JP2007092903A - Worm gear rotation transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make removal of backlash compatible with suppression of coming-off of meshing of gears because run-out of rotation due to limit of machining precision and assembly error of the gear cannot be absorbed and smooth rotation cannot be achieved if the distance between axes of a worm and a worm wheel is too small, although the distance between axes must be adjusted to make it small and they must be assembled to reduce backlash. <P>SOLUTION: A rotation transmission mechanism using the worm and the worm wheel is constituted in such a way that the worm wheel has elasticity in the direction of its normal line. The worm is pressed against the worm wheel for assembly to remove backlash, achieve smooth rotation, and suppress coming-off of meshing of gears. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to backlash removal in a worm gear rotation transmission mechanism.

  The gear mechanism is indispensable for transmitting rotational motion. At this time, there is a worm gear as a gear mechanism suitable for a case where a large reduction ratio is required. The worm gear is a gear mechanism that includes a worm and a worm wheel meshed with the worm.

The conventional worm gear technology will be described with reference to FIG. FIG. 3 is a perspective view showing a configuration of an example of a conventional worm gear transmission mechanism.
FIG. 3 shows a worm 21 and a worm wheel 25 engaged therewith. First, the worm 21 is rotatably attached to the worm base 22 by a bearing 23, and a rotary shaft of a motor 24 as a power source is connected to one end of the worm 21. It is the input side of the driving force of the transmission mechanism.
On the other hand, the worm wheel 25 is provided with a rotating shaft 26, and this rotating shaft 26 is rotatably held by a worm wheel base 27 via a bearing, and serves as an output side of the driving force of the rotation transmission mechanism. .
The bearing of the rotary shaft 26 is attached to the lower worm wheel base 27 of the worm wheel 25 and is not visible in FIG.

At this time, the worm base 22 is attached to the worm wheel base 27 by a fixing bolt 28 while maintaining an inter-axis distance 29 (described later). The worm 21 and the worm wheel 25 are engaged with each other at an inter-axis distance determined by the mounting position of the worm base 22 at this time.
For this reason, the mounting hole formed in the worm base 22 so that the fixing bolt 28 can be inserted has a long hole shape or an elliptical shape that is elongated in the inter-axis direction (direction of the inter-axis distance 29). By fixing the worm base 22 at an arbitrary position of the wheel base 27, the distance between the axes can be adjusted. This is for optimizing the backlash, that is, the gap that exists between the gears and causes play.

  FIG. 4 is a schematic diagram for explaining the meshing relationship between the worm wheel 25 and the worm 21, and an inter-axis distance 29 is shown in this figure. The inter-axis distance 29 is determined depending on where the fixing bolt 28 for attaching the worm base 22 to the worm wheel base 27 is fixed in the attachment hole provided in the worm base 22.

  For example, if the worm gear rotation transmission mechanism shown in FIG. 3 is operated and the worm 21 and the worm wheel 25 are rotated, the gaps between the meshing tooth surfaces of the worm 21 and the worm wheel 25 are not uniform. The gap changes depending on the position of the worm wheel 25, and as shown in FIG. 5, there is a place where the meshing is shallow and the backlash is large, and a place where the meshing is deep and the backlash is small as shown in FIG. It will appear.

  This is due to the occurrence of rotational runout in the worm 21 and the worm wheel 25 due to limitations in the processing accuracy and assembly accuracy of the component parts. At this time, in the place where the backlash shown in FIG. 5 becomes large, a problem such as a looseness and a deterioration in positioning accuracy and a large shaking at the time of stop occurs. On the other hand, as shown in FIG. In a place where is small, there is a problem that the frictional force becomes large and smooth rotation cannot be obtained.

  In order to absorb this, conventionally, when fixing the worm base 22 to the worm wheel base 27, the worm base 22 can be adjusted to the mounting position so that smooth rotation can be obtained and the optimum meshing can be achieved with the minimum backlash. In order to improve the processing accuracy of 21 and worm wheel 25, a lapping operation such as lapping was performed. Such adjustment work requires skill and requires a long time for the work.

