JP2003278894A - Planetary decelerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized planetary decelerator with high output which is excellent in durability by improving lubricity of a gear. <P>SOLUTION: The planetary decelerator is provided with a sun gear 1 to be rotationally driven by a motor 7, an annular ring gear 3 arranged by surrounding the sun gear 1, a plurality of planet gears 2 arranged by being meshed between an outer peripheral face of the sun gear 1 and an inner peripheral face of the ring gear 3, and a carrier 4 which has a carrier pin 5 connected freely rotatably to a through-hole 2a provided to the planet gear 2 and transmits revolution movement of the planet gear 2 as rotation movement via the carrier pin 5. Further, a wall-shaped protruding part 16 surrounding a rotary shaft of the carrier 4 is provided on a face opposing to the planet gear 2 of the carrier 4 as a scattering preventing structure to prevent scattering of a lubricant 17 by centrifugal force. Also, the opposing face can be provided in a recessed shape and in various uneven shapes. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary speed reducer used for electric tools and the like, and more particularly to a technique for preventing lubricant from scattering due to centrifugal force.

[0002]

2. Description of the Related Art FIG. 11 shows an electric power tool 30 incorporating a planetary speed reducer. The electric tool 30 is composed of a motor 7 for inputting power to the planetary speed reducer, a chuck 26 for transmitting output from the planetary speed reducer, a switch 27, a storage battery 28, and the like.

FIG. 12 shows a conventional planetary speed reducer having, for example, a three-stage structure. The planetary speed reducer is configured by accommodating each member in a gear case 6, and includes a sun gear 1 rotatably driven by a motor 7 and a ring gear 3 fixed to the inner surface of the gear case 6 with a carrier 4. A plurality of supported planet gears 2 are meshed with each other and connected to form a first stage planetary reduction mechanism. In the planetary deceleration mechanism of the first stage, the carrier 4 and the planet gear 2 have a circular cross-section in which a cylindrical carrier pin 5 is provided on the planet gear 2 so as to stand from the end face of the carrier 4 toward the planet gear 2 side. Is rotatably fitted and connected to the through hole 2a. Therefore, when the sun gear 1 is rotationally driven, the planet gear 2 makes a rotation motion while sliding the through hole 2a provided in the planet gear 2 and the outer peripheral surface of the carrier pin 5 together with the outer peripheral surface of the planet gear 2. The orbital motion is performed while the inner peripheral surface of the ring gear 3 is meshed. The revolving motion of the planet gear 2 is transmitted to the carrier 4 via the carrier pin 5 as a rotational motion.

Further, the carrier 4 is meshed with the second planet gear 10 as the second stage sun gear and is connected to the second ring gear 11 and the second carrier 12 similar to the first stage to reduce the planetary deceleration of the second stage. A third planet gear 13, a third ring gear 14, and a third carrier 15 that constitute a mechanism and use the second carrier 12 as a third stage sun gear.
Are connected to form a third stage planetary reduction mechanism. The rotational motion input from the motor 7 is decelerated by being transmitted in the order of the first, second, and third planetary speed reduction mechanisms, and the rotational motion of the output shaft 9 is output.

In the planetary speed reducer as described above, a lubricant is preliminarily applied to the inner peripheral surface of the planet gear and the outer peripheral surface of the carrier pin at the time of assembly so that the planet gears provided at each stage can smoothly rotate. It must be applied to ensure the lubricity of the rotating connection. Here, it is conceivable to use rolling bearings for the planet gears, but in this case, since the planet gears increase in size, it is effective for industrial machines, but it is difficult to apply it as a planetary speed reducer with a built-in electric tool.

[0006]

In devices such as electric power tools that are required to have high output, it is required to increase the input from the motor and at the same time downsize the entire device. A method of increasing the speed reduction ratio of the planetary speed reducer is adopted. However, when the input rotation speed increases, a large amount of power is applied to the internal gears and bearings, and the rotation speed of the sun gear and planet gears also increases, so the lubricant applied to ensure lubricity is centrifugally separated. It will be scattered by force. Therefore, if you try to obtain high output with a conventional planetary speed reducer for built-in electric tools,
Since the lubricant is scattered and disappears, and it is especially difficult to replenish the lubricant to the bearings, etc., if the lubricant applied at the time of assembly is exhausted, it will wear rapidly and the durability will decrease significantly. There was a problem of being lost.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a small-sized and high-power planetary speed reducer having excellent durability by improving the lubricity of gears. is there.

