JPH0372851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field The present invention relates to a planetary gear device that has a wide range of uses as a speed reducer and a speed increaser.

(B) Prior art and its problems Since a planetary gear device has many meshing points between the sun gear and the planetary gear, and between the planetary gear and the outer shell internal gear, it is difficult to balance the forces at each meshing point at the same time. difficult. Even if machining accuracy is increased, good results are not necessarily obtained.

If the gears mesh too deeply into each other, noise and vibration will occur, and energy will be lost.

In order to prevent excessive meshing, some planetary gears have a pitch disc or pitch ring installed coaxially with the gear.

If a disk or ring with the same diameter as the pitch circle is attached to the side of the gear, radial force will be transmitted by the disk or ring. Therefore, even if there is eccentricity of the sun gear shaft or a positional error of the planetary shaft, the gears will not mesh excessively with each other.

For example, U.S. Patent No. 3,293,928 (December 27, 1966)
In the specification (published in Japan), in a torque converter in which an external gear and an internal gear mesh, a disk part and a ring part with a diameter equal to a pitch circle are integrally formed with each gear on both sides of both gears. The device is shown.

Further, US Pat. No. 3,548,673 (issued December 22, 1970) discloses a spur gear and a bevel gear in which a friction wheel having a diameter equal to a pitch circle is fixedly integrated on one side of the gear. It was difficult to set the backlash of the gears at the meshing point, so in order to eliminate the problem of backlash, the friction wheels transmitted radial force to each other.

These inventions broadly apply to gears in general, and are provided with a pitch disk or a pitch ring coaxially with the gear.

There are also inventions and ideas that apply such composite gears to planetary gears.

Utility Model Publication No. 30-16918 has rollers and cylindrical surfaces with outer diameters and inner diameters equal to the respective pitch circles on the side of the planetary gear and the side of the external shell internal gear that meshes with the planetary gear. .

The roller rolls on a cylindrical surface. Radial pressure is transmitted by the rollers, cylindrical surfaces. The gears only transmit rotational force to each other, and excessive meshing does not occur. It was an excellent idea.

However, in this invention, the planetary gears and rollers are provided spaced apart from each other on one long planetary shaft. The planetary shaft is longer, and the casing is also longer in the axial direction. The entire device becomes bulky and heavy. This increases manufacturing costs and
In some cases, it was difficult to use.

There are also ideas that attempt to overcome the inherent difficulties of planetary gears by using a completely different approach than using a disk or ring that is equal to the pitch circle.

The planetary gears are made of a highly elastic material, and meshing misalignment is absorbed by the elastic deformation of the planetary gears.

For example, the invention of Utility Model Publication No. 44-25692 can be mentioned. This is not a gear, but a planetary roller, and the planetary roller is made of an elastic material such as rubber.

However, if a gear is made of a flexible elastic body, the transmission torque will be suppressed to a low level due to slippage. Since it expands and contracts repeatedly and there is friction loss, it also has the disadvantage of generating heat and being easily fatigued. Since it does not mesh with gears, it can only be used for light loads.

Furthermore, a third solution was proposed.

For example, Utility Publication No. 35-17538, Special Publication No. 36-22661
This is the number.

This does not directly combine a planetary gear and a planetary shaft, but adds an intermediate ring between them. Intermediate ring and planetary gear (ring-shaped)
and can be mutually rotated. There is sufficient clearance between the intermediate ring and the planetary gear.

Due to the gap, the planetary gear ring can be displaced slightly relative to the axis in any direction. Therefore, the misalignment of the meshing points can be equalized. There is no need for pitch discs or pitch rings.

Such a gap-type planetary gear device may still be insufficient in terms of equal distribution of force at the meshing points. This method is effective if the carrier supporting the sun gear and planet gears can move radially to some extent. However, if the sun axis cannot move freely, this method will not be effective unless the gear itself has a large bump.

