JP7115876B2 - Eccentric oscillating reduction gear - Google Patents

Description

The present invention relates to an eccentric oscillating speed reducer.

BACKGROUND ART Conventionally, there has been proposed an eccentric oscillating speed reducer that includes an external gear, an internal gear that meshes with the external gear, and an eccentric body that oscillates the external gear. In this type of speed reducer, the pin member forming the internal teeth of the internal gear and the internal gear body may be separated from each other, and the pin member may be rotatably arranged in a pin groove provided in the internal gear body. be. As such a speed reducer, Patent Document 1 discloses one using an internal gear body made of an aluminum alloy.

JP 2016-128723 A

The inventors of the present invention have proposed a new method in which, as in Patent Document 1, when an internal gear body made of an aluminum alloy is used, the amount of wear in the pin grooves greatly increases depending on the amount of Si in the internal gear body. I got some insight.

An aspect of the present invention has been made in view of such circumstances, and one of the objects thereof is to provide a technique capable of preventing an increase in the amount of wear of pin grooves when using an internal gear body made of an aluminum alloy. That's what it is.

One aspect of the present invention relates to an eccentric oscillating speed reducer, which includes an eccentric oscillating speed reducer including an external gear, an internal gear that meshes with the external gear, and an eccentric body that oscillates the external gear. wherein the internal gear has an internal gear body provided with a pin groove and a pin member rotatably arranged in the pin groove, and the internal gear body contains Si It is composed of an aluminum alloy with an amount of 6.0% by weight or more.

According to the present invention, when an internal gear body made of an aluminum alloy is used, it is possible to prevent an increase in wear of the pin grooves.

1 is a side cross-sectional view showing an eccentric oscillating speed reducer according to an embodiment; FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1; FIG. 4 is a diagram for explaining lost motion; 4 is a graph showing the relationship between the lost motion of the speed reducer and the operating time obtained by performing a predetermined endurance test.

Hereinafter, in the embodiments and modified examples, the same constituent elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Moreover, in each drawing, for convenience of explanation, some of the constituent elements are appropriately omitted, and the dimensions of the constituent elements are shown by appropriately enlarging or reducing them.

First, the structure of the speed reducer according to the embodiment will be described, and then the background leading to the idea of the speed reducer according to the embodiment will be described.

FIG. 1 is a side cross-sectional view showing an eccentric oscillating speed reducer 10 (hereinafter also simply referred to as a speed reducer 10) of the embodiment. The reduction gear 10 mainly includes an input shaft 12 , an eccentric body 14 , an external gear 16 , an internal gear 18 , carriers 20 and 22 and a casing 24 . The speed reducer 10 oscillates the external gear 16 meshing with the internal gear 18 to cause one of the external gear 16 and the internal gear 18 to rotate, and the resulting motion component is driven from the output member. Output to device. Hereinafter, the direction along the central axis La of the internal gear 18 will be referred to as the "axial direction", and the circumferential direction and the radial direction of a circle centered on the central axis La will be referred to as the "circumferential direction" and the "radial direction", respectively. do.

The input shaft 12 is rotatable around the rotation center line by rotational power input from a driving device (not shown). The speed reducer 10 of the present embodiment is a center crank type in which the rotation center line of the input shaft 12 is coaxial with the center axis line La of the internal gear 18 . The drive device is, for example, a motor, gear motor, engine, or the like.

The eccentric body 14 is provided so as to be rotatable integrally with the input shaft 12 . The input shaft 12 functions as a crankshaft with an eccentric 14 . The eccentric body 14 has its own axis eccentric with respect to the rotation center line of the input shaft 12, and is capable of causing the external gear 16 to oscillate. The speed reducer 10 of this embodiment has a plurality of eccentric bodies 14, and the phases of the eccentric bodies 14 are out of phase with each other. In this embodiment, two eccentric bodies 14 are provided, and the phases of adjacent eccentric bodies 14 are shifted by 180°.

The external gear 16 is individually provided corresponding to each of the plurality of eccentric bodies 14 . The external gear 16 is rotatably supported by the corresponding eccentric body 14 via the eccentric bearing 26 .

