operation of the low backlash gear device 100 will be described in detail. For example, when the input shaft 52a of the low backlash gear device 100 of FIG. 3 rotates counterclockwise, torque is transmitted to the main gear 15a from the tooth surface 56a of the input gear 55a, and the output connected to the main gear 15a and the main gear 15a. The shaft 12a starts to rotate clockwise. That is, the torque from the input shaft 52a is immediately transmitted to the output shaft 12a. At this time, the driven plate 18 key-fastened to the output shaft 12a, the nut 14a screwed into the output shaft 12a, and the coil spring 16a provided between the nut 14a and the driven plate 18 are also rotated clockwise. Begin. On the other hand, the torque from the input gear 55a is not transmitted to the sub gear 25a. At this time, torque in the clockwise direction is applied to the main gear 15a from the input gear 55a, and torsional torque in the clockwise direction is applied to the sub gear 25a, so that the disc spring 16a is not compressed. The main gear 15a and the sub gear 25a rotate clockwise so as to be driven. Therefore, during rotation, the torque is not transferred to the output shaft 12a from the input shaft 52a in the state shown in FIG. 4, that is, in the state shown in FIG. It will be. Therefore, even when the rotation of the input shaft 52a stops, the output shaft 12a does not rotate after the stop because the backlash remains as shown in FIG.

  On the other hand, when the input shaft 52a of FIG. 3 rotates to the right, torque is transmitted from the tooth surface 57a of the input gear 55a to the sub gear 25a. Since the sub gear 25a is rotatably provided on the output shaft 12a, the torque is not immediately transmitted to the output shaft 12a, and the magnitude of the torsion torque applied to the sub gear 25a by the torque from the input shaft 52a. Is exceeded, the sub gear 25a starts to rotate counterclockwise in the direction opposite to the torsional torque. At this time, the torque is also transmitted to the driven flange 28 attached to the sub gear 25a and the ball 24 in the hemispherical hole 28a provided in the driven flange 28, and starts rotating in the same direction as the sub gear 25a. Therefore, the ball 24 tends to exit the groove 18a until the torque applied to the ball 24 and the reaction force of the coil spring 16a are balanced, or until the tooth surface 57a of the input gear 55a contacts the main gear 15a. 5, the positional relationship between the ball 24 and the groove 18 a shown in FIG. 5 is obtained, and torque is transmitted from the ball 24 to the driven plate 18. As a result, torque is transmitted to the output shaft 12 a. When the input shaft 52a stops from this state, the reaction force of the coil spring 16a moves the ball 24 in a direction in which it tries to fit into the groove 18a, and a torsion torque is generated. Accordingly, since the sub gear 25a rotates to the right and the main gear 15a rotates to the left, the output shaft 12a slightly rotates to the left along with the left rotation of the main gear 15a, and at the same time, the input gear 55a in contact with the sub gear 25a slightly changes. Turn left. As shown in FIG. 3, the main gear 15a stops when the tooth surface 56a of the input gear 55a and the sub gear 25a contact the tooth surface 57a of the input gear 55a. Here, when the input shaft 52a is directly connected to a motor (not shown) and the motor is fixed so as not to rotate due to the servo lock, the input shaft 52a is fixed so as not to rotate due to the servo lock of the motor. The torque does not rotate the input gear 55a and the sub gear 25a in contact therewith, and only the main gear 15a rotates counterclockwise to reduce backlash. Since the main gear 15a is connected to the output shaft 12a, the output shaft 12a connected to the main gear 15a also slightly rotates as the main gear 15a rotates.

Next, the operation when the low backlash gear mechanism 10a is provided on the input shaft, which is different from the case where the low backlash gear mechanism 10a is provided on the output shaft, will be described in the following paragraphs. The input shaft 52a in FIG. 3 will be described as the output shaft 52a, the input gear 55a as the output gear 55a, and the output shaft 12a as the input shaft 12a.
When the input shaft 12a rotates counterclockwise, torque is transmitted from the main gear 15a to the tooth surface 56a of the output gear 55a, and the output gear 55a and the output shaft 52a start to rotate clockwise. That is, the torque from the input shaft 12a is immediately transmitted to the output shaft 52a. At this time, since the torque from the input shaft 12a is in the same direction as the torsional torque applied to the main gear 15a, the state shown in FIG. In other words, torque is transmitted from the input shaft 12a to the output shaft 52a with little backlash. Therefore, even when the rotation of the input shaft 12a is stopped, the output shaft 52a does not rotate after the stop because the backlash remains as shown in FIG.