However, the present inventor believes that such an open gap type is the most effective for equalizing the meshing of a planetary gear.

(C) Three technical ideas As explained in detail in the previous section, in order to solve the problem of simultaneous misalignment of the meshing points of planetary gears, (1) Pitch disk, ring method (2) Elastic gear method (3) ) There were three different technical ideas for the gap method.

(1) looks very attractive. If the pitch disc is placed coaxially with the planet gear, the rotation speed of the disc and the planet gear will be the same, so there should be no slippage between the disc and the circumferential surface of the pitch ring, and they should roll correctly. be.

Among these, a planetary gear system was proposed that combined configurations (1) and (2). This is Special Publication No. 54-17111 (published on June 27, 1978).

The planetary gear has a thin ring shape so that it can be easily bent. A ring gear is sandwiched from both sides by pitch disks having concentric steps and an outer diameter equal to the pitch circle,
The planetary shaft is passed through the shaft holes of the two pitch discs.

In this invention, the gear is adapted to be locally bent at the root of the tooth. Planetary gears that are subjected to strong torque bend more strongly at their tooth bases, so the torque is alleviated. The idea is that this equalizes the transmitted torque for each planetary gear.

This invention, however, includes a planetary gear ring and
Since the gap between the discs is zero and both are fixed, the advantages of (3) cannot be combined.

Moreover, the inventor knows that the bending of the root of the tooth, which is said to be the greatest advantage of this invention, is actually almost impossible.

Suppose that three or four planetary gears have different transmission torques. A planetary gear ring subjected to a large torque will flex significantly at the root of the tooth. The deflection causes the phase of this planetary gear to lag, resulting in a slight reduction in torque. However, if the amount of deflection is different for each planetary gear, the transmitted torque will be different.

Then, the transmitted torque differs at the meshing point between the planetary gear and the sun gear. Therefore, the sun gear is subjected to non-uniform radial pressure. This will cause excessive meshing between the sun gear and the planet gear.

The present inventor has been involved in the research, development, manufacture, and sale of planetary gear devices for many years. The various planetary gear devices described above were actually manufactured and examined.

According to the experience of the present inventor, the gap method (3) is considered to be the most effective for equally distributing force in a planetary gear device.

Therefore, the present inventor invented a planetary gear device that combines (1) and (3) (Japanese Patent Application No. 114824/1982, Japanese Unexamined Patent Publication No. 17244/1983, published on February 1, 1987).

It has already been explained why the elastic gear system is ineffective. It is said that elastic deformation occurs unevenly and equalizes the meshing force, but elastic deformation is proportional to the applied force according to Hook's law. The fact that elastic deformation occurs unevenly means that the meshing forces are uneven.

If the meshing forces are uneven, there will be differences in the strength of the meshing, and this will not mean that the misalignment has been alleviated.

Rather, it is preferable to provide sufficient backlash so that the transmitted torque is always the same.

Furthermore, the present inventor also has doubts about the pitch disk and pitch ring method (1).

If the pitch ring and disk were perfectly circular, the disk and ring would be in constant contact. However, pitch rings cannot be perfectly circular. This is because there are processing errors. Therefore, the inner diameter of the pitch ring should be slightly larger than the pitch circle,
The outer diameter of the pitch disk is made slightly smaller than the pitch circle. In this way, in processing, Pitzchi disk,
Provide a tolerance so that the ring does not come into close contact with the ring and leaves a gap.

In this case, the pitch ring on the outer shell internally geared vehicle side and the pitch disks on both sides of the planetary gear do not always come into contact with each other. In fact, there is a lot of time spent without contact.

If they are in contact, there is some kind of dimensional error and the pitch ring is not a perfect circle but close to an ellipse.
This happens when a planetary gear is located on the short side of the circle, or when the centrifugal force is so strong that the pitch disc is pressed against the pitch ring.