The internal gear 18 is provided radially outside the plurality of external gears 16 and meshes with the external gears 16 . FIG. 2 is a cross-sectional view taken along line AA of FIG. As shown in FIGS. 1 and 2 , the internal gear 18 includes an internal gear body 30 provided with a plurality of pin grooves 28 and a first gear rotatably supported by the pin grooves 28 of the internal gear body 30 . and a pin member 32 .

The internal gear body 30 has a tubular shape as a whole, and a plurality of pin grooves 28 are formed in the inner peripheral portion of the internal gear body 30 . The plurality of pin grooves 28 are formed at intervals in the circumferential direction, and have cross-sectional shapes that allow the first pin members 32 to be fitted therein. The first pin member 32 of this embodiment has a cylindrical shape, and the pin groove 28 has an arcuate cross-sectional shape into which the first pin member 32 can be fitted.

The first pin member 32 is individually provided corresponding to each of the plurality of pin grooves 28 and rotatably arranged in the corresponding pin groove 28 . The first pin member 32 forms internal teeth of the internal gear 18 . The number of internal teeth of the internal gear 18 (the number of first pin members 32) is one more than the number of external teeth of the external gear 16 in this embodiment.

Detachment of the first pin member 32 in the radial direction is restricted by a detachment restricting member 34 arranged radially inside the first pin member 32 . Although the detachment restricting member 34 of the present embodiment is the external gear 16 , a separate member from the external gear 16 may be configured.

As shown in FIG. 1 , axial displacement of the first pin member 32 is restricted by displacement restricting members 36 arranged on both sides of the first pin member 32 in the axial direction. The displacement restricting member 36 of the present embodiment is an outer ring of the main bearing 42 to be described later, but may be configured by a separate member from the outer ring of the main bearing 42 .

The carriers 20 , 22 are arranged on the axial sides of the external gear 16 . Carriers 20 and 22 include a first carrier 20 arranged on one side of the external gear 16 in the axial direction and a second carrier arranged on the other side of the external gear 16 in the axial direction. 22 are included. The carriers 20 and 22 are disk-shaped and rotatably support the input shaft 12 via an input shaft bearing 38 . The first carrier 20 and the second carrier 22 are connected via a plurality of second pin members 40 . The second pin member 40 axially penetrates the plurality of external gears 16 at positions radially offset from the axis of the external gear 16 . A part of the second carrier 22 constitutes the second pin member 40 of the present embodiment, but a separate member from the second carrier 22 may constitute the second pin member 40 .

The casing 24 has a tubular shape as a whole, and the external gear 16 is arranged inside thereof. The casing 24 of this embodiment also serves as the internal gear body 30 and is integrated with the internal gear body 30 .

A member that outputs rotational power to the driven device is referred to as an output member, and a member that is fixed to an external member for supporting the speed reducer 10 is referred to as a fixed member. The output members of this embodiment are the carriers 20 and 22 and the fixed member is the casing 24 . The output member is rotatably supported by the fixed member via a main bearing 42 . The main bearings 42 are rolling bearings and are arranged between the carriers 20 , 22 and the casing 24 .

The operation of the above reduction gear 10 will be described. When rotational power is transmitted from the driving device to the input shaft 12, the eccentric body 14 of the input shaft 12 rotates around the rotation center line passing through the input shaft 12, and the eccentric body 14 causes the external gear 16 to oscillate. At this time, the external gear 16 oscillates so that its own axis rotates around the rotation center line of the input shaft 12 . When the external gear 16 oscillates, the meshing positions of the external gear 16 and the internal gear 18 are sequentially displaced. As a result, each time the input shaft 12 makes one rotation, one of the external gear 16 and the internal gear 18 rotates by the amount corresponding to the difference in the number of teeth between the external gear 16 and the internal gear 18 .

