JP2003166602A - Worm wheel rotation transmission method and worm gear rotation transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a backlash and prevent disengagement of a worm and a worm wheel even under an overload via a simple mechanism, and simplify the backlash adjusting operation as a skilled operation. <P>SOLUTION: The worm is provided with a worm support mechanism of low rigidity in a normal direction to the worm wheel and extremely high rigidity in a tangential direction, and springs are disposed to energize the worm in a normal direction to the worm wheel, so that tooth surfaces are continuously brought into close contact. When force acting in a radial direction on each of the gears is generated by a runout of rotary shafts or the like, the gears are ensured that they rotate always maintaining contact of the tooth surfaces. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to backlash removal in a rotation transmission mechanism using a worm wheel.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIG. FIG. 3 is an exploded perspective view showing a configuration of a conventional worm wheel rotation transmission mechanism. Worm 21 is a warm base
It is rotatably attached to the shaft 22 via a bearing 23, one end of which is fixed to the rotary shaft of a motor 24, which is a power source, and serves as the input side of this rotation transmission mechanism. The worm wheel 25 is attached to the rotary shaft 26, and the rotary shaft 26 is rotatably attached to the worm wheel base 27 via a bearing, and is the output side of the rotation transmission mechanism. The bearing of this rotary shaft 26 is attached to the worm wheel base 27 below the worm wheel 25, so it is hidden and not visible in FIG.

The worm base 22 is attached to the worm wheel base 27 by a fixing bolt 28 with an axial distance 29 (see FIG. 4). The mounting holes for the worm base 22 are elongated holes in the axial direction (direction of the axial distance 29). By mounting the worm base 22 at any position on the worm wheel base 27, the axial distance 29
Can be adjusted. Worm 21 and worm wheel 25 mesh at a position determined by the mounting position of worm base 22.

FIG. 4 shows a worm wheel 25 and a worm.
FIG. 21 is a schematic diagram for explaining a meshing relationship with 21.
The distance 29 between the shafts is determined by the position of the fixing bolt 28 for fixing the worm base 22 and the worm wheel base 27, and the place where the mounting hole 30 of the worm base 22 is fixed. When the rotation transmission mechanism shown in FIG. 3 is operated, there is rotational runout due to the processing accuracy and assembly accuracy of the component parts. Therefore, when the worm and the worm wheel rotate, the clearance on the tooth surface is not uniform due to the position of the worm and the worm wheel. Instead, there is a place where the backlash is small and the engagement is deep as shown in FIG. 6, and a place where the backlash is large and the engagement is shallow as shown in FIG.

In a place where the backlash is small as shown in FIG. 6, the frictional force is large and smooth rotation cannot be obtained.
Further, in a place where the backlash is large as shown in FIG. 5, there is a problem such that there is backlash, the positioning accuracy is deteriorated, and the shaking at the time of stop becomes large. To absorb this, a smooth rotation is obtained, and the worm base is adjusted to a position where optimal backlash is achieved with minimum backlash.
Fix 22. In addition, lapping work such as lapping was performed to reduce backlash.

[0006]

As described above, a slight clearance is required between the tooth flanks for the rotation transmission mechanism of the worm and the worm wheel to rotate smoothly. This is to absorb the processing accuracy and assembly accuracy of the worm and the rotation transmission mechanism to which the worm wheel is attached. If the assembly is performed without the gap, the frictional force on the tooth surface increases, a large rotational force is required, and in the worst case, the rotation becomes impossible. In addition, the wear of the tooth surface progresses and the gap increases. In a device that requires precise positioning, this slight gap (backlash) becomes a problem.
The occurrence of such backlash is improved by stopping from the same direction at the time of stop. However, if an external force acts after the stop, position shift occurs. Moreover, when the external force is vibration, there is a problem such as shaking. In order to eliminate this sway, it was necessary to add a brake mechanism that operates after stopping to the outside.

In a rotation transmission mechanism using a worm and a worm wheel, a force acts on the tooth surface in three directions of an axial direction, a tangential direction, and a normal direction when viewed from the worm. In order to reduce the backlash of the rotation transmission mechanism, the distance between the shafts should be adjusted narrowly before assembly. However, if the distance between the shafts is made too small, it is impossible to absorb the machining accuracy of gears and the like and the runout of rotation due to an assembly error, and smooth rotation cannot be performed. Various backlash removal mechanisms have been proposed to improve this, but there were problems such as the structure being complicated and expensive, and the engagement between the worm and the worm gear being disengaged when a large external force was applied. .