On the other hand, when the input shaft 12a rotates to the right, a slight gap exists between the main gear 15a and the tooth surface 57a of the output gear 55a. Therefore, when the main gear 15a starts to rotate clockwise, the driven plate 18 Similarly, the groove 18a also rotates to the right, and the ball 24 is rotated until the torque applied to the groove 18a and the reaction force of the coil spring 16a are balanced, or until the main gear 15a contacts the tooth surface 57a of the output gear 55a. As shown in FIG. 5, the positional relationship between the ball 24 and the groove 18a is reached, and torque is transmitted from the groove 18a to the driven flange 28 through the ball 24 and the hemispherical hole 28a. As a result, torque is transmitted from the main gear 15a or the sub gear 25a to the output gear 55a and the output shaft 52a.
Then, when the input shaft 12a stops, the ball 24 moves in a direction to fit into the groove 18a by the reaction force of the coil spring 16a, and a torsion torque is generated. Accordingly, since the main gear 15a rotates to the left and the sub gear 25a rotates to the right, the input shaft 12a slightly rotates to the left along with the left rotation of the main gear 15a, and at the same time, the output gear 55a in contact with the sub gear 25a slightly changes. Turn left. Then, as shown in FIG. 3, the main gear 15a stops when the tooth surface 56a of the output gear 55a and the sub gear 25a contact the tooth surface 57a of the output gear 55a. Here, when the input shaft 12a is directly connected to a motor (not shown) and the motor is fixed so as not to rotate by a servo lock, the main gear 15a to be connected to the input shaft 12a reduces backlash. Cannot rotate in the direction. Accordingly, the sub-gear 25a rotates clockwise with the torsional torque in contact with the tooth surface 57a of the output gear 55a, and the output gear 55a is rotated until the tooth surface 56a of the output gear 55a contacts the main gear 15a. Rotates slightly.

  Next, FIG. 6 is a front view when the two-stage low backlash gear device 200 using the low backlash gear mechanism 10b is stopped (assembled). The low backlash gear device 200 is provided between an input gear 55b provided on an input shaft 52b connected to a motor (not shown), an output gear 65 provided on an output shaft 62, and between the input gear 55b and the output gear 65. The low backlash gear mechanism 10b is provided as a first intermediate gear 30 and a second intermediate gear. The first intermediate gear 30 includes a first intermediate output gear 35 and a first intermediate input gear 45, and the low backlash gear mechanism 10b includes a sub gear 25b, which is a second intermediate output gear, on the shaft 12b. It has a main gear 15b which is a second intermediate input gear. The first intermediate output gear 35 and the sub gear 25b, and the first intermediate input gear 45 and the main gear 15b have the same number of teeth, and the sub gear 25b is more than the first intermediate output gear 35 and the first intermediate input gear 45. The tooth width of the main gear 15b is preferably narrow. Further, the ball 24 is fitted into the hemispherical hole 28a, the position of the deepest part of the hemispherical hole 28a is shifted from the deepest part of the circumferential cross-section V-shaped groove 18a, and the ball 24 is one of the grooves 18a. The driven plate 18 is pressed by the disc spring 16b which is an elastic body in a state in contact with the slope. Like the low backlash gear mechanism 10b, a hemispherical hole 28a provided in the driven flange 28, a ball 24 fitted therein, a circumferentially cross-sectional V-shaped groove 18a, and a plurality of screws 26 and long holes 28b are provided. It is good also as a structure. Similarly to the low backlash gear mechanisms 10 and 10a, the low backlash gear mechanism 10b generates a torsional torque that is a torque in a relative direction in the sub gear 25b and the main gear 15b. Therefore, when the low backlash gear device 200 is stopped (assembled), the tooth surface 56b of the input gear 55b and the first intermediate output gear 35 are connected to the tooth surface 57b of the input gear 55b and the sub gear as shown in FIG. 25b is the tooth surface 66 of the output gear 65 and the main gear 15b, the tooth surface 67 of the output gear 65 and the first intermediate input gear 45 are in contact, and the tooth surfaces 56b and 57b on both sides of the input gear 55b and the output gear. The tooth surfaces 66 and 67 on both sides of 65 are the first intermediate output gear 35 of the first intermediate gear 30, the first intermediate input gear 45, the main gear 15b of the low backlash gear mechanism 10b, or the gear of the sub gear 25b. Since it is in contact, there is little backlash.

