JP2582485Y2 - Worm reduction gear - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a worm speed reducer, which is suitably used in small motors for automobiles, etc., in which lubrication to the worm speed reducer is difficult, and aims at improving the efficiency of the worm speed reducer and extending its life. is there.

[0002]

2. Description of the Related Art Conventionally, in a small motor for an automobile such as a wiper motor, a worm gear is integrally formed on a motor output shaft, or a worm gear shaft is connected to a motor output shaft.
A worm speed reducer that transmits the rotational force by meshing the worm gear with a worm wheel is used.

[0003] Since the sliding surfaces of the worm gear and the worm wheel are rubbed, grease lubrication is generally performed. However, with grease lubrication, when viewed microscopically, grease cannot be held on the sliding surface, and the worm gear and the worm wheel are in simple contact with each other, so that the friction coefficient increases and the transmission efficiency of rotational force increases. There was a problem of bad.

In order to solve the above-mentioned problem, Japanese Patent Application Laid-Open No. Sho 59-179540 has proposed a gear material made of a material having a small friction coefficient, such as oil-impregnated plastic.

[0005]

However, the above-mentioned oil-impregnated plastics generally have insufficient strength and heat resistance, so that there is a problem that the strength and heat resistance of the gear deteriorate.

[0006] In order to solve the above problem, there has been proposed a method in which a reinforcing fiber such as a glass filler is mixed with an oil-impregnated plastic material to improve strength and heat resistance. (JP-A-58-77964)

However, when an oil-impregnated plastic material mixed with reinforcing fibers such as the filler is used, abrasion of the surface of the mating member to be brought into sliding contact becomes remarkably large, which causes a problem that the life of the worm reduction gear is shortened.

The present invention is intended to solve the above-mentioned conventional problems, and maintains good lubrication of the sliding surfaces of the worm gear and the worm wheel, and reduces wear of the sliding surfaces (tooth surfaces). The purpose is to extend the service life and achieve efficient transmission of torque.

[0009]

That is, according to the present invention, at the sliding contact portion where the worm gear and the worm wheel are in sliding contact with each other, at least one of the tooth surface of the worm gear and the tooth surface of the worm wheel has an opening edge. Has a closed shape, and is provided with a plurality of long groove-shaped fine oil sump grooves extending in a direction intersecting with the sliding direction of the worm gear and the worm wheel. To provide.

The oil sump groove is formed in a narrow band shape extending in a direction perpendicular to the sliding direction. Further, when the traveling direction of the worm gear is one direction, it is preferable that the worm gear be formed in a shape that is inclined toward the center from both sides with respect to the traveling direction and is bent into a mountain shape.

[0011]

According to the present invention, at least one of the tooth surfaces of the worm gear and the worm wheel that are in sliding contact with each other,
Since a plurality of fine grooves are provided, the lubricating oil brought into this sliding contact surface is stored in these fine grooves, the amount of oil between the sliding contact surfaces increases, and the tooth surface is constantly During this time, the lubricating oil is held and the pressure becomes high. Therefore, the sliding surfaces of the worm gear and the worm wheel are in a state of fluid lubrication, the sliding friction coefficient is reduced, and the transmission efficiency can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. As shown in FIG. 1, the worm device of the embodiment is applied to a wiper motor for an automobile. A worm gear 3 is fixed to an output shaft 2 of a motor 1, and a worm wheel 4 is meshed with the worm gear 3. The rotational force is transmitted from the output shaft 5 to a wiper drive mechanism (not shown).

FIGS. 2 and 3 are enlarged views of a sliding portion between the worm gear 3 and the worm wheel 4, and the worm gear 3 rotates counterclockwise as shown, and moves from right to left. The worm wheel 4 meshing with the worm gear 3 rotates counterclockwise when the teeth 10 are pushed toward the left side in the figure.