When the carriers 20 and 22 are the output members and the casing 24 is the member to be fixed as in this embodiment, the external gear 16 rotates. On the other hand, when the casing 24 is the output member and the carriers 20 and 22 are the fixed members, the internal gear 18 rotates. The output member rotates in synchronization with the rotation component of the external gear 16 or the internal gear 18 to output the rotation component to the driven device. At this time, the rotation of the input shaft 12 is reduced by a reduction ratio corresponding to the difference in the number of teeth between the external gear 16 and the internal gear 18, and then output to the driven device.

Next, the background that led to the idea of the reduction gear 10 of this embodiment will be described. The speed reducer 10 may use an aluminum alloy for the internal gear body 30 for the purpose of reducing its weight. When the internal gear body 30 made of an aluminum alloy is used in this way, the present inventor believes that the amount of wear of the pin grooves 28 of the internal gear body 30 is large, depending on the amount of Si in the aluminum alloy, as described below. We have found that there are cases where it increases.

Specifically, the inventor measured the lost motion of the reduction gear transmission under conditions in which the amount of Si in the internal gear body 30 was varied. The term "lost motion" as used herein refers to a response delay that occurs when the direction of rotation of the input shaft 12 is reversed. The lost motion measurement method will be explained.

FIG. 3 is a diagram for explaining lost motion. When the input shaft 12 is fixed and a torque is applied to the output members (carriers 20, 22 in the embodiment), an axial twist approximately proportional to the torque is generated between the input shaft 12 and the output members. . When torque is applied to the output member in the range from 0 to rated torque x (±100%) and the torque is removed, the torque and torsion angle are measured to obtain a hysteresis curve Lh as shown in FIG. be done. The lost motion is represented by the sum of the absolute values of the median value Ac1 of the torsion angle of the hysteresis curve at the rated torque x 3% and the median value Ac2 of the torsion angle of the hysteresis curve at the rated torque x -3%.

Lost motion is used as one of indices indicating the degree of wear of the components of the reduction gear transmission 10 . Below, the degree of wear of the pin groove 28 of the internal gear body 30 was evaluated using this lost motion.

FIG. 4 is a graph showing the relationship between the lost motion of the speed reducer 10 and the operating time obtained by the following endurance test. In this endurance test, the speed reducers 10 with substantially the same lost motion before the start of operation and with different amounts of Si in the internal gear body 30 were used. The first pin member 32 is made of an iron-based material (bearing steel (SUJ2)).

In this endurance test, the speed reducer 10 is repeatedly operated over a plurality of cycles, with the operations performed in the order of start operation (acceleration operation) → constant speed operation → stop operation (deceleration operation) within a predetermined cycle time as one cycle. let me drive In starting operation and stopping operation of the speed reducer 10, rotational power was input to the input shaft 12 to rotate the output member so that a predetermined peak torque was applied to the input shaft 12 and the output member. The lost motion of the speed reducer 10 obtained through this endurance test and the accumulated operating time in all cycles in the endurance test were evaluated. At this time, the lost motion of the reduction gear 10 was measured after waiting for the entire reduction gear 10 heated through the endurance test to cool to the same temperature as the ambient room temperature (25° C.).

Details of components A to G of the internal gear body 30 shown in FIG. 4 are as shown in Table 1 below. In FIG. 4, together with the notation of components A to G, the amount of Si is written together in parentheses. The balance of the aluminum alloy of each component listed in Table 1 is Al and unavoidable impurities. In this specification, the contents of aluminum alloy components in terms of weight percent are simply expressed as "%".

As shown in FIG. 4, when the Si content of the internal gear body 30 is less than 6.0%, the lost motion tends to greatly increase in a short period of time regardless of the Si content. On the other hand, when the Si content of the internal gear body 30 is 6.0% or more, compared to the case where the Si content is less than 6.0%, the amount of increase in lost motion over time is significantly increased even if the operating time is increased. You can understand that it will be smaller. In particular, when the Si content of the internal gear body 30 is 7.0% or more, it can be understood that the amount of increase in lost motion over time can be further reduced without being significantly affected by the Si content.