  Here, the operation of the low backlash gear device 200 will be specifically described. When the input shaft 52b of the low backlash gear device 200 of FIG. 6 rotates counterclockwise, torque is transmitted from the tooth surface 56b of the input gear 55b to the first intermediate output gear 35, and is provided coaxially with the first intermediate output gear 35. The first intermediate input gear 45 that has started to rotate clockwise. The torque of the first intermediate input gear 45 is transmitted to the output gear 65 through the tooth surface 67 of the output gear 65, and the output gear 65 and the output shaft 62 rotate counterclockwise. That is, when the input shaft 52b rotates counterclockwise, torque is immediately transmitted to the output shaft 62. The torque transmitted to the output gear 65 is transmitted as a torque in the clockwise direction from the tooth surface 66 of the output gear 65 to the main gear 15b, but a torsional torque in the clockwise direction is applied to the sub gear 25b. Since the input gear 55b rotates counterclockwise, the disc spring 16b is not compressed, and the main gear 15b and the sub gear 25b rotate clockwise so as to be driven. In other words, since the rotation is performed with little backlash, even if the input shaft 52b stops from this state, the backlash remains small.

  On the other hand, when the input shaft 52b in FIG. 6 rotates to the right, torque is transmitted from the tooth surface 57b of the input gear to the sub gear 25b as the input gear 55b rotates to the right. With the torque transmitted to the sub gear 25b, as shown in FIG. 5, the ball 24 moves in a direction to escape from the groove 18a and compresses the disc spring 16b (coil spring 16a in FIG. 5) through the driven plate 18. As shown in FIG. 7, the tooth surface 57 b of the input gear 55 b comes into contact with the first intermediate output gear 35, and the input gear 55 b starts to transmit torque to the first intermediate output gear 35. Thus, the torque from the input gear 55b is transmitted to the output gear 65 through the first intermediate gear 30 and the low backlash gear 10b. If the torque applied from the input gear 55b to the sub gear 25b and the reaction force of the disc spring 16b are balanced before the tooth surface 57b of the input gear 55b contacts the first intermediate output gear 35, the main gear 15b outputs the output gear. Torque is transmitted to 65. That is, in any case, torque is transmitted from the input shaft 52b to the output shaft 62 in a state where the disc spring 16b of the low backlash gear mechanism 10b is compressed. Therefore, when the input shaft 52b stops, a torsion torque is applied to the low backlash gear mechanism 10b by the reaction force of the compressed disc spring 16b. At this time, torque in the clockwise direction is given to the sub gear 25b, and the input gear 55b is rotated counterclockwise through the tooth surface 57b of the input gear 55b. When the input shaft 52b is directly connected to the motor, the input shaft 52b is fixed so as not to rotate by the servo lock of the motor, so that the sub gear 25b and the input gear 55b in contact therewith do not rotate. On the other hand, the output gear 65 rotates to the right by the torque in the left rotation direction applied to the main gear 15b, and the torque is transmitted from the tooth surface 67 of the output gear 65 to the first intermediate input gear 45, and the first intermediate input gear 45 is rotated to the left. Rotate. Then, the coaxial first intermediate output gear 35 also rotates counterclockwise and contacts the tooth surface 56b of the input gear 55b. At this time, the low backlash gear device 200 is completely stopped. Thus, the low backlash gear device 200 automatically returns to the state shown in FIG.

  FIG. 8A shows a speed reducer 300 incorporating the low backlash gear mechanism 10b. As shown in FIG. 5B, the first intermediate gear 30 and the low backlash gear mechanism 10b, which is the second intermediate gear, are arranged side by side so that the sub gear 25b and the intermediate output gear 35 partially overlap in the axial direction. By arranging, the height and the axial dimension of the reduction gear 300 can be made compact.