[0008]

In order to solve the above-mentioned problems, the present invention provides a sun gear that is rotationally driven by a motor,
An annular ring gear that surrounds the sun gear, a plurality of planet gears that are arranged so as to mesh with the outer peripheral surface of the sun gear and the inner peripheral surface of the ring gear, and rotatably through a through hole provided in the planet gear. In a planetary speed reducer comprising a carrier having a connecting carrier pin and transmitting a revolving motion of a planet gear as a rotary motion through the carrier pin, in order to prevent the lubricant from scattering to the carrier due to a centrifugal force. It is characterized by the provision of a shatterproof structure. By doing so, the lubricant applied by the high-speed rotation of the carrier is prevented from being suddenly scattered and lost, and the lubricant is gradually supplied to the sun gear and planet gears. It is possible to prevent abrasion and improve durability.

Further, as a scattering prevention structure, it is also preferable to provide a concavo-convex shape for holding a lubricant on the surface of the carrier facing the planet gear. By doing so, a large amount of lubricant is provided on the concavo-convex shape part of the carrier. In addition to being able to hold the lubricant, it is possible to prevent the lubricant from being scattered by the high-speed rotation of the carrier due to the uneven portion serving as a resistance.

Further, it is preferable to provide a plurality of concentric groove portions around the rotation axis of the carrier as the concavo-convex shape for retaining the lubricant. By doing so, the concentric circle shape can be formed even in the carrier rotating at a high speed. Since the lubricant retained in the groove portion that forms the balance is balanced, the carrier can be rotated smoothly.

Further, it is also preferable to provide a groove portion having a spiral shape around the rotation axis of the carrier as the uneven shape for holding the lubricant. By doing so, the lubricant held in the carrier is subjected to centrifugal force. Since it gradually moves to the outer peripheral side of the carrier along the spiral groove, the lubricant can be smoothly supplied to each gear.

Further, as a scattering prevention structure, it is also preferable to provide a surface of the carrier facing the planet gear in a concave shape centering on the rotation axis of the carrier. By doing so, the planet gear or the carrier pin and the carrier are formed. Since a large amount of lubricant can be retained in the gap, the lubricant can be sufficiently supplied to each gear.

It is also preferable that the concave shape of the carrier is a substantially radial concave shape formed around the rotation axis of the carrier along a straight line connecting the rotation axis of the carrier and the rotation axis of the planet gear. By doing so, it is possible to effectively concentrate the lubricant that moves in the radial direction of the carrier by the centrifugal force on the planet gears.

Further, the surface of the carrier opposite to the surface facing the planet gear is provided in a concave shape, and the through hole for communicating the concave portion and the concave portion of the surface facing the planet gear of the carrier. Is preferably provided substantially parallel to the rotation axis. By doing so, the lubricant can be held also on a portion other than the surface of the carrier facing the planet gear, and the lubricant can be retained on the planet gear. Since the lubricant can be supplied to the facing surface side through the through hole, the total amount of the lubricant that can be held and supplied in the carrier can be increased.

Further, as a scattering prevention structure, it is also preferable to provide a wall-shaped projection portion surrounding the rotation axis of the carrier on the surface of the carrier opposed to the planet gear. It is possible to form a lubricant reservoir on the peripheral surface, prevent the lubricant from scattering due to high-speed rotation of the carrier, and supply the lubricant from the lubricant reservoir to the planet gears in particular.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the accompanying drawings. The basic structure of the planetary speed reducer of the present invention is the same as the structure already described as the prior art, and therefore description thereof will be omitted. The lubricant scattering prevention structure, which is a characteristic structure of the present invention, will be described in detail below. I will explain.