Also, if the planetary gear set is set vertically rather than horizontally and there is play between the sun gear and its shaft, the weight of the carrier will cause the pitch disc of the planetary gear at the lowest point to touch the pitch ring. There may be contact.

However, normally the pitch disc and pitch ring are often separated.

Therefore, the inventor of the present invention proposed that in the pitch circle, a disk,
Isn't there little need for the rings to be in contact?
I thought.

Rather, I came up with the idea that it would be better to have the disc and ring in contact at the tips and bottoms of the teeth.

With the pitch disc and pitch ring, the outer shell internal gear and the planetary gear will not come off in the lateral direction, so the entire planetary gear system will become one cohesive unit. This is different from conventional planetary gears. Because the tip of the tooth (1 module) hangs over the opposing disc or ring, it cannot be pulled out laterally.

However, since it is a single module at the tip of the tooth, it is prone to wear due to contact with the disc and ring. Another drawback is that thrust force cannot be transmitted sufficiently.

Therefore, the present inventor invented a planetary gear device in which the outer diameter of the disks on both sides of the planetary gear is larger than the tip circle, and the inner diameter of the cylindrical surfaces on both sides of the outer shell internal gear is larger than the root circle ( Patent application 1983-193113, 1983-
94656, published 58.6.4).

This device had the advantage of reducing the number of parts because the outer shell internal gear was made of one piece.

(d) Structure of the present invention The present inventor further decided to pursue the gap method (3) among the measures (1) to (3) described in the previous section using the disk and ring methods. This time, conversely, assume that the outer diameter of the disk of the planetary gear is equal to or less than the root circle, and the inner diameter of the cylindrical surface portion of the outer shell internal gear is smaller than the tip circle.

Furthermore, the disc and ring are not provided on both sides of the gear, but only on one side.

As for the outer shell internal gear, it has a gear part and a cylindrical part on one side of which has an inner diameter smaller than the addendum circle of the outer shell internal gear.

The planetary gear consists of a ring-shaped planetary gear ring and a planetary sleeve. This is a separate member.

The planetary sleeve is a member having a cylindrical part loosely fitted between the planetary gear ring and the planetary shaft, and a disc part on one side of the cylindrical part and having an outer diameter smaller than the bottom circle of the planetary gear.

Ultimately, the planetary gear system of the present invention has (1) an appropriate number of planetary gears that mesh with the sun gear, (2) an outer shell internal gear that meshes with these, and (3) the planetary gears connected to the planetary shaft. A planetary gear device comprising: (4) a ring-shaped planetary gear ring; and (5) a planetary gear loosely fitted between the planetary gear ring and the planetary shaft. (6) An external shell internal gear consists of a cylindrical part and a planetary sleeve integrally formed with a disc part with an outer diameter smaller than the tooth root circle of the planetary gear on one side of the cylindrical part. The planetary sleeve has a cylindrical surface portion which faces and contacts the disk portion of the planetary sleeve and has an inner diameter equal to or smaller than the tip circle of the outer shell internal gear.

(e) Examples An explanation will be given with reference to drawings showing examples.

FIG. 1 is a partially cutaway front view of a planetary gear device according to an embodiment of the present invention. FIG. 2 is a partially cutaway rear view, and FIG. 3 is a cross-sectional view taken in FIG. 1.

Although the planetary gear train has a sun gear in the center, the device of the invention allows the sun gear to be inserted later. Even without the sun gear, it is still a cohesive unit.

This is the aforementioned Tokukai No. 54-17111 and Tokukai No. 58
-17244, JP-A No. 58-94656).

In these planetary gear devices, the space into which the sun gear should be inserted is slightly blocked by the disk on the planetary gear side, making it impossible to insert the sun gear after the unit is assembled.

However, in the present invention, since the outer diameter of the disk portion on the side of the planetary gear is smaller than the diameter of the root circle, the sun gear can be inserted later.

For this reason, the state before the sun gear is inserted is shown here. The sun gear does not appear in the diagram.

