JP2561143B2 - Casing mounting structure for planetary gear unit - Google Patents

Description

The present invention relates to a casing mounting structure for a planetary gear device.

The planetary gear device has a wide range of applications as a speed reducer or a speed increaser.

Planetary gear sets are fixed to the casing in many applications.

For example, a planetary gear device has come to be used as a speed reducer of a washing machine.

Japanese Examined Patent Publication No. 60-27320 (S.60.6.28) uses a planetary gear device as a speed reducer for a one-tank type spin washing machine. In this case, the outer shell internal gear of the planetary gear device is fixed to the casing by a plurality of screws that are long in the axial direction. Use 4 or 8 screws.

Since they are screwed, the outer shell internal gear and the casing are firmly integrated. However, the work of screwing is time consuming.

It is necessary to align the hole formed in the outer shell internal gear with the screw hole of the casing, insert the screw into the screw hole, and turn the screw with a screwdriver.

Another drawback is that the noise from the reducer is loud when rigidly coupled.

(A) Prior Art In USP4,503,719 and British Patent Publication GB2107425, four protrusions are provided on the outer periphery of the outer shell internal gear, four recesses are provided in the casing, and the protrusions are put in the recesses. The recess is wider, and the cushion material is inserted between the recess and the protrusion.

The outer shell internal gear is not rigidly connected to the casing. It can rotate slightly.

 However, the outer shell internal gear itself does not deform.

USP 2,801,552 (1957.8.6) is one in which an outer shell internal gear and a casing are connected by a link. This is also an example of soft coupling. However, since many links are used, the installation work would be rather complicated.

Australian Patent 205,245 (1956.8.30) has a large number of protrusions formed on the outer side of an outer shell internal gear, and a large number of recesses formed on the inner side of a casing, and the protrusions are fitted into the recesses. The outer shell internal gear is designed to be deformed. This is also a soft bond. However, the connection between the casing and the outer shell internal gear is extremely complicated. Installation is a difficult task and extremely difficult.

British Patent Publication GB2105815 (1983.3.20) proposes a torque limiter that rotates with respect to the casing when a strong torque is applied to the outer shell internal gear.

The present invention does not cause the outer shell internal gear to rotate with respect to the casing.

British Patent 1,116,791 (1968.6.12) forms many outer teeth on the outer circumference of an outer shell internal gear and many inner teeth on the inner circumference of a casing. The external teeth are inserted into the internal teeth, and a thin cushioning material is inserted between them. This is to reduce the impact force applied to the outer shell internal gear.

USP 3,776,067 (December 4, 1973) makes deep cuts in the sun gear and outer shell internal gear to allow these gears to deform. This is because the impact force is alleviated by the deformation.

In all of these, the casing and the outer shell internal gear are not connected rigidly but softly. It has the effect of weakening impact force and mitigating vibration and noise.

However, both are complicated mounting structures. Each part must be extremely accurate. The installation work is complicated and requires adjustment.

Japanese Patent Application No. 61-69674 (61.3.27 application) was created by the applicant. Several non-rotating arc pieces are formed at one end of the outer shell internal gear.

The same number of anti-rotation protrusions are formed on one end of the casing. The outer shell internal gear is moved in the axial direction so that the arc piece is inserted between the detent protrusions of the casing.

The rotation is stopped by the combination of both, but there is a gap between them in the rotational direction and the radial direction. Therefore, the outer shell internal gear can move with respect to the casing.

When the cover plate is attached to the casing, the planetary gear device is enclosed in the casing. Installation work for the casing is simplified. Do not screw the planetary gear unit itself to the casing.

Further, since the connection is loose, noise is reduced. There were such advantages. However, on the other hand, new difficulties appeared.

(C) Problem to be Solved by the Invention In the above invention, the outer shell internal gear is made of plastic. Therefore, it is possible to easily form a different shape such as a circular arc stop piece on the circumference.

Moreover, the toothed portion of the outer shell internal gear has a wide gap from the inner surface of the casing. This gap was 5-6 mm.

The wide gap is effective in blocking noise and cooling the gear with air.

Since it is thus far away from the casing, the plastic outer shell internal gear is easy to move in the radial direction.

Further, when the thickness of the portion where the teeth are provided is about 2 modules, the outer shell internal gear made of plastic becomes soft and easily bent in the radial direction. Since heat is generated with rotation, the outer shell internal gear becomes softer. Since the cylindrical portion is thin with 2 modules, the internal gear tends to bend outward when a strong torque is applied from the planetary gear. For this reason, the tooth portion sometimes flexes outward by two modules, and the tooth tip of the planetary gear may jump over the tooth tip of the outer shell internal gear by one tooth. This is shown in FIG.