1 (a) and 1 (b) show a set of a sun gear 1, a planet gear 2, a ring gear 3 and a carrier 4 which constitute an example planetary speed reducer according to the present invention. There is. A wall-shaped projecting portion 16 that surrounds the rotation axis of the carrier 4 is provided upright in the vicinity of the outer peripheral surface of the surface of the carrier 4 facing the planet gear 2 (that is, the surface on which the carrier pin 5 is installed upright) as an example. is doing. Since the carrier 4 is often manufactured as a sintered part, the protrusion 16 can be easily formed.

The protrusions 16 stand up from three portions at substantially equal intervals on the circumference around the rotation axis of the carrier 4 so as to substantially close the gap between the adjacent planet gears 2, 2. When the grease 17 applied as a lubricant at the time of assembly scatters in the radial direction due to the centrifugal force generated by the rotation of the carrier 4, the grease is supported by the inner peripheral surface of the protrusion 16 and scattered. It is supposed to suppress. Further, a reservoir for grease 17 is formed on the inner peripheral surface of the protrusion 16, and the grease 1 applied to the planet gear 2 and the like during assembly
Even when 7 is lost, the grease 17 whose viscosity has decreased due to the heat generation of rotation is gradually replenished from the reservoir, and the lubricity is secured. Thereby, the wear of the gear is prevented and the durability of the planetary speed reducer is improved.

The projection 16 may have a wall shape whose inner peripheral surface forms an arcuate shape in plan view as shown in FIG.
As shown in FIG. 2B, the inner peripheral surface may have a wall shape having a linear shape in a plan view, or as shown in FIG. 2C, the inner peripheral surface may have a wall shape having a wavy shape in a plan view. good. Also, FIG.
As shown in (d) and (e), in the protruding portion 16 of each of the above-mentioned shapes, both side end portions are further bent inward to form a substantially U-shape in plan view, so that the grease 17 can be held easily during rotation. May be improved.

It is also preferable to provide the protrusion 16 of this example on the carrier 4 of each example described later.

FIG. 3 (a) shows a set of a sun gear 1, a planet gear 2, a ring gear 3 and a carrier 4 which constitute a planetary speed reducer according to another embodiment of the present invention. As shown in FIG. 3B, a large number of irregularities having a size of 1 to 2 mm are formed on the surface of the carrier 4 of the other example facing the planet gear 2. If grease 17 is applied to the carrier 4 during assembly, the grease 17 is held by the uneven portions,
Even when subjected to the centrifugal force of rotation, the uneven portions act as resistance to suppress scattering. Further, when the temperature rises due to the heat generated by the rotation, the viscosity of the grease 17 applied to the concavo-convex portion decreases, gradually moves in the radial direction in which centrifugal force acts, and is supplied to the tooth surface of the planet gear 2 and the bearing portion for lubrication. Sex is secured. Thereby, the wear of the gear is prevented and the durability of the planetary speed reducer is improved.

It is preferable that the region where the irregularities are formed is substantially the entire surface of the carrier 4 that faces the planet gears 2. However, the present invention is not limited to this and the size of the irregular shape of the carrier 4 is not limited to this. Is not particularly limited to 1 to 2 mm.

4 (a) and 4 (b) show a carrier 4 which constitutes a planetary speed reducer according to still another example of the embodiment of the present invention. Further, a plurality of groove portions 18 are formed concentrically around the rotation axis of the carrier 4 on the surface of the carrier 4 facing the planet gear 2 of another example. If grease 17 is applied to the carrier 4 during assembly, the grease 17 is held by the uneven portions formed by the groove portions 18, and scattering due to centrifugal force of rotation is suppressed. Since the groove portion 18 is concentric with the rotation axis of the carrier 4 as a center, the carrier 4 smoothly rotates while keeping the balance of the grease 17 in good condition. Then, when the temperature rises due to the heat generated by the rotation, the viscosity of the grease 17 applied to the concave and convex portions of the groove 18 decreases and gradually moves in the radial direction in which the centrifugal force acts to supply the tooth surface of the planet gear 2 and the bearing portion. Is
Lubricity is secured. Thereby, the wear of the gear is prevented and the durability of the planetary speed reducer is improved.