Further, the inventor disassembled the speed reduction gear 10 subjected to the test, and visually confirmed whether the pin groove 28 of the internal gear body 30 was damaged. As a result, when the Si content is less than 6.0%, damage occurs in the pin grooves 28 in the speed reducer 10 of any component A to C, and when the Si content is 6.0% or more, any component D It was confirmed that the pin grooves 28 of the reduction gears 10 of 1 to 10 had no or very few scratches. This is because when the amount of Si is less than 6.0%, the wear amount of the pin grooves of the internal gear body 30 greatly increases, and when the amount of Si is 6.0% or more, the increase in the amount of wear can be suppressed. means that there are

In addition, the inventor visually confirmed whether the first pin member 32 was damaged in addition to the pin groove 28 of the internal gear body 30 . As a result, it was confirmed that, when the Si content was less than 6.0%, not only the pin groove 28 of the internal gear body 30 but also the first pin member 32 was damaged. This is because the wear of the pin groove 28 increases the surface roughness of the inner wall surface thereof, and the first pin member 32 is worn when the first pin member 32 comes into contact with the portion with the large surface roughness. guessed. It has also been confirmed that such damage to the first pin member 32 does not occur when the Si content is 6.0% or more.

As described above, when the Si content of the internal gear body 30 is 6.0% or more, it is possible to prevent a situation in which the amount of wear of the pin grooves 28 of the internal gear body 30 greatly increases. Moreover, when the Si content of the internal gear body 30 is 6.0% or more, an increase in the amount of wear of the first pin member 32 as well as the pin groove 28 of the internal gear body 30 can be avoided. By preventing an increase in the amount of wear of the pin groove 28 of the internal gear body 30 and the first pin member 32 in this manner, the durability of the reduction gear transmission 10 can be improved.

Based on the above findings, the internal gear body 30 of the embodiment is conditioned to be made of an aluminum alloy having a Si content of 6.0% or more. From the viewpoint of avoiding an increase in the wear amount of the pin groove 28, the Si content of the aluminum alloy is preferably 7.0% or more. This condition is also set based on the measurement results shown in FIG. The upper limit of the Si content is not particularly limited, but if it is excessively large, there is a concern that the machinability will deteriorate. From this point of view, the Si content is preferably 24.0% or less.

Components other than Si in the aluminum alloy and numerical ranges are not particularly limited, and may be set to known components and numerical ranges, for example. The components other than Si and the numerical range may include, for example, Cu, Mg, Zn, Fe, and Ni components described below, and the balance may be composed of Al and unavoidable impurities. It should be noted that the components described below include the case where the numerical value of the component referred to is 0, that is, the case where the component referred to is not actually contained.

Cu contributes to securing the hardness of the aluminum alloy by age hardening. On the other hand, if the amount of Cu is excessive, the corrosion resistance is adversely affected, so the Cu content is preferably 5.0% or less. Specifically, it is preferably 4.0% or less for aluminum alloys for casting, and 5.0% or less for aluminum alloys for die casting.

Mg contributes to ensuring mechanical strength. On the other hand, if the amount of Mg is excessive, there is concern that the elongation will decrease, so the Mg content is preferably 1.5% or less. Specifically, it is preferably 1.5% or less for aluminum alloys for casting, and 0.65% or less for aluminum alloys for die casting.

Zn contributes to the improvement of fluidity. On the other hand, an excessive amount of Zn adversely affects corrosion resistance, so the Zn content is preferably 3.0% or less. Specifically, it is preferably 1.0% or less for aluminum alloys for casting, and 3.0% or less for aluminum alloys for die casting.

Fe is preferably 1.3% or less. Specifically, it is preferably 1.0% or less for aluminum alloys for casting, and 1.3% or less for aluminum alloys for die casting.

Ni contributes to ensuring high-temperature strength. On the other hand, if the amount of Ni is excessive, the corrosion resistance is adversely affected, so the Ni content is preferably 1.5% or less. Specifically, it is preferably 1.5% or less for aluminum alloys for casting, and 0.55% or less for aluminum alloys for die casting.