When this happens, the meshing point of the planetary gear advances by one tooth. The meshing points of the other planetary gears do not change. Therefore, when there are two or more planetary gears, the meshing points do not match.

Depending on the module and the number of teeth, there are four planetary gears, and if the number of teeth on the planetary gears is 20 or less, if there is a mismatch as described above, the resistance to rotation suddenly increases, and almost no rotation is possible. Disappear.

If the motor is rotated infinitely, the load will be applied to the motor, and even if the motor is rotated, the tooth tip interference is strong and the tooth tips are rapidly worn.

 These difficulties are new.

If the outer shell internal gear is steel, zinc, aluminum, cast iron, or any other metal, no matter how thin the two modules will not bend outward.

The outer shell internal gear is plastic, and since it is thin, it flexes outward. The teeth mesh with each other in two modules. There is one module from the pitch circle to the tip of the tooth and 1.25 modules from the pitch circle to the tooth bottom, and the height of the overlapping portion is two modules.

For example, if the module is 0.7, 2 modules is 1.4 mm.

It is difficult to think that such a large amount of bending will occur, but in reality, the "jumping" of the tooth tip engagement occurs. As a result, the planetary gear set deteriorated rapidly.

The thickness excluding the teeth of the portion where the teeth of the outer shell internal gear are formed is simply referred to as the "base thickness". This was about 2 modules in the previous example.

If the base thickness is increased, the flexure is reduced, so that such a problem does not occur.

The one described as the conventional technique does not have such a problem because the base portion has a large thickness.

However, it is sometimes preferable that the base thickness t of the outer shell internal gear be thinner.

First of all, the material can be saved. If the outer shell internal gear is made of plastic, many raw materials are required in proportion to the base thickness t.

The other is that the larger the outer gear, the larger the casing, which is a disadvantage.

Furthermore, it may be better for the outer shell internal gear to be slightly bent. This is because a strong impact force can be relaxed by bending.

(D) Means for Solving the Problems In the present invention, the above problems are solved by imposing the following conditions on the relationship between the outer shell internal gear and the casing.

(1) The outer peripheral surface of the portion where the teeth of the outer shell internal gear are formed is flat.

(2) The thickness of the portion where the teeth are formed (base thickness t) is
1.5 to 3 modules.

(3) The inner peripheral surface of the casing, which corresponds to the outer peripheral surface of the portion where the teeth are formed (base portion), has a flat cylindrical shape and does not have a protrusion for preventing rotation.

(4) The distance g between the outer peripheral surface of the portion (base portion) where the teeth are formed and the inner peripheral surface of the casing is 0.5 to 2 modules in terms of the radius.

(5) The mechanism for preventing the outer shell internal gear from rotating with respect to the casing is formed at the end portion where the teeth are not provided.

(E) Action It has such characteristics. Of these, (4) is the most important. If the gap between the casing and the outer shell internal gear is two modules or more (in radius), it is possible that one tooth will fly at the meshing point. However, with 2 modules or less, such a thing cannot occur.

(1) and (3) correspond. If a protrusion for preventing rotation is provided outside the portion where the teeth are provided, the thickness of the base becomes uneven. Then, the pressure applied to the teeth and the bending of the teeth are not uniform. The pressure is not evenly distributed over the entire tooth width,
This means that only the tooth surface at one end is significantly worn.
Therefore, the thickness of the base portion (the portion with teeth) is made uniform.

The condition (2) is that the base of the outer shell internal gear is thin. It is an object of the present invention to prevent accidents caused by thinness. If it is thin, there is no such problem.

Depending on the plastic material and the operating temperature,
Two modules have this problem. Even with 3 modules, it can happen at high temperature. If the base is thinner than 1.5 modules, there is a risk of breakage, which is not desirable. Therefore, it is limited to 1.5 to 3 modules.

(5) corresponds to the conditions of (1) and (3), and it is necessary to form an anti-rotation mechanism somewhere, but these are to be the parts where teeth do not exist.

 The meaning of the condition (4) will be described with reference to FIG.

It is assumed that a strong torque is generated at the meshing point between the outer shell internal gear and the planetary gear. The outer shell internal gear is soft and bends outward. However, the gap g with the casing is 0.5 to 2 modules, which is smaller than 2 modules.