Since the centrifugal force becomes greater as it moves away from the rotation axis, it is necessary to form the groove 18 deeper as it moves away from the rotation axis of the carrier 4, as shown in FIG. 5C. Although desirable for prevention, it is not particularly limited thereto. Further, it is effective for holding the grease 17 that the groove portion 18 is formed over substantially the entire surface of the carrier 4 facing the planet 2. However, the shape is not particularly limited to this, and the cross-sectional shape of the groove portion 18 is also possible. It may have a rectangular cross section shown in FIGS. 5A and 5C, a substantially U-shaped cross section shown in FIG. 5B, or any other shape.

FIGS. 6A and 6B show the case where the groove portion 18 is formed in a spiral shape around the rotation axis of the carrier 4. In this way, the groove portion 18 is formed from the center side to the outer peripheral side. With the continuous spiral shape, when the carrier 4 rotates, the grease 17 gradually flows toward the outer peripheral side along the groove portion 18 by the centrifugal force, and the grease 17 is smoothly supplied to the tooth surface of the planet gear 2 and the bearing portion. It is what is done.

7 (a) to 7 (c) show a carrier 4 which constitutes another example of a planetary speed reducer according to the embodiment of the present invention. The surface of the carrier 4 opposite to the planet gear 2 of another example is provided in a concave shape with the rotation axis of the carrier 4 as the center, and if grease 17 is applied to the concave portion of the carrier 4 during assembly. The centrifugal force of rotation can also prevent the grease 17 from scattering. Further, when the temperature rises due to the heat generated by the rotation, the viscosity of the grease 17 applied to the concave portion decreases and gradually moves in the radial direction in which the centrifugal force acts and is supplied to the tooth surface and the bearing portion of the planet gear 2.
Lubricity is secured. Thereby, the wear of the gear is prevented and the durability of the planetary speed reducer is improved. In addition,
The planet ring 2 is positioned so that its end is housed in the concave outer peripheral side portion of the carrier 4, as shown in FIG.
As shown in (a) to (c), the planet ring 2 may be positioned so as not to be housed in the concave portion of the carrier 4.

The concave portion of the carrier 4 is shown in FIG.
As shown in (a) to (c), it is provided in a substantially radial shape in three directions around the rotation axis of the carrier 4 so as to be formed along a straight line connecting the rotation axis of the carrier 4 and the rotation axis of the planet gear 2. May be. As a result, when the grease 17 gradually moves in the radial direction by the centrifugal force of rotation, the planet gear 2
Since the grease is concentratedly supplied to the bearing portion of, the grease 17 can be efficiently supplied to the bearing portion of the planet gear 2 where it is difficult to supply the grease 17, and the lubricity can be ensured. In addition,
The radial concave portion as described above is not limited to a radial shape corresponding to the number of planet gears 2,
A plurality of linear grooves may be formed radially around the rotation axis of the carrier 4.

10 (a) to 10 (c) show a carrier 4 constituting a planetary speed reducer according to still another example of the embodiment of the present invention. Further, the carrier 4 of another example has substantially the same configuration as the planet gear 4 of another example described above, but has a characteristic configuration that is opposite to the surface (hereinafter, referred to as the surface) of the carrier 4 facing the planet gear 2. A concave portion is also formed on the surface (hereinafter referred to as the back surface), and a through hole 19 for communicating the concave portions on the front and back surfaces is formed substantially parallel to the rotation axis of the carrier 4. The through hole 19 is formed integrally with the mounting hole 20 provided in the carrier 4 for inserting and fixing the carrier pin 5, and the base portion of the carrier pin 5 with the carrier pin 5 attached. The communication hole 19 is located at.

The concave portion is not limited to the substantially radial shape as shown in FIG.