In reality, it is convenient to cut a gear on the output shaft of the motor and use it as the sun gear instead of using the sun gear. This is because the number of members can be reduced by the number of sun gears.

The planetary gear device 1 of the present invention has an appropriate number (four in this example) of planetary gears 2 that mesh with a central sun gear.
, an outer shell internal gear 3 that surrounds and meshes with the planetary gear 2, and a carrier 4 that supports the planetary gear 2 in a rotationally symmetrical position.

The planetary shaft 5 rotatably supports the planetary gear 2 with respect to the carrier 4.

The planetary gear 2 is a loose combination of a planetary gear ring 7, which is a ring-shaped gear cut on the outer periphery, and a planetary sleeve 6.

The carrier 4 is a combination of a carrier plate 4a and a carrier sub-plate 4b.

A convex portion 10 and an insertion protrusion 11 are formed on the inner surface of the main carrier disk 4a at rotationally symmetrical positions.

At a corresponding position on the inner surface of the sub-carrier plate 4b,
A protrusion 12 and an insertion hole 13 are provided therein.

The insertion protrusion 11 of the main carrier disc 4a is inserted into the insertion hole 13 of the auxiliary carrier disc 4b to combine both carrier discs 4a and 4b.

This may be further bonded with an adhesive.

Alternatively, the insertion protrusion 11 may be made to protrude outside the convex portion 12 and ultrasonic welding may be performed.

This example shows that both carrier disks 4a, 4b are made of plastic.

Of course, the carrier plate can also be made of metal. In this case, both carrier plates are welded together through a connecting rod or caulked and fixed with rivets.

The center of the main carrier disk 4a is a central raised portion 14 that is raised outwardly. A carrier shaft hole 15 is provided at this center. This has splines or serrations cut into it. An output shaft (if used as a speed reducer) is installed in the carrier shaft hole 15.

The carrier discs 4a, 4b have the protrusions 10, 1.
There are planetary shaft fixing holes 16, 16 in the middle position of 2,
Both ends of the planetary shaft 5 are inserted and fixed here.

There is an opening 17 in the center of the sub-carrier disk 4b,
From here, a sun gear or a motor shaft with a sun gear cut off at the tip can be inserted.

The pitch circle 18 of the planetary gear 2 is shown by a chain line.
The root circle 19 is smaller than this. In FIGS. 3 and 4, the boundary with the hatched area indicating the cross section of the gear is the root circle. This is 1 to 1.25 modules (radius) smaller than the Pituchi circle.

Since the sun gear can be inserted through the opening 17, the planetary gear 2 is inserted at the end of the opening 17 in FIG.
Part of the bottom of the tooth is visible.

FIG. 4 is an enlarged sectional view of only the vicinity of the planetary gear 2.

The two members constituting the planetary gear 2 are a planetary sleeve 6 and a planetary gear ring 7 loosely fitted on the outside of the planetary sleeve.

There is a gap between the planetary sleeve 6 and the planetary gear ring 7. This is the reason why we adopted the above-mentioned (3) gap method.

The planetary sleeve 6 includes a cylindrical portion 20 interposed between the planetary shaft 5 and the planetary gear ring 7, and a disk portion 21 on one side of the cylindrical portion 20 having an outer diameter D smaller than the root diameter _P2 of the planetary gear. It becomes more. The cylindrical part 20 and the disc part 21 are made integrally.

Corresponding to the structure of the planetary gear 2, the outer shell internal gear 3
It also consists of a gear part 22 and a cylindrical surface part 23.

The gear portion 22 meshes with the planetary ring 7.

The cylindrical surface portion 23 is the disk portion 21 of the planetary sleeve 6.
Opposite contact with. The inner diameter R of the cylindrical surface portion 23 is smaller than the diameter I ₁ of the addendum circle of the external internal gear.

The planetary sleeve 6 has a shaft through hole 24 in the center, through which the planetary shaft 5 passes.