Since the tooth height is 2 modules, there is no chance that one tooth will slip.

The gap g should be smaller than 2 modules. But,
If it is too narrow, it will be difficult to insert the shell internal gear into the casing. With 1 module of diameter, you can insert it without hitting the casing wall. or,
Since it can move in the radial direction, it is possible to absorb errors in the shaft center.

(F) Example An example will be described with reference to the drawings.

FIG. 1 is a front view showing a state where the planetary gear device A is loaded into a casing B. Fig. 2 shows II- in Fig. 1.
It is II sectional drawing. FIG. 3 is a sectional view taken along the line III-III in FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG.

The detailed structure of the planetary gear device A is arbitrary. Here, what was invented by the applicant and has a tooth disc is illustrated.

Around the sun gear 1, four planet gears 2 (may be three) are provided, and these mesh with each other.

The planetary gear 2 meshes with the sun gear 1, but since the disks 6 and 7 having a diameter larger than the tip circle are provided on the left and right, the tip of the tooth cannot be seen from the outside.

Around the planetary gear 2, an outer shell internal gear 3 that meshes with these is provided. This also serves as a housing for the entire planetary gear unit A.

The carrier 4 comprises a main carrier disc 4a and a sub carrier disc 4b. Both planetary shafts 5 are supported at four points on the inner surface corresponding to the four corners of the square taken in the plane of the carrier 4.

 The planet gear 2 can freely rotate around the planet shaft 5.

In this example, the planetary gear 2 is composed of 3 members. The left and right equivalent planetary disks 6, 7 and the central planetary gear ring 8 sandwiched between them.

Planetary gear rings, for example, are made of plastic (eg Duracon). The planetary disks 6 and 7 can be made of sintered gold.

The planetary disks 6 and 7 have a large disk portion 23 larger than the addendum circle,
It is composed of a small disk portion 21 which is in contact with the rear surface of the planetary gear ring 8 and supports it.

The carrier 4 is fixed at four points forming an angle of 45 ° with the arrangement of the planetary shaft 5.

The main carrier board 4a has a convex portion 10 and an insertion protrusion 11 protruding above this.

The sub carrier board 4b is provided with a projection 12 and an insertion hole 13.

Insert the insertion protrusion 11 into the insertion hole 13 and crimp the tip. The caulking 28 secures the main and sub carrier boards 4a and 4b.

In this example, the main carrier board is made of die-cast aluminum and the sub carrier board is plastic. Besides, it can be made of zinc, steel plate, etc.

When the carrier is a steel plate (chromium molybdenum steel, etc.), the rivets are used to join the main and sub carrier plates.

In this example, the sun gear 1 is a sintered bond, the planetary gear ring 8
Is plastic. You can also use zinc and aluminum.

The outer shell internal gear 3 is made of plastic. Moreover, since it has a thin cylindrical shape, it is easily bent.

The outer shell internal gear 3 has a gear portion 25 on its inner surface and narrow cylindrical surfaces 26, 27 on both sides thereof. The cylindrical surfaces 26, 27 have a diameter larger than the root circle of the gear portion 25.

The gear portion 25 meshes with the planetary gear ring 8. Cylindrical surface 26,
The large disc portion 23 of the planetary discs 6 and 7 rolls on 27. Such a structure is disclosed in JP-A-58-94656.

The outer peripheral surface of the outer shell internal gear 3 is mostly a smooth cylindrical surface. It is called the smooth outer peripheral surface 18. At least the outer surface of the toothed gear portion 25 is smooth. The thickness of this portion (base portion) is 1.5 to 3 modules, which is thin.

Four non-rotating arc pieces 19 are formed at the end of the outer peripheral surface. This is not limited to four and may be two or three.

The outer shape of the whirl-stop arc piece 19 is determined by an arc-shaped outer rib 30, and an arc groove 31 and a circular hole 33 are formed.

These are for saving the material without impairing the strength of the arc piece 19. It doesn't matter if you don't.

The casing B can be made of materials such as aluminum, plastic, cast iron, and aluminum alloy.

The casing B is a cylindrical body 40 having a large diameter to accommodate the planetary gear device A, and a conical portion following the body 40 while reducing the diameter.
41 and a small-diameter cylindrical portion 42.

The cylindrical portion 42 has an output shaft hole 43 that opens an output shaft (not shown) to the outside.