An object of the present invention is to eliminate the above problems, remove the backlash with a simple mechanism, and prevent disengagement between the worm and the worm gear even if an excessive load is applied. Another object of the present invention is to simplify the backlash adjustment work which was a skilled work.

[0009]

In order to achieve the above object, the worm wheel rotation transmission device of the present invention is caused by a worm and a runout of rotation of the worm wheel.
A worm support mechanism with low rigidity in the normal direction of the worm wheel and extremely high rigidity in the tangential direction is provided on the worm so as to eliminate the tooth flank in the normal direction. The tooth surface is kept in close contact by providing a spring that presses against each other, and when a force acting in the radial direction of the gears of each other acts due to the deflection of the rotating shaft, it moves so as to follow this force, so the tooth surface is always in contact. It is possible to rotate while keeping the above, and it is possible to achieve both removal of backlash and smooth rotation.

The worm wheel rotation transmitting method of the present invention is a worm wheel rotation transmitting device for transmitting rotational power by a worm and a worm wheel, wherein the worm wheel has elasticity in a normal direction and rigidity in a tangential direction. The worm is supported by an iter spring having, and the axial distance between the worm and the worm wheel is kept within a predetermined range by following the force in the normal direction acting on the tooth surfaces of the worm and the worm wheel. It is a thing.

The worm wheel rotation transmission device of the present invention is a worm wheel rotation transmission device for transmitting rotational power by a worm and a worm wheel, wherein the worm has elasticity in a normal direction of the worm wheel and is tangential to the worm wheel. Is provided with a support unit that supports a high degree of rigidity, and keeps the axial distance between the worm and the worm wheel within a predetermined range by following the force in the normal direction acting on the tooth surfaces of the worm and the worm wheel. To hold.

The support unit of the rotation transmitting device for a worm wheel according to the present invention includes worm bearings provided at both shaft ends of the worm, a worm base for holding the worm bearings, and a worm provided for the worm wheel. A wheel bearing, a worm wheel base that holds the worm wheel bearing, and a parallel italy spring attached to the worm wheel base and the worm base and extending in the axial direction of the worm, the parallel ita spring being the worm base and the worm base. It is arranged between the worm wheel bases so that a spring force is generated in the normal direction of the worm wheel. Further, in the worm wheel rotation transmission device of the present invention, a stopper for limiting the movement amount of the worm wheel in the normal direction is further provided on the worm base so that the inter-axis distance does not move more than a predetermined distance. Is.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is an exploded perspective view showing the configuration of the rotation transmission mechanism of the first embodiment of the present invention. Warm one is
It is rotatably attached to the worm base 2 via a bearing 3. One end of the worm base 2 is fixed to the rotating shaft of a motor 4 which is a power source and serves as an input side of the reduction mechanism. The worm wheel 5 is attached to the rotating shaft 6, and the rotating shaft 6 is rotatably attached to the worm wheel base 7 via a bearing (not shown) and is the output side of the reduction gear mechanism.

The worm base 2 is composed of a pair of leaf springs 8
The tooth flanks of the worm wheel base 7 are in close contact with each other via the, and the backlash is zero. Since the worm base 2 is supported only by a pair of iter springs 8, it has a high supporting rigidity in the axial and tangential directions of the worm 1 but is elastic only in the normal direction and acts on the tooth surface. It follows the normal force and moves while maintaining contact with the tooth surface.

The spring force of the iter spring 8 is selected according to the normal direction force, which is one of the forces in three directions acting on the tooth surface, which is obtained from the transmission force. Therefore, according to the speed reduction mechanism of FIG. 1, even if there is a slight rotational runout in each gear, it is absorbed by the spring force, so that the close contact state of the tooth surfaces is maintained and the backlash is removed to achieve a smooth rotational operation. realizable.

An embodiment of the present invention will be described with reference to FIG. FIG. 2 is a perspective view showing the configuration of the second embodiment of the present invention. The first embodiment described with reference to FIG. 1 has a space-efficient structure in which the iter spring 8 serves both to support the worm base 2 and to absorb the normal force due to its elasticity. However, depending on the application, it is expected that a normal force exceeding the elastic limit of the Itabune 8 will act, and in this case, the elasticity of the Itabune 8 will be lost. In the second embodiment, in addition to the first embodiment, the ball plunger 9 is installed in the same plane as the radial force acting on the tooth surface.