If grease 17 is applied to the concave portions on the front and back surfaces of carrier 4 during assembly, splashing of grease 17 due to the centrifugal force of rotation is suppressed and the temperature rises due to the heat generated by rotation. As a result, the viscosity of the grease 17 applied to the concave portions on both the front and back surfaces gradually decreases and gradually moves in the radial direction in which centrifugal force acts, and the grease 17 retained in the concave portions on the front surface becomes It is supplied to the bearing to ensure lubricity. Further, the grease 17 held in the concave portion of the back surface is supplied to the root portion of the carrier pin 5 in the concave portion of the front surface through the through hole 19 to ensure the lubricity of the planet gear 2, particularly the bearing portion. According to this structure, it is possible to increase the total amount of the grease 17 held in advance on the carrier 4, prevent wear of the gears further, and improve the durability of the planetary speed reducer.

By providing the through hole 19 at the base portion of the carrier pin 5 as described above, it is easy to form the through hole 19 integrally with the mounting hole 20, but it may be formed at another place. Also,
Also in the present example, the number of through holes 19 is three at each of the positions corresponding to each of the carrier pins 5, but the number is not limited to this.

The structure of the planetary type planetary speed reducer has been described above based on the embodiments. However, the same structure is not limited to the planetary speed reducer having the three-stage structure described in the prior art, but a single-stage planetary speed reducer. It is also suitable to be applied to a planetary speed reducer having a structure or another multi-stage structure, or a star type or solar type planetary speed reducer.

[0033]

As described above, according to the first aspect of the present invention, the lubricant applied is prevented from being suddenly scattered and lost by the high speed rotation of the carrier, and the lubricant is gradually applied to the sun gear and planet gears. Since the lubricant is supplied, there is an effect that the rapid wear of each gear can be prevented and the durability can be improved.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, a large amount of lubricant can be held in the uneven portion of the carrier, and the uneven portion There is an effect that it becomes resistance and it is possible to prevent the lubricant from scattering due to the high speed rotation of the carrier.

According to the invention of claim 3, in addition to the effect of the invention of claim 2, in the carrier rotating at a high speed, the lubricant held in the concentric groove portions is well balanced. Therefore, there is an effect that the carrier can be smoothly rotated.

According to the invention of claim 4, in addition to the effect of the invention of claim 2, the lubricant held in the carrier is gradually rotated by centrifugal force along the spiral groove to form the outer periphery of the carrier. By moving to the side, there is an effect that the lubricant can be smoothly supplied to each gear.

According to the invention of claim 5, in addition to the effect of the invention of claim 1, a large amount of lubricant can be retained in the gap between the planet gear or the carrier pin and the carrier. There is an effect that the lubricant can be sufficiently supplied to each gear.

According to the invention of claim 6, in addition to the effect of the invention of claim 5, the lubricant moving in the radial direction of the carrier by centrifugal force is effectively concentrated on the planet gears. There is an effect that can be.

Further, in the invention described in claim 7, in addition to the effect of the invention described in claim 5 or 6, it is possible to retain the lubricant on a portion of the carrier other than the surface facing the planet gear. In addition, since the lubricant can be supplied to the surface facing the planet gear through the through hole, there is an effect that the total amount of the lubricant that can be held and supplied in the carrier can be increased. .

Further, in the invention described in claim 8, in addition to the effect of the invention described in any one of claims 1 to 7, a lubricant reservoir is formed on the inner peripheral surface of the wall-shaped protrusion. Therefore, it is possible to prevent the lubricant from scattering due to the high-speed rotation of the carrier and to supply the lubricant from the lubricant reservoir to the planet gears in particular.

[Brief description of drawings]

FIG. 1 shows a main part of an example planetary speed reducer in an embodiment of the present invention, (a) is a schematic front view, and (b) is a schematic perspective view.

FIG. 2 is an explanatory view showing a protrusion of the above carrier,
(A) is a projection in which the inner peripheral surface has a substantially arc shape in plan view,
(B) is a protrusion when the inner peripheral surface is linear in plan view,
(C) is a protrusion when the inner peripheral surface is in the shape of a wave in plan view, (d)
(A) shows a protrusion when both ends of the protrusion are bent inward, and (e) shows a protrusion when both ends of the protrusion shown in (b) are bent inward.