The outer shell internal gear 3 has several bolt holes 25 through which bolts are passed to fix the planetary gear set to a casing (not shown).

(F) Effects (1) Since the planetary gear 2 is divided into the planetary sleeve 6 and the planetary gear ring 7, and they are combined so that a gap exists in the radial direction, misalignment of meshing occurs between the planetary gears. Never.

(2) Since the planetary gear 2 and the outer shell internal gear 3 are provided with the disc portion 21 and the cylindrical surface portion 23 that are in opposing contact with each other, the gears do not mesh strongly with each other.

(3) Since the outer diameter D of the disk portion 21 of the planetary sleeve is smaller than or equal to the diameter _P2 of the bottom circle of the planetary gear, D≦ _P2.The sun gear can be inserted later.

Therefore, if the teeth are cut directly on the tip of the motor shaft, one sun gear can be omitted.

(4) Since the disk portion 21 and the cylindrical surface portion 23 are provided on one side rather than on both sides, in the case of plastic, the planetary gear 3 can be made as one piece by injection molding.

Moreover, the planetary gear can also be made of two members.

The number of parts is reduced, and the number of assembly steps is also reduced.

In a structure with pitch discs and pitch rings on both sides, three members were required for the planetary gear and three members for the outer shell internal gear.

When made of metal, it is difficult to integrate the outer shell internal gear 3, but it can still be done by combining two members.

(G) Discussion In the present invention, the disc portion 21 of the planetary gear 2 and the cylindrical surface portion 23 of the outer shell internal gear 3 do not contact each other with pitch circles.

If the pitch circles are in contact with each other, there is no difference in circumferential speed.
If contact occurs at a location outside the pitch circle, there should be a difference in circumferential speed.

If there is a difference in circumferential speed, the disc part 21 will be different from the cylindrical surface part 2.
I ended up skidding on top of 3. Therefore, there may be a fear that heat and noise will be generated.

The diameters of the pitch circle, tooth tip circle, and tooth root circle of the planetary gear.
Let them be P ₀ , P ₁ , and P ₂ . Pitch circle of external internal gear,
Let the diameters of the tip circle and root circle be I ₀ , I ₁ , and I ₂ . The outer diameter of the planetary disk portion is D, and the inner diameter of the cylindrical surface portion of the outer shell internal gear is R.

(1) What the present inventor calls a Pitch disk or Pitch ring type is one in which D=P ₀ R=I ₀ .

(2) The thrust disk type that was previously invented by the present inventor (Japanese Patent Laid-Open No. 58-94656) satisfies D≧P ₁ R≧I ₂ .

(3) In contrast, the present invention sets D≦P ₂ R≦I ₁ .

Pitch circles for sun gears, planetary gears, and outer shell internal gears
S ₀ , P ₀ , and I ₀ are the modules multiplied by the numbers of teeth Z _s , Z _p , and Z _i .

In a system where the carrier is fixed, let the rotational angular velocities of each be Ω′ _s , Ω′ _p , and Ω′ _i . This amount includes the direction of rotation.

Since the peripheral speeds at the meshing point are equal, −Z _s Ω′ _s = +Z _p Ω′ _p =Z _i Ω′ _i (1). Also, since it constitutes a planetary gear system, Z _i =Z _s +2Z _p (2).

If the angular velocity of the carrier is Ω _c and the rotational angular velocity of each gear is Ω _s , Ω _p , and Ω _i in a system (laboratory system) in which the external internal gear is fixed, then Ω _s = Ω′ _s − Ω′ _i (3) Ω _p =Ω′ _p −Ω _i (4) Ω _c =0−Ω′ _i (5) Ω _i =Ω′ _i −Ω′ _i =0 (6) The reduction ratio r is usually defined as r=Ω _c /Ω _s (7). This is the carrier rotation speed relative to the sun gear rotation speed.

