JP5473791B2 - Reduction gear - Google Patents

Description

  The present invention relates to a speed reduction device that eliminates backlash during stoppage and reduces image blur due to external force, while ensuring backlash during rotation and performing smooth rotational drive with a low load.

For example, when the control target is a monitoring camera, the conventional reduction gear is configured as follows.
(1) One stepping motor per axis that drives the rotation mechanism (2) One worm per axis that is rotated by the stepping motor (3) Gear holder that supports the worm and worm wheel via a bearing (4) Gear holder By the combination of (1) to (4) above, the worm wheel supported by the worm and meshed with the worm, the rotation is transmitted to the worm when the stepping motor rotates, and the output shaft rotates by decelerating with the worm wheel. Usually, the speed reducer configured as described above can rotate the surveillance camera up, down, left and right by using two output shafts in directions orthogonal to each other.
In the reduction gear configured by the worm and the worm wheel, backlash, that is, backlash of the gear, is necessary to prevent the gear from interfering with the distance between the shafts and the gear error and increasing the load.

  However, when this decelerator is applied to a surveillance camera device installed outdoors, there is a problem that rotational vibration occurs in the output shaft within the range of backlash due to disturbances such as wind, and camera image shake occurs. Further, there is a problem that positioning accuracy is lowered because the output shaft rotates within the range of backlash.

In order to avoid such problems, various means for eliminating backlash have been devised. For example, in Patent Document 1, two worms are fitted to one worm wheel, the two worms are connected by one timing belt and rotated synchronously, and the backlash is adjusted by adjusting the rotational phase of the two worms during assembly. Configured to remove.
Japanese Patent Laid-Open Publication No. 2003-228932 is configured to remove the backlash by controlling the distance between the worm and the worm wheel with an actuator and pressing the worm against the worm wheel when stopped.

Japanese Patent Application Laid-Open No. 64-46043 JP 2006-46590 A

However, in the method disclosed in Patent Document 1, it is necessary to leave a minute backlash in order to absorb the backlash fluctuation caused by the fluctuation of the backlash due to the worm wheel and the worm gear cutting accuracy and the temperature fluctuation. There is.
In addition, the method disclosed in Japanese Patent Laid-Open Publication No. 2005-228561 has problems such as a complicated structure and a reduced rigidity in the rotation direction of the output shaft due to the provision of a movable mechanism for the distance between the axes. There exists a subject that it is not necessarily suitable for applying to a reduction gear.

  The present invention has been made to solve the above-described problems. In a surveillance camera drive mechanism using a speed reducer composed of a worm and a worm wheel, the backlash at the time of stopping is eliminated, and an image is generated by an external force. An object of the present invention is to provide a speed reducer capable of reducing fluctuation and ensuring backlash during operation and performing smooth rotational driving at a low load.

The speed reducer according to the present invention includes a worm wheel that is fitted with two worms and decelerates and rotates by rotation of the worm, an output shaft that rotates by rotation of the worm wheel and rotates a control target, and each worm. The motor rotates two worms in the same direction when stopping the output shaft, and stops the two output worms when rotating the output shaft. It is characterized by rotating a fixed amount in a direction opposite to the rotating direction when the two worms are secured, ensuring a backlash between the two worms and the worm wheel, and then rotating the two worms in opposite directions .

According to the present invention, since it is configured as described above, the worm wheel is fitted with two worms and decelerated by the rotation of the worm, and the output shaft that rotates by the rotation of the worm wheel and rotates the controlled object. And an electric motor that rotates each worm individually . When stopping the output shaft, the electric motor rotates the two worms in the same direction, and when rotating the output shaft, the two worms are rotated. Rotate a certain amount in the direction opposite to the rotation direction when stopping the output shaft, secure the backlash between the two worms and the worm wheel, and then rotate the two worms in the opposite directions to operate At times, rotate the two worms while maintaining a position where the backlash can be secured, and perform smooth rotational drive with low load. Omuhoiru rotates in a direction around the reverse direction eliminating backlash, it is possible to reduce the shaking of the image by an external force.