On the other hand, apart from these methods, a method of holding back the worm elastically against the worm wheel and eliminating backlash has been proposed as a prior art (see, for example, Patent Document 1).
JP 2004-108443 A

  In the above prior art, no consideration has been given to an increase in frictional force due to the elastic pressing of the worm against the worm wheel and a decrease in positioning force at the time of stopping, and there has been a problem in reducing transmission efficiency and improving positioning accuracy. .

  In the rotation transmission mechanism using the worm and worm wheel, force is applied to the tooth surface in the axial direction, tangential direction, and normal direction with respect to the tooth surface during power transmission. However, a slight gap is required between the tooth surfaces, as described above, because of the limited processing accuracy and assembly accuracy of the rotation transmission mechanism to which the worm and worm wheel are attached. To absorb.

  Therefore, in order to reduce the backlash in the rotation transmission mechanism using the worm and the worm wheel, it is necessary to adjust the distance between the worm and the worm wheel so that the distance between the axes is reduced. If it is too much, the limit of processing accuracy of gears and the like and the runout of rotation due to assembly errors cannot be absorbed, and smooth rotation cannot be obtained.

If it is assembled without gaps here, the frictional force of the tooth surface increases, a large rotational force is required, and in the worst case, rotation is impossible. In addition, in this case, the tooth surface wears quickly, and the backlash increases in a short time.
On the other hand, in the case of a device that requires precise stop positioning, the presence of backlash reduces positioning accuracy, so even a slight backlash causes a problem. However, in this case, it is possible to improve the problem caused by backlash by stopping at the same rotational direction at the time of stopping.However, even in this case, if an external force is applied after stopping, a position shift occurs. When the external force is vibration, there are problems such as shaking. In order to eliminate such displacement and shaking, it is necessary to separately add a brake mechanism that operates after stopping, which complicates the configuration.

  At this time, according to the above-described prior art, it is possible to cope with these problems. However, in this prior art, when a large external force is applied, the worm and the worm wheel may be disengaged. In order to cope with this disengagement, when the force when elastically pressing the worm against the worm wheel is increased, as described above, the frictional force increases and a large rotational force is required. In the worst case, the rotation becomes impossible and the tooth surface wears quickly, resulting in a problem that the backlash increases in a short time.

Therefore, in the prior art, an increase in frictional force due to the elastic pressing of the worm against the worm wheel and a decrease in the positioning force at the time of stopping are contradictory, and as described above, the transmission efficiency is lowered and the positioning accuracy is improved. Will cause problems.
An object of the present invention is to provide a worm gear rotation transmission device capable of achieving both the elimination of backlash and the suppression of disengagement of gears.

In order to achieve the above object, in the worm gear rotation transmission device of the present invention, the worm wheel is configured to have elasticity in the normal direction thereof, and the worm is pressed against the worm wheel for assembly. In addition, the backlash can be removed and the rotation can be smoothly performed, and the gear can be prevented from being disengaged.
That is, by pressing and assembling, it is possible to remove the tooth surface gap (backlash) between the worm and the worm wheel, and to rotate while always contacting the tooth surface. In addition, because the worm wheel has elasticity, it can absorb excessive force on the tooth surface by absorbing the external force due to the elasticity of the worm wheel, even if misalignment or rotational fluctuation occurs due to the processing accuracy or assembly accuracy of the component parts. Smooth rotation without giving is possible.

Preferably, the worm gear rotation transmission device according to claim 1 is a worm gear rotation transmission device that transmits rotational power by the worm and the worm wheel, the worm wheel having elasticity in the normal direction, and the worm and worm wheel The backlash is removed by keeping the axial distance between the worm and the worm wheel within a predetermined range following the normal force acting on the tooth surface.
A worm gear rotation transmission device according to a second aspect is the worm gear rotation transmission device according to the first aspect, wherein the worm gear rotation transmission device includes a sleeve having elasticity, and the worm wheel is attached to the outer periphery of the sleeve. The backlash is eliminated by maintaining the distance between the shafts of the worm wheel and the worm wheel within a predetermined range.
The worm gear rotation transmission device according to claim 3 is the worm gear rotation transmission device according to claim 2, wherein the base for fixing the sleeve is provided with a bearing, and the bearing is the normal force applied to the sleeve. The worm and the worm wheel are prevented from being disengaged when an excessive load is applied.