  As shown in FIG. 9, the motor M is connected to the orthogonal gear 50, and a parallel gear 55 c is provided on the input shaft 52 c of the orthogonal gear 50. The parallel gear 55c meshes with the sub gear 25b of the low backlash gear mechanism 10b, the main gear 15b is provided on the shaft 12b of the low backlash gear mechanism 10b, and the main gear 15b meshes with the output gear 65. Thus, by incorporating the low backlash gear mechanism 10b into the reduction gear 300, a reduction gear with less backlash can be realized. If the output gear 65 is a rack, a rack and pinion with less backlash can be realized. That is, the low backlash gear mechanism of the present invention can be applied as long as the gear meshes with the parallel gear.

  As described above, according to the low backlash gear mechanism of the present invention, backlash can be reduced in both cases of forward and reverse rotation of the motor. In addition, since the structure is simple, it can be easily assembled, and the magnitude of the torsion torque applied to the main gear and the sub gear can be easily adjusted simply by adjusting the mounting angle depending on the screwing condition of the nut.

10 Low backlash gear mechanism 10a Low backlash gear mechanism (output gear)
10b Low backlash gear mechanism (second intermediate gear)
12, 12b shaft 12a output shaft (input shaft in paragraphs 0028 and 0029)
14, 14a, 14b Nut 15, 15a, 15b Main gear (intermediate input gear)
16, 16a, 16b Elastic body 17 Hemispherical hole (provided in sub gear)
18 Driven plate 18a Circumferential cross section V-shaped groove 24 Ball 25, 25a, 25b Sub gear (intermediate output gear)
26 Screw 28 Driven flange 28a Hemispherical hole (provided on the driven flange)
28b Elliptical long hole when viewed from the front 30 First intermediate gear 35 Intermediate output gear 45 Intermediate input gear 52a, 52b Input shaft (output shaft in paragraphs 0028 and 0029)
55a, 55b Input gear (output gears in paragraphs 0028 and 0029)
62 Output shaft 65 Output gear 100, 200 Low backlash gear device

Claims (4)

A main gear connected to the shaft and a sub gear provided coaxially and provided with at least one hemispherical hole, a ball fitted into the hemispherical hole, and a size capable of fitting the ball A grooved plate having a V-shaped circumferential cross section, connected to the shaft and movable in the axial direction, a nut screwed into the shaft, and an elastic body provided between the nut and the driven plate With
In order from one end of the shaft, the nut, elastic body, driven plate, ball, sub gear, main gear are arranged,
In the driven plate, the deepest part of the hemispherical hole into which the ball of the sub gear is fitted and the deepest part of the groove are displaced in the rotation direction, and the ball is in contact with one inclined surface of the groove. In the state, pressed by the elastic body ,
The ball moves in a direction that eliminates a positional shift between the deepest portion of the hemispherical hole and the deepest portion of the groove, and generates a torsion torque in the main gear and the sub gear to reduce backlash. And
Low backlash gear mechanism.   2. A driven flange mounted on the sub-gear with a screw and having a hemispherical hole into which at least one of the balls fits and a slotted oval hole for inserting the screw. Low backlash gear mechanism. An input gear or an output gear provided on the input shaft or the output shaft, and an output gear or an input gear having two gears meshed with the input gear or the output gear and provided on the output shaft or the input shaft,
One of the output gear and the input gear is the main gear, and the other gear is the sub gear. The low backlash gear mechanism according to claim 1 or 2 is incorporated in the output gear or the input gear. Rush gear device. An input gear provided on the input shaft, an output gear provided on the output shaft, an intermediate output gear provided between the input gear and the output gear, and meshing with the input gear, and an intermediate input gear meshing with the output gear, Comprising a first intermediate gear and a second intermediate gear;
The intermediate input gear of the first intermediate gear or the second intermediate gear is the main gear or sub gear, the intermediate output gear is the sub gear or the main gear, and the first intermediate gear or the second intermediate gear is defined in claim 1 or A low backlash gear device incorporating two low backlash gear mechanisms.

Images