It is a perspective view which shows the structure of the monitoring camera apparatus which uses the deceleration device which concerns on Embodiment 1 of this invention. It is a perspective view which shows the structure of the reduction gear device which concerns on Embodiment 1 of this invention. It is a figure explaining stop operation | movement of the speed reducer which concerns on Embodiment 1 of this invention. It is a figure which shows the backlash at the time of the stop operation | movement of the speed reducer which concerns on Embodiment 1 of this invention. It is a figure explaining the starting operation of the speed reducer which concerns on Embodiment 1 of this invention. It is a figure which shows the backlash at the time of starting operation of the speed reducer which concerns on Embodiment 1 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a perspective view showing a configuration of a monitoring camera device 1 including a speed reduction device 5 according to Embodiment 1 of the present invention, and shows a case where the monitoring camera is a control target. FIG. 2 is a perspective view showing the configuration of the reduction gear 5 according to Embodiment 1 of the present invention.
As shown in FIG. 1, the monitoring camera device 1 includes a camera unit 2 on which the monitoring camera is mounted, a rotation drive unit 3 for rotating the monitoring camera up and down, left and right, and a base that serves as a base for the monitoring camera device 1. Part 4.

The rotation drive unit 3 includes two speed reduction devices 5 as shown in FIG. 2 in order to rotate the surveillance camera up, down, left and right. As shown in FIG. 1, in one speed reduction device 5, the output shaft 6 is disposed in the horizontal direction in order to rotate the camera unit 2 up and down. In the other reduction gear 5, the output shaft 6 is arranged in the vertical direction in order to rotate the rotation drive unit 3 itself to the left and right.
By using the speed reducer 5 that rotates the surveillance camera up and down and the speed reduction device 5 that rotates the rotation drive unit 3 left and right, the surveillance camera can be directed in any direction up, down, left, and right.

  As shown in FIG. 2, the reduction gear 5 includes an output shaft 6, a worm wheel 7, worms 8 and 9, timing belt pulleys 10 to 13, timing belts 14 and 15, electric motors 16 and 17, and a gear holder 18.

  Two worms 8 and 9 are fitted to a worm wheel 7 fixed to the output shaft 6. The worm 8 is configured to be rotatable when the driving force from the electric motor 16 is transmitted through the timing belt pulley 11, the timing belt 14, and the timing belt pulley 10. Similarly, the worm 9 is configured to be rotatable by transmitting the driving force from the electric motor 17 via the timing belt pulley 13, the timing belt 15, and the timing belt pulley 12.

Next, the operation of the reduction gear 5 configured as described above will be described.
FIG. 3 is a view for explaining the stopping operation of the reduction gear 5 according to Embodiment 1 of the present invention, and FIG. 4 is a view showing the backlash at that time. FIG. 5 is a view for explaining the starting operation of the reduction gear 5 according to Embodiment 1 of the present invention, and FIG. 6 is a view showing the backlash at that time.
When the rotation of the output shaft 6 is stopped, the electric motors 16 and 17 rotate the worms 8 and 9 in the K1 direction shown in FIG. Here, when both the worms 8 and 9 are right-handed worms, the teeth of the worms 8 and 9 try to move in the K2 direction by rotation in the K1 direction. Therefore, the worm wheel 7 contacts the tooth surface of the worm 9 by the left rotation by the worm 8, and contacts the tooth surface of the worm 8 by the right rotation by the worm 9. That is, as shown in FIG. 4, the rotation of the output shaft 6 can be stopped in a state where the worm wheel 7 is sandwiched between the tooth surfaces of the worms 8 and 9 without backlash (no backlash).

  On the other hand, when rotating the output shaft 6, first, the electric motors 16 and 17 rotate the worms 8 and 9 by a certain amount in the K3 direction (the direction opposite to the K1 direction) shown in FIG. By this operation, the teeth of the worms 8 and 9 are both moved in the K4 direction, and backlash occurs between the worm wheel 7 and the worms 8 and 9, as shown in FIG. Next, the electric motors 16 and 17 rotate the worms 8 and 9 in opposite directions (for example, the worm 8 is in the K1 direction and the worm 9 is in the K3 direction) at the same speed. By this operation, the worm wheel 7 rotates and the output shaft 6 can be rotated.

  Here, when the output shaft 6 is rotated, a sufficient backlash can be ensured between the worm wheel 7 and the worms 8 and 9. Therefore, the tooth surfaces of the worm wheel 7 and the worms 8 and 9 do not interfere with each other even if there is a backlash fluctuation due to the backlash periodic fluctuation or temperature fluctuation caused by the gear cutting accuracy of the worm wheel 7 or worms 8 and 9. Smooth rotation drive can be performed with a load.