According to the present invention, according to the present invention, it is possible to achieve both the backlash removal and the smooth rotation operation, and the frictional force between the tooth surfaces is reduced. Can be extended. Further, the gears are not disengaged.
In addition, according to the present invention, since the backlash adjustment work, which is a skillful work, can be simplified, the assembly cost can be reduced.

Hereinafter, the worm gear rotation transmission device according to the present invention will be described in detail with reference to the illustrated embodiments. First, FIG. 1 is a sectional view showing a first embodiment of a worm gear rotation transmission mechanism according to the present invention. It is.
In FIG. 1, a worm 1 is held on a worm base 4 by a bearing (not shown), and is thereby rotatably attached to the worm base 4. A motor (not shown) is a power source at one end of the shaft. (Not)) is connected, and this is on the input side of the driving force for the gear mechanism. At this time, the motor is attached to the worm base 4.

Next, the worm wheel 2 is attached to the outer peripheral portion of the sleeve 3. The sleeve 3 serves as a rotation axis (rotation center axis 16 is indicated by a one-dot chain line), and the rotation axis is held on the worm wheel base 5 via the bearing 6 so that the sleeve 3 can rotate with respect to the worm wheel base 5. This is the output side of this rotation transmission mechanism.
Here, the driving force by the worm wheel 2 is used as a driving source when the imaging direction of the surveillance camera is changed (panning operation or tilting operation), for example.

The bearing retainer 7 and the inner ring spacer 8 are parts for attaching the sleeve 3 to the worm wheel base 5 and are fixed to the worm wheel base 5 by adjusting the machining dimensions so as to apply pressure to the bearing 6. Yes.
The worm base 4 is fixed to the worm wheel base 5 so that the worm 1 is pressed against the worm wheel 2 and the tooth surfaces of the worm base 4 are in close contact with each other and the backlash is zero (in FIG. 1 and the like, the worm base 4 and the worm base 4 The mounting part is omitted.)

The sleeve 3 has elasticity in the normal direction of the worm wheel 2, and the worm wheel 2 is fixed to the sleeve 3. For this reason, since it is fixed to the sleeve 3 having a case where there is a rotational runout caused by the processing accuracy and assembly accuracy of the component, even if there is a rotational runout caused by the processing accuracy and assembly accuracy of the component, the sleeve 3 It can be absorbed by its own elasticity. Accordingly, it is possible to follow the force in the normal direction of the worm wheel 2 and maintain the close contact of the tooth surfaces.
For example, the shape of the sleeve 3 is a shape corresponding to a normal force acting on the tooth surface of the worm wheel 2.
As described above, in the worm gear rotation transmission mechanism of the present embodiment, it is possible to perform a smooth rotational motion while removing backlash.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a sectional view showing a second embodiment of the worm gear rotation transmission mechanism according to the present invention.
This embodiment has a structure in which a bearing 10 is added along the inner periphery of the sleeve 3 of the worm wheel 2 installation portion in the configuration of the first embodiment. The content described in FIG. 1 is omitted, and only the additional part from FIG. 1 will be described below.
In FIG. 2, the upper portion symmetrical to the rotation center axis 16 is omitted.

The bearing 10 is fixed to the bearing block 9 on the inner ring side by a bearing retainer 11.
The bearing block 9 is fixed to the worm wheel base 5 ′, and an adjustment allowance is provided for fixing the bearing block 9 so as to adjust in the normal direction of the worm wheel 2 (that is, in FIG. 3). This is equivalent to adjusting the inter-axis distance 29).

As in the description of the embodiment of FIG. 1, the worm base 4 is fixed by pressing the worm 1 against the worm wheel 2. For this reason, the sleeve 3 after attachment is in an elastically deformed state.
The amount of elastic deformation of the sleeve 3 changes variously during one rotation of the worm wheel 2 due to rotational deflection.
The bearing block 9 has a structure that is fixed so as to come into contact with the inner periphery of the sleeve 3 at a portion where the elastic deformation amount of the sleeve 3 is maximum.