FIG. 7 is a sectional view showing the structure of the ball plunger 9 according to the embodiment of the present invention described with reference to FIG. The ball plunger 9 has a coil spring 10 housed inside a cylinder with an external thread, and at the tip of the cylinder, a metal ball 11 is housed as a contact in a movable state by the coil spring 10 according to an external force. There is. The ball plunger 9 is fixed at a position where a metal ball comes into contact with the worm base 2 and a spring force is applied thereto by an external screw structure and a fixing nut 12.

Since the movable range due to rotational runout is as small as several tens of microns, the operating stroke of the metal ball 11 is also small.
1 mm or less is sufficient. When a force is applied in the radial direction due to an unexpected external force, the cylindrical portion of the ball plunger 9 comes into contact with the worm base 2 and this acts as a stopper to prevent the iter spring 8 from deforming beyond its elastic limit. As a result, the function of supporting the movable state in the normal direction can be limited to the iter spring 8, and the function of absorbing the displacement due to the normal direction force is the coil spring 10 in the ball plunger 9.
Therefore, a more appropriate spring force can be selected.

Further, the ball plunger 9 is attached to the worm.
Since it can be installed on the same plane as the rotation axis of 1,
It is possible to eliminate the moment force applied to the ita-spring 8 and the worm base 2 can follow the radial force more smoothly. Although the ball plunger 9 is used in this description, another object having an elastic force may be used. Further, a stopper for restricting the operating range of the worm base 2 may be provided separately.

[0020]

With this mechanism, both reduction of backlash and smooth rotational movement can be achieved, and frictional force between tooth flanks is reduced, so that the progress of wear of tooth flanks can be delayed and the life of gears can be extended. it can. Also, in the past, an assembly adjustment by an expert was required to achieve both backlash reduction and smooth rotation, but since spring force is responsible for backlash adjustment, it is possible to assemble with almost no adjustment, reducing the assembly time. Can be realized. With the revolving device for surveillance cameras installed outdoors, the image taken with a high-magnification lens, even with a slight backlash, could shake when exposed to wind or vibration, making the screen difficult to see. Solvable.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a second embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration of a conventional worm gear reduction mechanism.

FIG. 4 is a view for explaining a meshing relationship between a conventional worm wheel and a worm.

FIG. 5 is a view for explaining a meshing relationship between a conventional worm wheel and a worm.

FIG. 6 is a view for explaining a meshing relationship between a conventional worm wheel and a worm.

FIG. 7 is a sectional view showing the structure of a ball plunger 9 according to an embodiment of the present invention.

[Explanation of symbols]

1: worm, 2: worm base, 3: bearing,
4: Motor, 5: Worm wheel, 6: Rotation axis,
7: Worm wheel base, 8: Ita spring, 9: Ball plunger, 10: Coil spring, 11: Metal ball, 12:
Fixing nut, 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 axes.

Claims (4)

[Claims] 1. A worm wheel rotation transmission device for transmitting rotational power by a worm and a worm wheel, wherein the worm is supported by an iter spring having elasticity in a normal direction of the worm wheel and rigidity in a tangential direction, A worm wheel rotation transmission method characterized in that the axial distance between the worm and the worm wheel is kept within a predetermined range by following the force in the normal direction acting on the tooth surfaces of the worm and the worm wheel. 2. A worm wheel rotation transmission device for transmitting rotational power by means of a worm and a worm wheel, comprising a support unit for supporting the worm elastic in a normal direction of the worm wheel and highly rigid in a tangential direction. A worm wheel rotation transmission characterized in that the axial distance between the worm and the worm wheel is kept within a predetermined range by following the force in the normal direction acting on the tooth surfaces of the worm and the worm wheel. apparatus. 3. The worm wheel rotation transmission device according to claim 2, wherein the support unit includes worm bearings provided at both shaft ends of the worm, a worm base holding the worm bearings, and the worm wheel. A worm wheel bearing, a worm wheel base that holds the worm wheel bearing, and a parallel italy spring attached to the worm wheel base and the worm base and extending in the axial direction of the worm, wherein the parallel italy spring is the worm base. And a worm wheel base, the worm wheel rotation transmitting device being arranged so that a spring force is generated in a direction normal to the worm wheel. 4. The worm wheel rotation transmission device according to claim 3, further comprising:
A worm wheel rotation transmission device, wherein the worm base is provided with a stopper that limits a movement amount of the worm wheel in a normal direction.