The worm gear 3 is made of metal, and the worm wheel 5 is made of a plastic material. The plastic of this embodiment is not an oleaginous plastic and is not a plastic reinforced with reinforcing fibers, but is made of a plastic having strength and heat resistance.
Further, both the worm gear and the worm wheel may be made of a plastic material. When a plastic material having strength and heat resistance is used, an oil-impregnated plastic material may be used, or a fiber-reinforced plastic or a metal material may be used.

The teeth 10 of the worm wheel 4 include:
Sliding contact surface 1 on the side pressed by teeth 11 of worm gear 3
As shown in FIGS. 4 and 5, a large number of fine strip-shaped oil reservoir grooves 12 extending long in a direction orthogonal to the direction X of sliding contact with the teeth 11 are formed in Oa. These oil sump grooves 12 are discontinuous grooves whose opening edges form a closed shape as shown in the figure, and discontinuous portions 13 are provided alternately between the oil sump grooves 12.

The depth of the oil sump groove 12 is preferably about several μm or less, and the pitch P between the grooves arranged in parallel is preferred.
Is preferably at least twice the groove width W.

By providing the above-mentioned oil sump groove 12, the lubricating oil caught on the sliding surface can be removed from the oil sump groove 12.
The lubricating oil stored when the tooth surface 10a slides on the tooth 11 has a high pressure, and the sliding surface between the worm gear 3 and the worm wheel 4 is in a state of fluid lubrication. As a result, the sliding friction coefficient between the worm gear 3 and the worm wheel 4 is reduced, and the rotation transmission efficiency can be improved.

Further, for example, a tooth surface 10a by a tooth 11a
Even when the pressing load becomes large, the oil film strength on the surface of the tooth surface 10a is high, so that the oil film does not break,
It is possible to prevent the moment when the tooth surface 10a comes into direct contact with the surface of the tooth 11, and to always maintain the fluid lubrication state.
Generally, in the meshing structure of the worm gear and the worm wheel, the lubricating oil easily escapes from the sliding surface. That is, paying attention to one tooth surface of the worm wheel, after sliding with the worm gear, the worm wheel separates from the worm gear due to rotation of the worm wheel. Further, the tooth surface of the worm gear is not always engaged with the worm wheel, but is engaged with the tooth surface of the worm wheel only at a certain rotational position. When the worm gear and the worm wheel separate from each other, the lubricating oil on one tooth surface is scooped by the other tooth surface in the sliding direction. Furthermore, in a state where the worm gear and the tooth surface of the worm wheel are not engaged,
Lubricating oil is easily scattered from the tooth surface due to the rotating centrifugal force and the like. However, in this embodiment, since the opening edge of the oil sump groove 12 has a closed shape and a long groove shape extending in a direction intersecting the sliding direction, the non-sliding of the worm gear 3 and the worm wheel 4 is not performed. Escape of the lubricating oil, which sometimes occurs, can be reduced to a minimum. That is, if the oil reservoir groove is merely closed, the lubricating oil is scooped out from the oil reservoir groove 12 when the worm gear 3 and the worm wheel 4 move away from each other in the sliding state. However, when the long groove-shaped oil reservoir groove 12 is extended in a direction intersecting the sliding direction, the sliding direction is not the longitudinal direction of the groove but the width direction, so that the lubricating oil is drawn out of the groove. It becomes difficult. When the worm gear 3 and the worm wheel 5 slide in the same area (sliding area), the total area of the grooves required to obtain the same friction reducing effect is a long groove crossing the sliding direction. The groove having a smaller area suffices, for example, in comparison with the case of a groove having a isotropic shape such as a circle. Therefore, with the groove shape as in the present invention, a high friction reducing effect can be obtained with a small amount of lubricating oil. Further, since the oil reservoir groove 12 is a fine groove, the effect of preventing the lubricating oil from dropping due to surface tension is high.