In addition, at least one of the components Ti, Mn, Pb, Sn, and Cr may be contained in a content as described below. Ti is preferably 0.3% or less. Specifically, it is preferably 0.2% or less for aluminum alloys for casting, and 0.3% or less for aluminum alloys for die casting. Mn is preferably 0.65% or less. Specifically, it is preferably 0.6% or less for aluminum alloys for casting, and 0.65% or less for aluminum alloys for die casting. Pb is preferably 0.35% or less. Specifically, it is preferably 0.2% or less for aluminum alloys for casting, and 0.35% or less for aluminum alloys for die casting. Sn is preferably 0.3% or less. Specifically, it is preferably 0.1% or less for aluminum alloys for casting, and 0.3% or less for aluminum alloys for die casting. Cr is preferably 0.2% or less. Specifically, it is preferably 0.2% or less for aluminum alloys for casting, and 0.15% or less for aluminum alloys for die casting.

In addition, components used for improvement treatment such as Na, Sr, Sb, and P may be contained in the range of 0.05% or less for individual components and 0.15% or less in total.

The internal gear body 30 having the aluminum alloy composition described above is obtained by melting a raw material containing similar components and casting the melted raw material. This casting method is not particularly limited, and a gravity casting method, a die casting method, or the like is used. Further, it does not matter whether or not the cast product obtained by casting is subjected to heat treatment.

The first pin member 32 of this embodiment is made of an iron-based material. The ferrous materials here include bearing steel, cast iron, etc., in addition to steel such as chromium molybdenum steel. When the first pin member 32 is made of a ferrous material, it is easier to secure the mechanical strength of the first pin member 32 than when made of an aluminum alloy. On the other hand, since the hardness of the first pin member 32 made of ferrous material is much higher than the hardness of the internal gear body 30 made of aluminum alloy, the pin groove 28 of the internal gear body 30 is likely to be worn. . Even under this premise, the wear of the internal gear body 30 can be reduced by setting the Si content of the aluminum alloy constituting the internal gear body 30 to 6.0% or more (preferably 7.0% or more). It has the advantage of preventing

Exemplary embodiments of the present invention have been described above in detail. All of the above-described embodiments merely show specific examples for carrying out the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of constituent elements can be made without departing from the spirit of the invention defined in the claims. It is possible. In the above-described embodiment, descriptions such as "of the embodiment", "in the embodiment", etc. are added to the contents that allow such design changes. Changes are not unacceptable. Moreover, the hatching attached to the cross section of the drawing does not limit the material of the hatched object.

Although the eccentric oscillating speed reducer of the embodiment has been described as an example of the center crank type, the type is not particularly limited. For example, it may be applied to a distribution type eccentric oscillating speed reducer in which a plurality of input shafts 12 (crankshafts) having eccentric bodies 14 are arranged at positions offset from the central axis of the internal gear 18 .

An example in which the output members of the embodiment are the carriers 20 and 22 and the fixed member is the casing 24 has been described. Alternatively, the output member may be the casing 24 and the fixed members may be the carriers 20,22.

An example in which the internal gear body 30 of the embodiment also serves as the casing 24 and is integrated with the casing 24 has been described. Alternatively, the internal gear body 30 may be provided separately from the casing 24 or may be rotatably supported with respect to the casing 24 .

DESCRIPTION OF SYMBOLS 10... Eccentric oscillation type|mold reduction gear, 10... Reduction gear, 14... Eccentric body, 16... External gear, 18... Internal gear, 28... Pin groove, 30... Internal gear main body, 32... Pin member.

Claims (4)

an external gear; and
an internal gear that meshes with the external gear;
An eccentric oscillating reduction gear including an eccentric body that oscillates the external gear,
The internal gear has an internal gear body provided with a pin groove, and a pin member rotatably arranged in the pin groove,
The internal gear body is an eccentric oscillating speed reducer made of an aluminum alloy containing 6.0% by weight or more of Si. 2. The eccentric oscillating type reduction gear transmission according to claim 1, wherein said aluminum alloy has a Si content of 7.0% by weight or more. 3. The eccentric oscillation type reduction gear transmission according to claim 1, wherein said aluminum alloy has a Si content of 24.0% by weight or less. 4. The eccentric oscillating type reduction gear transmission according to claim 1, wherein said pin member is made of a ferrous material.

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