Most of the inner surface of the body 40 is a smooth circumferential surface 44. A gap g between this and the smooth outer cylindrical surface 18 of the outer shell internal gear 3
Is 0.5 to 2 modules.

Four arcuate grooves 47 are formed on the outer end of the body 40. The remaining portion is a trapezoidal anti-rotation protrusion 45.

In the arc groove 47 of the casing B, the whirl-stop arc piece 19 of the outer shell internal gear 3 is fitted. Therefore, the anti-rotation protrusion 45 of the casing B has a shape complementary to the anti-rotation arc piece 19 of the outer shell internal gear 3.

These detent mechanisms are for detenting the outer shell internal gear with respect to the casing.

In the states shown in FIGS. 1 to 3, the planetary gear device is simply inserted into the casing. A cover plate 49 shown by a chain line in FIG. 3 is inserted into the end surface of the casing B, and a bolt (not shown) is screwed into the screw hole 48 of the casing to complete the mounting.

(G) Effects of the invention (1) Even in a planetary gear unit made of plastic and having a thin outer shell internal gear, the gap between the planetary gear unit and the casing is 2 modules or less. It won't happen.

(2) Since the outer shell internal gear is not directly fixed to the casing by the bolt, the mounting operation is extremely easy. No adjustment operation such as positioning is required.

(3) Since there is a gap between the outer shell internal gear and the casing, and the outer shell internal gear is made of thin plastic, it is easily bent and displaced. The effects of various errors are absorbed and the transmission efficiency is increased.

(4) Vibration is less likely to be transmitted to the casing due to the gap.
Effective in reducing noise.

[Brief description of drawings]

FIG. 1 is a front view showing a casing mounting structure of a planetary gear device of the present invention. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG. FIG. 5 shows that the outer shell internal gear has two modules for flexing teeth 1
Explanatory drawing which shows that the meshing point for one sheet flies. (A) The figure which bent outside. (B) is a figure which shows that a meshing point jumps. FIG. 6 is an explanatory view showing that the outer shell internal gear cannot bend by two modules because of the casing wall. 1 …… Sun gear 2 …… Planetary gear 3 …… Outer shell internal gear 4 …… Carrier 4a …… Main carrier board 4b …… Sub carrier board 5 …… Planetary shaft 6,7 …… Planetary disk 8 …… Planetary gear ring 10 …… Convex part 11 …… Insertion protrusion 12 …… Convex part 13 …… Insertion hole 14 …… Sun shaft hole 15 …… Carrier shaft hole 16 …… Planet shaft stop hole 17 …… Opening 18… … Smooth outer cylinder surface 19 …… Anti-rotating arc piece 21 …… Small disk part 23 …… Large disk part 25 …… Outer shell gear part 26,27 …… Cylindrical surface 28 …… Caulking 31 …… Arc groove 33 …… Circular hole 40 …… Body part 41 …… Cone part 42 …… Cylinder part 43 …… Output shaft hole 44 …… Inner peripheral surface 45 …… Rolling stop projection 47 …… Arc groove 48 …… Screw hole A… … Planetary gear unit B …… Casing

Claims (1)

(57) [Claims] 1. A sun gear 1, a suitable number of planet gears 2 around the sun gear 1 and meshing with the sun gear 1, and a tooth base around the sun gear 1 that meshes with the planet gears 2 has a thickness of 1.5 modules or less. A planetary gear set A comprising a two-module extremely thin plastic flexible outer shell internal gear 3 and a carrier 4 for supporting the planetary gear 2 by a planetary shaft 5.
Is attached to the casing B so that the tip of the tooth does not fly between the planet gears and the teeth of the outer shell internal gear, and the outer peripheral surface of the outer shell internal gear 3 at the portion where the teeth are present on the back surface. Is flat and has a non-rotating arc piece 19 formed on the outer circumference of the outer shell internal gear on the back surface where teeth do not exist, and the casing B
The outer shell internal gear 3 has a flat cylindrical portion in contact with the toothed portion, and a plurality of whirl-stop projections are formed on the cylindrical inner surface of the casing B in contact with the toothless portion of the outer shell internal gear 3. The portion 45 is formed, and the rotation preventing projection 45 of the casing B and the rotation preventing arc piece 19 of the outer shell internal gear 3 form the outer shell internal gear 3.
To the casing B, and the distance g between the flat surface of the outer shell internal gear 3 at the portion where the teeth are present on the back surface and the surface of the flat casing B is a radius of 0.5 module to 2
A casing mounting structure for a planetary gear unit, which is a module.