From these equations, we obtain Z _s Ω _s = (Z _i +Z _s )Ω _c (8). The reduction ratio r can be written as r=Z _s /Z _i +Z _s (9) or r=Z _s /2(Z _s +Z _p ) (10).

The difference Δ in the circumferential speed between the disk portion (diameter D) and the cylindrical surface portion (inner diameter R) is given by Δ=DΩ′ _p −RΩ′ _i (11). From equations (1), (3), (5), and (7), Δ=S ₀ (1−r) (R/I ₀ −D/P ₀ )Ω _s (12).

The difference between R and I ₀ and the difference between D and P ₀ may be about 1 module or more, but these differences should be equal. In order for the disc part and the cylindrical surface part to make contact, they must be equal (dimensional tolerances are not considered in this discussion). Therefore, let this difference be δ.

I ₀ −R=δ (13) P ₀ −D=δ (14). δ is positive.

Substituting this, the circumferential speed difference Δ can be written as Δ=δrΩ _s /1−2r (15). This is an expression based on the rotational angular velocity of the sun gear Ω _s (input rotation speed), but it can also be written as Δ=δΩ _c /1−2r (16) in relation to the carrier rotation (output rotation) speed.

The simplest expression would be to write Δ=-δΩ _p (17) for the rotational angular velocity Ω _p of the planetary gear.

Since δ is about 1 module to 1.5 modules, it is only an extremely small difference in circumferential speed.

Since the cylindrical surface of the outer shell internal gear becomes smaller by δ and the disc part of the planetary gear becomes smaller by δ, it may seem at first glance that there is a circumferential speed difference of 2δΩ _p , but this is not the case. It is half of that, δΩ _p .

Moreover, in reality, the outer diameter of the disc part has a negative tolerance, and the inner diameter of the cylindrical part has a positive tolerance, and clearance is provided in between. Therefore, the contact time between the disk and the cylinder is short and the contact pressure is also low.
Furthermore, since the circumferential speed difference Δ is small, there is almost no heat generation.

[Brief explanation of drawings]

FIG. 1 is a partially broken front view of a planetary gear device according to an embodiment of the present invention. Figure 2 is a partially cutaway rear view of the same item. FIG. 3 is a sectional view taken in FIG. 1. FIG. 4 is an enlarged sectional view of only the vicinity of the planetary gear in FIG. 3. 1... Planetary gear device, 2... Planetary gear, 3...
...Outer shell internal gear, 4...Carrier, 4a...Main carrier disk, 4b...Sub-carrier disk, 5...Planet shaft, 6...Planetary sleeve, 7...Planetary gear ring, 10...Protrusion , 11... insertion protrusion, 12...
Convex portion, 13...Insertion hole, 14...Central raised portion, 1
5...Carrier shaft hole, 16...Planet shaft fixing hole, 1
7...Opening, 18...Pitch circle, 19...Tooth bottom circle, 20...Cylindrical part, 21...Disc part, 22...
Gear part, 23...Cylindrical surface part, 24...Shaft through hole,
25...Bolt through hole.

Claims (1)

[Claims] 1 Appropriate number of planetary gears that should mesh with the sun gear 2
In a planetary gear device comprising an outer shell internal gear 3 that meshes with the outer shell internal gear 3, and a carrier 4 which supports the planetary gear 2 by a planetary shaft 5 and is rotatably provided,
The planetary gear 2 includes a ring-shaped planetary gear ring 7,
One planetary sleeve integrally formed with a cylindrical part 20 loosely fitted between the planetary gear ring 7 and the planetary shaft 5, and a disc part 21 having an outer diameter smaller than the tooth root circle of the planetary gear on one side of the cylindrical part 20. 6, the outer shell internal gear 3 has a gear portion 22 and one side thereof in opposing contact with the disc portion 21 of the planetary sleeve 6, and has an inner diameter that is equal to or smaller than the addendum circle of the outer shell internal gear. A planetary gear device comprising a cylindrical surface portion 23.