  On the other hand, when stopping the rotation of the output shaft 6, the motors 16, 17 once stop the rotation of the worms 8, 9, and then rotate the worms 8, 9 by a certain amount in the K1 direction of FIG. By this operation, the rotation of the output shaft 6 can be stopped in a state where the worm wheel 7 is sandwiched between the tooth surfaces of the worms 8 and 9 without rattling.

  At this time, since the worm wheel 7 is positioned without rattling by the worms 8 and 9, the rotational vibration of the output shaft 6 due to disturbance such as wind does not occur, and the shake of the camera image can be reduced. Further, the positioning accuracy can be kept high without being affected by backlash. In order to eliminate rattling during stopping, the movable part is only in the rotational direction of the worms 8 and 9 and the distance between the shafts is fixed, so that the structure is simple. The rigidity can be increased.

  As described above, according to the first embodiment, the two worms 8 and 9 are fitted to one worm wheel 7 and the two worms 8 and 9 are individually driven to rotate. By changing the rotation direction of the two worms between when the output shaft 6 is rotating and when it is stopped, an appropriate backlash is ensured at the time of rotation and smooth rotation drive is performed at a low load. By eliminating this, it is possible to reduce image shake due to external force.

Embodiment 2. FIG.
In the first embodiment, when rotating the output shaft 6, the worms 8 and 9 are rotated by a fixed amount in the K3 direction, and when stopping the rotation of the output shaft 6, the worms 8 and 9 are rotated in the K1 direction. However, only one of the worms may be rotated.

  In this case, when rotating the output shaft 6, first, the worm 8 or worm 9 is fixed in the K3 direction shown in FIG. 5 (the direction opposite to the rotation direction K1 when the rotation of the output shaft 6 is stopped). Rotate the amount. By this operation, the rotated worm teeth move in the K4 direction, and a backlash occurs between the worm wheel 7 and the worms 8 and 9. Next, the worms 8 and 9 are rotated at the same speed in opposite directions. By this operation, the worm wheel 7 rotates and the output shaft 6 can be rotated.

  On the other hand, when stopping the rotation of the output shaft 6, after temporarily stopping the rotation of the worms 8, 9, the worm 8 or the worm 9 is rotated by a certain amount in the K1 direction shown in FIG. With this operation, the rotation of the output shaft 6 can be stopped while the worm wheel 7 is sandwiched between the tooth surfaces of the worms 8 and 9 without rattling.

  As described above, according to the second embodiment, when the output shaft 6 is rotated or stopped, only one of the worms 8 and 9 is rotated to adjust the backlash. The same effects as those of the first embodiment can be obtained.

In the first and second embodiments, when the worm 8 and / or the worm 9 is rotated in the K3 direction when the rotation of the output shaft 6 is started, the worm 8 is used when the rotation of the output shaft 6 is stopped. Although the worm 9 is rotated in the K1 direction, the worm 8 and / or the worm 9 may be rotated in the K3 direction when the rotation of the output shaft 6 is stopped.
This configuration also reverses the tooth movement direction of the worms 8 and 9 (K4 direction), but the worm wheel 7 is sandwiched between the tooth surfaces of the worms 8 and 9 without backlash (backlash). None), the rotation of the output shaft 6 can be stopped.

  In the first and second embodiments, the case where the control target of the reduction gear 5 is applied to the monitoring camera device 1 as a monitoring camera has been described. However, the present invention is not limited to this, and the same applies to other control targets. It is possible to apply.

  DESCRIPTION OF SYMBOLS 1 Surveillance camera apparatus, 2 Camera part, 3 Rotation drive part, 4 Base part, 5 Reduction gear, 6 Output shaft, 7 Worm wheel, 8, 9 Worm, 10-13 Timing belt pulley, 14, 15 Timing belt, 16, 17 Electric motor, 18 Gear holder.

Claims (1)

A worm wheel in which two worms are fitted and rotated at a reduced speed by the rotation of the worm;
An output shaft that rotates by rotation of the worm wheel and rotates a control target;
An electric motor that individually rotates each worm ,
When stopping the output shaft, the motor rotates the two worms in the same direction, and when rotating the output shaft, the two worms stop the output shaft. A speed reducer characterized by rotating a predetermined amount in a direction opposite to the rotation direction to secure a backlash between the two worms and the worm wheel, and then rotating the two worms in opposite directions .

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