3A and 3B show another example of a planetary speed reducer according to an embodiment of the present invention, FIG. 3A is a schematic front view of a main part, and FIG. 3B is a schematic perspective view of a carrier.

FIG. 4 shows a carrier of a planetary speed reducer according to still another example of the embodiment of the present invention, in which (a) is a schematic front view,
(B) is a schematic perspective view.

5A is a cross-sectional view taken along the line AA of FIG. 4A, in which FIG. 5A shows a groove having a rectangular cross section, FIG. 5B shows a groove having a U-shaped cross section, and FIG. This is the case when the depth is uneven.

6A and 6B show a carrier in the case where the above groove portion is provided in a spiral shape, in which FIG. 6A is a schematic front view and FIG. 6B is a schematic perspective view.

FIG. 7 shows a main part of a planetary speed reducer according to another example of the embodiment of the present invention, in which (a) is a schematic front view, (b) is a schematic perspective view, and (c) is B in (a). It is a -B line sectional view.

FIG. 8 shows a main part when the planetary gears of the planetary speed reducer of the same are arranged differently, (a) is a schematic front view, (b) is a schematic perspective view, and (c) is (a). 6 is a cross-sectional view taken along the line CC of FIG.

FIG. 9 shows a main part when the concave portion of the planetary speed reducer is substantially radial, (a) is a schematic front view,
(B) is a schematic perspective view, (c) is the DD sectional view taken on the line of (a).

FIG. 10 shows a main part of a planetary speed reducer according to still another example of the embodiment of the present invention, in which (a) is a schematic front view,
(B) is a schematic perspective view, (c) is the EE sectional view taken on the line of (a).

FIG. 11 is a side view showing the electric power tool.

FIG. 12 is a sectional view showing a conventional planetary speed reducer incorporated in an electric power tool.

[Explanation of symbols]

1 Sun Gear 2 planet gears 2a through hole 3 ring gear 4 career 5 carrier pins 7 motor 16 Projection 17 Grease 18 Groove 19 through holes

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Claims (8)

[Claims] 1. A sun gear rotatably driven by a motor, an annular ring gear surrounding the sun gear, and a plurality of planet gears meshed with each other between an outer peripheral surface of the sun gear and an inner peripheral surface of the ring gear. And a carrier that has a carrier pin that is rotatably connected to a through hole provided in the planet gear and that transmits the revolving motion of the planet gear as a rotary motion through the carrier pin. A planetary reduction gear characterized in that a carrier is provided with a scattering prevention structure for preventing scattering of the lubricant due to centrifugal force. 2. The planetary speed reducer according to claim 1, wherein, as a scattering prevention structure, a concavo-convex shape for holding a lubricant is provided on a surface of the carrier facing the planet gear. 3. The planetary speed reducer according to claim 2, wherein the concavo-convex shape for holding the lubricant is provided with a plurality of concentric groove portions centering on the rotation axis of the carrier. 4. The planetary speed reducer according to claim 2, wherein the concavo-convex shape for holding the lubricant is provided with a groove portion having a spiral shape around the rotation axis of the carrier. 5. The planetary speed reducer according to claim 1, wherein, as the scattering prevention structure, a surface of the carrier facing the planet gear is provided in a concave shape centering on a rotation axis of the carrier. 6. The concave shape of the carrier is a substantially radial concave shape formed around the rotation axis of the carrier along a straight line connecting the rotation axis of the carrier and the rotation axis of the planet gear. The planetary speed reducer according to claim 5. 7. A through hole for providing a surface of the carrier opposite to a surface facing the planet gear in a concave shape and allowing the concave portion and a concave portion of the surface facing the carrier of the carrier to communicate with each other. 7. The planetary speed reducer according to claim 5, wherein is provided substantially parallel to the rotation axis. 8. The planetary deceleration according to claim 1, wherein a wall-shaped protrusion that surrounds a rotation axis of the carrier is provided on a surface of the carrier facing the planet gear, as the scattering prevention structure. Machine.