Since the fluid lubrication state can be maintained as described above, even when a material in which a reinforcing fiber such as a glass filler is mixed is used for a worm wheel and / or a worm gear, there is no direct contact. Can be prevented from shortening the life.

FIG. 6 shows another embodiment of the present invention, in which the shape of the oil sump groove 12 'formed on the sliding contact surface is changed.
In the second embodiment, the sliding direction (friction direction) between the worm gear and the worm wheel is only one direction indicated by an arrow X in the figure, and the oil reservoir groove 12 ′ is formed at both ends in the traveling direction of the worm gear 3. Leaning more towards the center,
In other words, it is shaped like a mountain. That is, the oil sump groove 12 ′ is formed so as to be inclined in the traveling direction from the base and the tip of the tooth surface 10 a toward the center from the base and the tip thereof, and this mountain-shaped groove is formed similarly to the first embodiment. Formed discontinuously.

The lubricating oil trapped in the sliding contact surface provided with the oil sump groove 12 'is actively collected at the center of the sliding contact surface, and the oil pressure in the central portion is increased to further increase the lubrication. It is possible to improve the performance and reduce the wear of the contact surface.

In each of the above-described embodiments, the oil reservoir groove is formed on the tooth surface of the worm wheel. However, the oil reservoir groove may be provided on the tooth surface of the worm gear.
Oil sump grooves may be provided on both tooth surfaces of the worm gear and the worm wheel.

[0023]

As is apparent from the above description, in the worm reduction gear according to the present invention, a large number of fine oil sump grooves are formed on at least one of the sliding contact surfaces of the tooth surfaces of the worm gear and the worm wheel that mesh with each other. The lubricating oil is provided in the oil sump groove, so that the lubricating oil can be reliably supplied to the sliding contact surface, and fluid lubrication can be realized by the lubricating oil. Therefore, the rotational force can be transmitted efficiently and the friction coefficient on the sliding contact surface is reduced,
Long life can be achieved by reducing the amount of friction. In addition, since the opening edge of the oil sump groove has a closed shape, when the worm gear and the worm wheel slide, the pressure of the lubricating oil in the oil sump groove increases and lubricity is improved. Further, since the lubricating oil is stored in the fine oil sump groove, the escape of the lubricating oil generated when the worm gear and the worm wheel do not slide can be minimized. Furthermore, since the oil sump groove is a long groove extending in a direction intersecting the sliding direction of the worm gear and the wheel, a high friction reducing effect can be obtained with a small amount of lubricating oil.

[Brief description of the drawings]

FIG. 1 is a sectional view of a wiper motor including a worm speed reducer according to the present invention.

FIG. 2 is an enlarged view of a sliding portion between a worm wheel and a worm gear of FIG.

[Fig. 3]

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is a sectional view of FIG.

FIG. 6 is a view similar to FIG. 3, showing another embodiment of the present invention.

[Explanation of symbols]

 3 Worm gear 4 Worm wheel 12 Oil sump groove

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 55/22 F16H 1/16 H02K 7/116

Claims (3)

(57) [Scope of request for utility model registration] An opening is formed in at least one of a tooth surface of the worm gear (3) and a tooth surface of the worm wheel (4) at a sliding contact portion where the worm gear (3) and the worm wheel (4) are in sliding contact with each other. The edge has a closed shape, and a plurality of long groove-shaped fine oil reservoir grooves (12) extending in a direction intersecting the sliding direction of the worm gear (3) and the worm wheel (4) are provided. A worm wheel reduction device characterized by the above-mentioned. 2. The worm reduction gear according to claim 1, wherein the oil sump groove is formed in a narrow band shape extending in a direction perpendicular to a sliding direction. 3. The oil reservoir groove (12) has a shape that, when the traveling direction of the worm gear (3) is one direction, inclines toward the center from both sides with respect to the traveling direction and breaks into a mountain shape. The worm speed reducer according to claim 1, wherein the worm speed reducer is formed.