In the embodiment of FIG. 1, a smooth rotation transmission operation without backlash is possible. However, in the first embodiment, when a large external force is applied to the worm gear rotation transmission mechanism, the amount of elastic deformation of the sleeve 3 temporarily increases, the mesh between the worm 1 and the worm wheel 2 is disengaged, and a rotational deviation occurs. There is a possibility that.
In order to prevent this, in the embodiment of FIG. 2, the bearing 10 is provided inside the sleeve 3 so that the distance between the worm 1 and the worm wheel 2 is not more than a certain distance, and the tooth surface is disengaged. It is preventing.

  As described above, the worm gear rotation transmission mechanism according to the second embodiment of the present invention enables smooth rotational movement while removing backlash, and even when a large external force is temporarily applied. And the tooth surface of the worm wheel will not be disengaged.

FIG. 7 shows a third embodiment of the present invention. In both the first and second embodiments, the sleeve (the sleeve 3 in FIG. 1 or 2) is fixed to the outer ring side of the bearing (the bearing 6 in FIG. 1 or 2). However, as shown in FIG. 7, the sleeve 3 'may be held on the inner ring side of the bearing 6'.
In FIG. 7, as in FIG. 2, the upper portion symmetrical to the rotation center axis 16 is omitted.

Furthermore, in the embodiments described so far, the worm wheel is made elastic, and the sleeve is installed inside the worm wheel, but elasticity may be added by another structure.
For example, the worm wheel may have a double structure, and a worm wheel having elasticity only in the normal direction may be formed by connecting the worm wheel with an elastic material and fixing the worm wheel in a direction other than the normal direction.

  Further, for example, in order to give elasticity, as shown in a cross-sectional view for explaining an embodiment of the present invention shown in FIG. 8, the direction of the line of force of the sleeve supporting the worm wheel of the present invention (the direction of the alternate long and short dash line 18) Is shifted to a position that is not in line with the force in the normal direction (the direction of the alternate long and short dash line 17) at the position of the tooth surface that meshes with the worm, for example, the cross section is arranged in a U-shape.

  As described above, according to the present invention, both removal of backlash and smooth rotation operation can be achieved, and the frictional force between the tooth surfaces is reduced, so that the progress of tooth surface wear is delayed and the life of the gear is shortened. Can be extended.

Sectional drawing which shows the structure of the 1st Embodiment of this invention. Sectional drawing which shows the structure of the 2nd Embodiment of this invention. The perspective view which shows the structural example of the conventional worm gear rotation transmission apparatus. The schematic diagram for demonstrating the meshing condition by a worm gear mechanism. The figure for demonstrating the backlash example by a worm gear mechanism. The figure for demonstrating the backlash example by a worm gear mechanism. Sectional drawing which shows the structure of the 3rd Embodiment of this invention. Sectional drawing for demonstrating one Embodiment of this invention.

Explanation of symbols

  1: Worm, 2: Worm wheel, 3, 3 ': Sleeve, 4: Worm base, 5, 5', 5 ": Worm wheel base, 6, 6 ': Bearing, 7, 7': Bearing retainer, 8, 8 ′: Inner ring spacer, 9: Bearing block, 10: Bearing, 11: Bearing retainer, 16: Rotation center shaft, 21: Worm, 22: Worm base, 23: Bearing, 24: Motor, 25: Worm wheel, 26: Rotating shaft, 27: Worm wheel base, 28: Fixing bolt, 29: Distance between shafts.

Claims (3)

In the worm gear rotation transmission device that transmits the rotational power by the worm and the worm wheel, the worm wheel has elasticity in the normal direction, and the normal direction force acting on the tooth surface of the worm and the worm wheel. A worm gear rotation transmission device that follows and removes backlash by maintaining the distance between the worm and the worm wheel within a predetermined range. 2. The worm gear rotation transmission device according to claim 1, further comprising an elastic sleeve, wherein the worm wheel is attached to an outer periphery of the sleeve, and an elastic distance between the worm and the worm wheel is set to a predetermined distance between the worm and the worm wheel. A worm gear rotation transmission device characterized by removing backlash by holding in a range. The worm gear rotation transmission device according to claim 2, wherein a bearing is provided on a base for fixing the sleeve, and the bearing disperses the force in the normal direction applied to the sleeve and an excessive load is applied. A worm gear rotation transmission device characterized in that the worm and the worm wheel are sometimes prevented from being disengaged.

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